NSRegularExpression
An immutable representation of a compiled regular expression that you apply to Unicode strings.?
Declaration
```
class NSRegularExpression:NSObject
```
Discussion
The fundamental matching method for?NSRegularExpression?is a Block iterator method that allows clients to supply a Block object which will be invoked each time the regular expression matches a portion of the target string. There are additional convenience methods for returning all the matches as an array, the total number of matches, the first match, and the range of the first match.
An individual match is represented by an instance of the?NSTextCheckingResult?class, which carries information about the overall matched range (via its?range?property), and the range of each individual capture group (via the?range(at:)?method). For basic?NSRegularExpression?objects, these match results will be of type?regularExpression, but subclasses may use other types.
The ICU regular expressions supported by?NSRegularExpression?are described at?http://userguide.icu-project.org/strings/regexp.
Examples Using NSRegularExpression
What follows are a set of graduated examples for using the?NSRegularExpression?class. All these examples use the regular expression?\\b(a|b)(c|d)\\b?as their regular expression.
This snippet creates a regular expression to match two-letter words, in which the first letter is “a” or “b” and the second letter is “c” or “d”. Specifying?caseInsensitive?means that matches will be case-insensitive, so this will match “BC”, “aD”, and so forth, as well as their lower-case equivalents.
NSError *error =NULL;NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"\\b(a|b)(c|d)\\b"options:NSRegularExpressionCaseInsensitive? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? error:&error];
The?numberOfMatches(in:options:range:)?method provides a simple mechanism for counting the number of matches in a given range of a string.
NSUInteger numberOfMatches = [regex numberOfMatchesInString:string? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? options:0range:NSMakeRange(0, [string length])];
If you are interested only in the overall range of the first match, the?rangeOfFirstMatch(in:options:range:)?method provides it for you. Some regular expressions (though not the example pattern) can successfully match a zero-length range, so the comparison of the resulting range with?{NSNotFound, 0}?is the most reliable way to determine whether there was a match or not.
The example regular expression contains two capture groups, corresponding to the two sets of parentheses, one for the first letter, and one for the second. If you are interested in more than just the overall matched range, you want to obtain an?NSTextCheckingResult?object corresponding to a given match. This object provides information about the overall matched range, via its?range?property, and also supplies the capture group ranges, via the?range(at:)method. The first capture group range is given by?[result rangeAtIndex:1], the second by?[result rangeAtIndex:2]. Sending a result the??range(at:)?message and passing?0?is equivalent to?[result range].
If the result returned is non-nil, then?[result range]?will always be a valid range, so it is not necessary to compare it against?{NSNotFound, 0}. However, for some regular expressions (though not the example pattern) some capture groups may or may not participate in a given match. If a given capture group does not participate in a given match, then?[result rangeAtIndex:idx]?will return?{NSNotFound, 0}.
NSRange rangeOfFirstMatch = [regex rangeOfFirstMatchInString:string options:0range:NSMakeRange(0, [string length])];if(!NSEqualRanges(rangeOfFirstMatch,NSMakeRange(NSNotFound,0))) {? ? NSString *substringForFirstMatch = [string substringWithRange:rangeOfFirstMatch];}
The?matches(in:options:range:)?returns all the matching results.
NSArray *matches = [regex matchesInString:string? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? options:0range:NSMakeRange(0, [string length])];for(NSTextCheckingResult *matchinmatches) {? ? NSRange matchRange = [match range];? ? NSRange firstHalfRange = [match rangeAtIndex:1];? ? NSRange secondHalfRange = [match rangeAtIndex:2];}
The?firstMatch(in:options:range:)?method is similar to?matches(in:options:range:)?but it returns only the first match.
NSTextCheckingResult *match = [regex firstMatchInString:string? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? options:0range:NSMakeRange(0, [string length])];if(match) {? ? NSRange matchRange = [match range];? ? NSRange firstHalfRange = [match rangeAtIndex:1];? ? NSRange secondHalfRange = [match rangeAtIndex:2]; }
The Block enumeration method?enumerateMatches(in:options:range:using:)?is the most general and flexible of the matching methods of?NSRegularExpression. It allows you to iterate through matches in a string, performing arbitrary actions on each as specified by the code in the Block and to stop partway through if desired. In the following example case, the iteration is stopped after a certain number of matches have been found.?
If neither of the special options?reportProgress?or?reportCompletion?is specified, then the result argument to the Block is guaranteed to be non-nil, and as mentioned before, it is guaranteed to have a valid overall range. See?NSRegularExpression.MatchingOptions?for the significance of?reportProgress?or?reportCompletion.
__block NSUInteger count =0;[regex enumerateMatchesInString:string options:0range:NSMakeRange(0, [string length]) usingBlock:^(NSTextCheckingResult *match, NSMatchingFlags flags, BOOL *stop){? ? NSRange matchRange = [match range];? ? NSRange firstHalfRange = [match rangeAtIndex:1];? ? NSRange secondHalfRange = [match rangeAtIndex:2];if(++count >=100) *stop = YES;}];
NSRegularExpression?also provides simple methods for performing find-and-replace operations on a string. The following example returns a modified copy, but there is a corresponding method for modifying a mutable string in place. The template specifies what is to be used to replace each match, with?$0?representing the contents of the overall matched range,?$1?representing the contents of the first capture group, and so on. In this case, the template reverses the two letters of the word.
NSString *modifiedString = [regex stringByReplacingMatchesInString:string? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? options:0range:NSMakeRange(0, [string length])? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? withTemplate:@"$2$1"];
Concurrency and Thread Safety
NSRegularExpression?is designed to be immutable and thread safe, so that a single instance can be used in matching operations on multiple threads at once. However, the string on which it is operating should not be mutated during the course of a matching operation, whether from another thread or from within the Block used in the iteration.
Regular Expression Syntax
The following tables describe the character expressions used by the regular expression to match patterns within a string, the pattern operators that specify how many times a pattern is matched and additional matching restrictions, and the last table specifies flags that can be included in the regular expression pattern that specify search behavior over multiple lines (these flags can also be specified using the?NSRegularExpression.Options?option flags.
Regular Expression Metacharacters
Table 1?describe the character sequences used to match characters within a string.
Table 1
Regular Expression Metacharacters
Character ExpressionDescription
\aMatch a BELL,?\u0007
\AMatch at the beginning of the input. Differs from?^?in that?\A?will not match after a new line within the input.
\b, outside of a [Set]Match if the current position is a word boundary. Boundaries occur at the transitions between word (\w) and non-word (\W) characters, with combining marks ignored. For better word boundaries, see?useUnicodeWordBoundaries.
\b, within a [Set]Match a BACKSPACE,?\u0008.
\BMatch if the current position is not a word boundary.
\cXMatch a?control-X?character
\dMatch any character with the Unicode General Category of Nd (Number, Decimal Digit.)
\DMatch any character that is not a decimal digit.
\eMatch an?ESCAPE,?\u001B.
\ETerminates a?\Q ... \E?quoted sequence.
\fMatch a FORM FEED,?\u000C.
\GMatch if the current position is at the end of the previous match.
\nMatch a?LINE FEED,?\u000A.
\N{UNICODE CHARACTER NAME}Match the named character.
\p{UNICODE PROPERTY NAME}Match any character with the specified Unicode Property.
\P{UNICODE PROPERTY NAME}Match any character not having the specified Unicode Property.
\QQuotes all following characters until?\E.
\rMatch a CARRIAGE RETURN, \u000D.
\sMatch a white space character. White space is defined as [\t\n\f\r\p{Z}].
\SMatch a non-white space character.
\tMatch a HORIZONTAL TABULATION,?\u0009.
\uhhhhMatch the character with the hex value?hhhh.
\UhhhhhhhhMatch the character with the hex value?hhhhhhhh. Exactly eight hex digits must be provided, even though the largest Unicode code point is?\U0010ffff.
\wMatch a word character. Word characters are [\p{Ll}\p{Lu}\p{Lt}\p{Lo}\p{Nd}].
\WMatch a non-word character.
\x{hhhh}Match the character with hex value?hhhh. From one to six hex digits may be supplied.
\xhhMatch the character with two digit hex value?hh.
\XMatch a Grapheme Cluster.
\ZMatch if the current position is at the end of input, but before the final line terminator, if one exists.
\zMatch if the current position is at the end of input.
\nBack Reference. Match whatever the?nth capturing group matched.?n?must be a number?≥ 1?and?≤?total number of capture groups in the pattern.
\0oooMatch an Octal character.??ooo?is from one to three octal digits.??0377?is the largest allowed Octal character. The leading zero is required; it distinguishes Octal constants from back references.
[pattern]Match any one character from the pattern.
.Match any character. See?dotMatchesLineSeparators?and the?scharacter expression in?Table 4.
^Match at the beginning of a line. See?anchorsMatchLines?and the?\mcharacter expression in?Table 4.
$Match at the end of a line. See?anchorsMatchLines?and the?m?character expression in?Table 4.
\Quotes the following character. Characters that must be quoted to be treated as literals are?* ? + [ ( ) { } ^ $ | \ . /
Regular Expression Operators
Table 2?defines the regular expression operators.
Table 2
Regular Expression Operators
OperatorDescription
|Alternation.?A|B?matches either?A?or?B.
*Match?0?or more times. Match as many times as possible.
+Match?1?or more times. Match as many times as possible.
?Match zero or one times. Prefer one.
{n}Match exactly?n?times.
{n,}Match at least?n?times. Match as many times as possible.
{n,m}Match between?n?and?m?times. Match as many times as possible, but not more than?m.
*?Match?0?or more times. Match as few times as possible.
+?Match 1 or more times. Match as few times as possible.
??Match zero or one times. Prefer zero.
{n}?Match exactly n times.
{n,}?Match at least n times, but no more than required for an overall pattern match.
{n,m}?Match between n and m times. Match as few times as possible, but not less than n.
*+Match 0 or more times. Match as many times as possible when first encountered, do not retry with fewer even if overall match fails (Possessive Match).
++Match 1 or more times. Possessive match.
?+Match zero or one times. Possessive match.
{n}+Match exactly?n?times.
{n,}+Match at least?n?times. Possessive Match.
{n,m}+Match between?n?and?m?times. Possessive Match.
(...)Capturing parentheses. Range of input that matched the parenthesized subexpression is available after the match.
(?:...)Non-capturing parentheses. Groups the included pattern, but does not provide capturing of matching text. Somewhat more efficient than capturing parentheses.
(?>...)Atomic-match parentheses. First match of the parenthesized subexpression is the only one tried; if it does not lead to an overall pattern match, back up the search for a match to a position before the "(?>"
(?# ... )Free-format comment?(?# comment ).
(?= ... )Look-ahead assertion. True if the parenthesized pattern matches at the current input position, but does not advance the input position.
(?! ... )Negative look-ahead assertion. True if the parenthesized pattern does not match at the current input position. Does not advance the input position.
(?<= ... )Look-behind assertion. True if the parenthesized pattern matches text preceding the current input position, with the last character of the match being the input character just before the current position. Does not alter the input position. The length of possible strings matched by the look-behind pattern must not be unbounded (no * or + operators.)
(?<! ... )Negative Look-behind assertion. True if the parenthesized pattern does not match text preceding the current input position, with the last character of the match being the input character just before the current position. Does not alter the input position. The length of possible strings matched by the look-behind pattern must not be unbounded (no * or + operators.)
(?ismwx-ismwx:...?)Flag settings. Evaluate the parenthesized expression with the specified flags enabled or -disabled. The flags are defined in?Flag Options.
(?ismwx-ismwx)Flag settings. Change the flag settings. Changes apply to the portion of the pattern following the setting. For example, (?i) changes to a case insensitive match.The flags are defined in?Flag Options.
Template Matching Format
The?NSRegularExpression?class provides find-and-replace methods for both immutable and mutable strings using the technique of template matching.?Table 3?describes the syntax.
Table 3
Template Matching Format
CharacterDescriptions
$nThe text of capture group n will be substituted for $n.?n?must be?>= 0?and not greater than the number of capture groups. A?$?not followed by a digit has no special meaning, and will appear in the substitution text as itself, a?$.
\Treat the following character as a literal, suppressing any special meaning. Backslash escaping in substitution text is only required for '$' and '\', but may be used on any other character without bad effects.
The replacement string is treated as a template, with?$0?being replaced by the contents of the matched range,?$1?by the contents of the first capture group, and so on. Additional digits beyond the maximum required to represent the number of capture groups will be treated as ordinary characters, as will a?$?not followed by digits. Backslash will escape both?$?and?\.
Flag Options
The following flags control various aspects of regular expression matching. These flag values may be specified within the pattern using the?(?ismx-ismx)?pattern options. Equivalent behaviors can be specified for the entire pattern when an?NSRegularExpression?is initialized, using the?NSRegularExpression.Options?option flags.
Table 4
Flag Options
Flag (Pattern)Description
iIf set, matching will take place in a case-insensitive manner.
xIf set, allow use of white space and #comments within patterns
sIf set, a "." in a pattern will match a line terminator in the input text. By default, it will not. Note that a?carriage-return / line-feed pair?in text behave as a single line terminator, and will match a single "." in a regular expression pattern
mControl the behavior of "^" and "$" in a pattern. By default these will only match at the start and end, respectively, of the input text. If this flag is set, "^" and "$" will also match at the start and end of each line within the input text.
wControls the behavior of?\b?in a pattern. If set, word boundaries are found according to the definitions of word found in Unicode UAX 29, Text Boundaries. By default, word boundaries are identified by means of a simple classification of characters as either “word” or “non-word”, which approximates traditional regular expression behavior. The results obtained with the two options can be quite different in runs of spaces and other non-word characters.
Performance
NSRegularExpression?implements a nondeterministic finite automaton matching engine. As such, complex regular expression patterns containing multiple?*?or?+?operators may result in poor performance when attempting to perform matches — particularly failing to match a given input. For more information, see the?“Performance Tips” section of the ICU User Guide.
ICU License
Table 1,?Table 2,?Table 3,?Table 4?are reproduced from the ICU User Guide, Copyright (c) 2000 - 2009 IBM and Others, which are licensed under the following terms:
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Topics
Creating Regular Expressions
init(pattern: String,?options: NSRegularExpression.Options)
Returns an initialized NSRegularExpression instance with the specified regular expression pattern and options.
Declaration
init(pattern:String,options:NSRegularExpression.Options= [])throws
Parameters
pattern
The regular expression pattern to compile.
options
The regular expression options that are applied to the expression during matching. See?NSRegularExpression.Options?for possible values.
error
An out value that returns any error encountered during initialization. Returns an?NSError?object if the regular expression pattern is invalid; otherwise returns?nil.firstMatchInString:options:range
Return Value
An instance of?NSRegularExpression?for the specified regular expression and options.
Discussion
Handling Errors In Swift:
In Swift, this API is imported as an initializer and is marked with the?throws?keyword to indicate that it throws an error in cases of failure.
You call this method in a?try?expression and handle any errors in the?catch?clauses of a?do?statement, as described in?Error Handling?in?The Swift Programming Language?and?About Imported Cocoa Error Parameters.
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
regularExpressionWithPattern:options:error:
Getting the Regular Expression and Options
Returns the regular expression pattern.
Declaration
varpattern:String{get}
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
regularExpressionWithPattern:options:error:
var?options: NSRegularExpression.Options
Returns the options used when the regular expression option was created.
Declaration
varoptions:NSRegularExpression.Options{get}
Discussion
The options property specifies aspects of the regular expression matching that are always used when matching the regular expression. For example, if the expression is case sensitive, allows comments, ignores metacharacters, etc. See?NSRegularExpression.Options?for a complete discussion of the possible constants and their meanings.
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
regularExpressionWithPattern:options:error:
var?numberOfCaptureGroups: Int
Returns the number of capture groups in the regular expression.
Declaration
varnumberOfCaptureGroups:Int{get}
Discussion
A capture group consists of each possible match within a regular expression. Each capture group can then be used in a replacement template to insert that value into a replacement string.
This value puts a limit on the values of?n?for?$n?in templates, and it determines the number of ranges in the returned?NSTextCheckingResult?instances returned in the?match...?methods.?
An exception will be generated if you attempt to access a result with an index value exceeding?numberOfCaptureGroups-1.
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
Searching Strings Using Regular Expressions
Returns the number of matches of the regular expression within the specified range of the string.
Declaration
funcnumberOfMatches(instring:String,options:NSRegularExpression.MatchingOptions= [],range:NSRange) ->Int
Parameters
string
The string to search.
options
The matching options to use. See?NSRegularExpression.MatchingOptions?for possible values.
range
The range of the string to search.
Return Value
The number of matches of the regular expression.
Discussion
This is a convenience method that calls?enumerateMatches(in:options:range:using:).
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
rangeOfFirstMatch(in:options:range:)
enumerateMatches(in:options:range:using:)
Enumerates the string allowing the Block to handle each regular expression match.
Declaration
funcenumerateMatches(instring:String,options:NSRegularExpression.MatchingOptions= [],range:NSRange,usingblock: (NSTextCheckingResult?,NSRegularExpression.MatchingFlags,UnsafeMutablePointer<ObjCBool>) ->Void)
Parameters
string
The string.
options
The matching options to report. See?NSRegularExpression.MatchingOptions?for the supported values.
range
The range of the string to test.
block
The Block enumerates the matches of the regular expression in the string.
The block takes three arguments:
result
An?NSTextCheckingResult?specifying the match. This result gives the overall matched range via its?range?property, and the range of each individual capture group via its?range(at:)?method. The range {NSNotFound, 0} is returned if one of the capture groups did not participate in this particular match.
flags
The current state of the matching progress. See?NSRegularExpression.MatchingFlags?for the possible values.
stop
A reference to a Boolean value. The Block can set the value to?true?to stop further processing of the array. The stop argument is an out-only argument. You should only ever set this Boolean to?true?within the Block.
The Block returns void.
Discussion
This method is the fundamental matching method for regular expressions and is suitable for overriding by subclassers. There are additional convenience methods for returning all the matches as an array, the total number of matches, the first match, and the range of the first match.
By default, the Block iterator method calls the Block precisely once for each match, with a non-nil?result?and the appropriate?flags. The client may then stop the operation by setting the contents of?stop?to?true. The?stop?argument is an out-only argument. You should only ever set this Boolean to?true?within the Block.
If the?reportProgress?matching option is specified, the Block will also be called periodically during long-running match operations, with?nil?result and?progress?matching flag set in the Block’s?flags?parameter, at which point the client may again stop the operation by setting the contents of stop to?true.?
If the?reportCompletion?matching option is specified, the Block object will be called once after matching is complete, with?nilresult and the?completed?matching flag is set in the?flags?passed to the Block, plus any additional relevant?NSRegularExpression.MatchingFlags?from among?hitEnd,?requiredEnd, or?internalError.?
progress?and?completed?matching flags have no effect for methods other than this method.
The?hitEnd?matching flag is set in the?flags?passed to the Block if the current match operation reached the end of the search range. The?requiredEnd?matching flag is set in the?flags?passed to the Block if the current match depended on the location of the end of the search range.
The?NSRegularExpression.MatchingFlags?matching flag is set in the?flags?passed to the block if matching failed due to an internal error (such as an expression requiring exponential memory allocations) without examining the entire search range.
The?anchored,?withTransparentBounds, and?withoutAnchoringBounds?regular expression options, specified in the?optionsproperty specified when the regular expression instance is created, can apply to any match or replace method.?
If?anchored?matching option is specified, matches are limited to those at the start of the search range.?
If?withTransparentBounds?matching option is specified, matching may examine parts of the string beyond the bounds of the search range, for purposes such as word boundary detection, lookahead, etc.
If?withoutAnchoringBounds?matching option is specified,?^?and?$?will not automatically match the beginning and end of the search range, but will still match the beginning and end of the entire string.?
withTransparentBounds?and?withoutAnchoringBounds?matching options have no effect if the search range covers the entire string.
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
rangeOfFirstMatch(in:options:range:)
numberOfMatches(in:options:range:)
Returns an array containing all the matches of the regular expression in the string.
Declaration
funcmatches(instring:String,options:NSRegularExpression.MatchingOptions= [],range:NSRange) -> [NSTextCheckingResult]
Parameters
string
The string to search.
options
The matching options to use. See?NSRegularExpression.MatchingOptions?for possible values.
range
The range of the string to search.
Return Value
An array of?NSTextCheckingResult?objects. Each result gives the overall matched range via its?range?property, and the range of each individual capture group via its?range(at:)?method. The range {NSNotFound, 0} is returned if one of the capture groups did not participate in this particular match.
Discussion
This is a convenience method that calls?enumerateMatches(in:options:range:using:)?passing the appropriate string, options, and range.
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
rangeOfFirstMatch(in:options:range:)
numberOfMatches(in:options:range:)
enumerateMatches(in:options:range:using:)
Returns the first match of the regular expression within the specified range of the string.
Declaration
funcfirstMatch(instring:String,options:NSRegularExpression.MatchingOptions= [],range:NSRange) ->NSTextCheckingResult?
Parameters
string
The string to search.
options
The matching options to use. See?NSRegularExpression.MatchingOptions?for possible values.
range
The range of the string to search.
Return Value
An?NSTextCheckingResult?object. This result gives the overall matched range via its?range?property, and the range of each individual capture group via its?range(at:)?method. The range {NSNotFound, 0} is returned if one of the capture groups did not participate in this particular match.
Discussion
This is a convenience method that calls?enumerateMatches(in:options:range:using:).
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
rangeOfFirstMatch(in:options:range:)
numberOfMatches(in:options:range:)
enumerateMatches(in:options:range:using:)
Returns the range of the first match of the regular expression within the specified range of the string.
Declaration
funcrangeOfFirstMatch(instring:String,options:NSRegularExpression.MatchingOptions= [],range:NSRange) ->NSRange
Parameters
string
The string to search.
options
The matching options to use. See?NSRegularExpression.MatchingOptions?for possible values.
range
The range of the string to search.
Return Value
The range of the first match. Returns?{NSNotFound, 0}?if no match is found.
Discussion
This is a convenience method that calls?enumerateMatches(in:options:range:using:).
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
numberOfMatches(in:options:range:)
enumerateMatches(in:options:range:using:)
Replacing Strings Using Regular Expressions
Replaces regular expression matches within the mutable string using the template string.
Declaration
funcreplaceMatches(instring:NSMutableString,options:NSRegularExpression.MatchingOptions= [],range:NSRange,withTemplatetempl:String) ->Int
Parameters
string
The mutable string to search and replace values within.
options
The matching options to use. See?NSRegularExpression.MatchingOptions?for possible values.
range
The range of the string to search.
template
The substitution template used when replacing matching instances.
Return Value
The number of matches.
Discussion
See?Flag Options?for the format of?template.
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
stringByReplacingMatches(in:options:range:withTemplate:)
Returns a new string containing matching regular expressions replaced with the template string.
Declaration
funcstringByReplacingMatches(instring:String,options:NSRegularExpression.MatchingOptions= [],range:NSRange,withTemplatetempl:String) ->String
Parameters
string
The string to search for values within.
options
The matching options to use. See?NSRegularExpression.MatchingOptions?for possible values.
range
The range of the string to search.
template
The substitution template used when replacing matching instances.
Return Value
A string with matching regular expressions replaced by the template string.
Discussion
See?Flag Options?for the format of?template.
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
See Also
replaceMatches(in:options:range:withTemplate:)
Escaping Characters in a String
class func?escapedTemplate(for: String) -> String
Returns a template string by adding backslash escapes as necessary to protect any characters that would match as pattern metacharacters
Declaration
classfuncescapedTemplate(forstring:String) ->String
Parameters
string
The template string
Return Value
The escaped template string.
Discussion
Returns a string by adding backslash escapes as necessary to the given string, to escape any characters that would otherwise be treated as pattern metacharacters. You typically use this method to match on a particular string within a larger pattern.
For example, the string?"(N/A)"?contains the pattern metacharacters?(,?/, and?). The result of adding backslash escapes to this string is?"\\(N\\/A\\)".
See?Flag Options?for the format of the resulting template string.
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
class func?escapedPattern(for: String) -> String
Returns a string by adding backslash escapes as necessary to protect any characters that would match as pattern metacharacters.
Declaration
classfuncescapedPattern(forstring:String) ->String
Parameters
string
The string.
Return Value
The escaped string.
Discussion
Returns a string by adding backslash escapes as necessary to the given string, to escape any characters that would otherwise be treated as pattern metacharacters. You typically use this method to match on a particular string within a larger pattern.
For example, the string?"(N/A)"?contains the pattern metacharacters?(,?/, and?). The result of adding backslash escapes to this string is?"\\(N\\/A\\)".
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
Custom Replace Functionality
Used to perform template substitution for a single result for clients implementing their own replace functionality.
Declaration
funcreplacementString(forresult:NSTextCheckingResult,instring:String,offset:Int,templatetempl:String) ->String
Parameters
result
The result of the single match.
string
The string from which the result was matched.
offset
The offset to be added to the location of the result in the string.
template
See?Flag Options?for the format of?template.
Return Value
A replacement string.
Discussion
For clients implementing their own replace functionality, this is a method to perform the template substitution for a single result, given the string from which the result was matched, an offset to be added to the location of the result in the string (for example, in cases that modifications to the string moved the result since it was matched), and a replacement template.
This is an advanced method that is used only if you wanted to iterate through a list of matches yourself and do the template replacement for each one, plus maybe some other calculation that you want to do in code, then you would use this at each step.
Availability
iOS 4.0+
Mac Catalyst 13.0+
macOS 10.7+
tvOS 9.0+
watchOS 2.0+
Constants
struct?NSRegularExpression.Options
These constants define the regular expression options. These constants are used by the property?options,?regularExpressionWithPattern:options:error:, and?init(pattern:options:).
struct?NSRegularExpression.MatchingFlags
Set by the Block as the matching progresses, completes, or fails. Used by the method?enumerateMatches(in:options:range:using:).
struct?NSRegularExpression.MatchingOptions
The matching options constants specify the reporting, completion and matching rules to the expression matching methods. These constants are used by all methods that search for, or replace values, using a regular expression.
Relationships
Inherits From
Conforms To
