一、NSError是系統(tǒng)錯誤信息類
//兩種初始化方法：其中，domain 不能為空 dict可以為空
- (instancetype)initWithDomain:(NSErrorDomain)domain code:(NSInteger)code userInfo:(nullable NSDictionary *)dict;
+ (instancetype)errorWithDomain:(NSErrorDomain)domain code:(NSInteger)code userInfo:(nullable NSDictionary *)dict;
@property (readonly, copy) NSErrorDomain domain;//錯誤域
錯誤域主要有四個，對于Carbon框架的Error，歸于OSStatus domain（NSOSStatusErrorDomain），對于POSIX error，歸于NSPOSIXErrorDomain，而對于我們的iOS開發(fā)，一般使用NSCocoaErrorDomain。NSError.h定義了四個domain
{
// Predefined domain for errors from most AppKit and Foundation APIs.
FOUNDATION_EXPORT NSErrorDomain const NSCocoaErrorDomain;
// Other predefined domains; value of "code" will correspond to preexisting values in these domains.
FOUNDATION_EXPORT NSErrorDomain const NSPOSIXErrorDomain;
FOUNDATION_EXPORT NSErrorDomain const NSOSStatusErrorDomain;
FOUNDATION_EXPORT NSErrorDomain const NSMachErrorDomain;
}
@property (readonly) NSInteger code;//錯誤代碼
@property (readonly, copy) NSDictionary *userInfo;//錯誤信息
@property (readonly, copy) NSString *localizedDescription;//獲取本地化描述
@property (nullable, readonly, copy) NSString *localizedFailureReason;//獲取失敗原因
@property (nullable, readonly, copy) NSString *localizedRecoverySuggestion;//獲取恢復建議
@property (nullable, readonly, copy) NSArray *localizedRecoveryOptions;本地恢復建議
@property (nullable, readonly, strong) id recoveryAttempter;
@property (nullable, readonly, copy) NSString *helpAnchor;
預定義的userinfo鍵名
NSString *const NSUnderlyingErrorKey;//推薦的標準方式，通用鍵
NSString *const NSLocalizedDescriptionKey;???????????? //?詳細描述鍵
NSString *const NSLocalizedFailureReasonErrorKey;????? // 失敗原因鍵
NSString *const NSLocalizedRecoverySuggestionErrorKey; //恢復建議鍵
NSString *const NSLocalizedRecoveryOptionsErrorKey;??? // 恢復選項鍵
//其他鍵
NSString *const NSRecoveryAttempterErrorKey;?
NSString *const NSHelpAnchorErrorKey;?
NSString *const NSStringEncodingErrorKey ;?
NSString *const NSURLErrorKey;?
NSString *const NSFilePathErrorKey;?
用法示例：
NSDictionary *userInfo1 = [NSDictionary dictionaryWithObjectsAndKeys:@"由于文件不存在，無法打開", NSLocalizedDescriptionKey, @"失敗原因：文件不存在", NSLocalizedFailureReasonErrorKey, @"恢復建議：請創(chuàng)建該文件",NSLocalizedRecoverySuggestionErrorKey,nil];
NSError *error = [[NSError alloc] initWithDomain:NSCocoaErrorDomain code:4 userInfo:userInfo1];//此處code是4，對照下面對照表4代表文件不存在。userinfo傳userinfo1 查看自定義打印。userinfo傳nil，查看本地化描述。
NSLog(@"========%@",[error localizedDescription]);
NSLog(@"========%@",[error localizedFailureReason]);
NSLog(@"========%@",[error localizedRecoverySuggestion]);
二、NSError錯誤code對照表
Foundation Constants Reference
NSError Codes
NSError codes in the Cocoa error domain.
enum {
NSFileNoSuchFileError = 4,
NSFileLockingError = 255,
NSFileReadUnknownError = 256,
NSFileReadNoPermissionError = 257,
NSFileReadInvalidFileNameError = 258,
NSFileReadCorruptFileError = 259,
NSFileReadNoSuchFileError = 260,
NSFileReadInapplicableStringEncodingError = 261,
NSFileReadUnsupportedSchemeError = 262,
NSFileReadTooLargeError = 263,
NSFileReadUnknownStringEncodingError = 264,
NSFileWriteUnknownError = 512,
NSFileWriteNoPermissionError = 513,
NSFileWriteInvalidFileNameError = 514,
NSFileWriteInapplicableStringEncodingError = 517,
NSFileWriteUnsupportedSchemeError = 518,
NSFileWriteOutOfSpaceError = 640,
NSFileWriteVolumeReadOnlyError = 642m
NSKeyValueValidationError = 1024,
NSFormattingError = 2048,
NSUserCancelledError = 3072,
NSFileErrorMinimum = 0,
NSFileErrorMaximum = 1023,
NSValidationErrorMinimum = 1024,
NSValidationErrorMaximum = 2047,
NSFormattingErrorMinimum = 2048,
NSFormattingErrorMaximum = 2559,
NSPropertyListReadCorruptError = 3840,
NSPropertyListReadUnknownVersionError = 3841,
NSPropertyListReadStreamError = 3842,
NSPropertyListWriteStreamError = 3851,
NSPropertyListErrorMinimum = 3840,
NSPropertyListErrorMaximum = 4095
NSExecutableErrorMinimum = 3584,
NSExecutableNotLoadableError = 3584,
NSExecutableArchitectureMismatchError = 3585,
NSExecutableRuntimeMismatchError = 3586,
NSExecutableLoadError = 3587,
NSExecutableLinkError = 3588,
NSExecutableErrorMaximum = 3839,
}
URL Loading System Error Codes
These values are returned as the error code property of an NSError object with the domain “NSURLErrorDomain”.
typedef enum
{
NSURLErrorUnknown = -1,
NSURLErrorCancelled = -999,
NSURLErrorBadURL = -1000,
NSURLErrorTimedOut = -1001,
NSURLErrorUnsupportedURL = -1002,
NSURLErrorCannotFindHost = -1003,
NSURLErrorCannotConnectToHost = -1004,
NSURLErrorDataLengthExceedsMaximum = -1103,
NSURLErrorNetworkConnectionLost = -1005,
NSURLErrorDNSLookupFailed = -1006,
NSURLErrorHTTPTooManyRedirects = -1007,
NSURLErrorResourceUnavailable = -1008,
NSURLErrorNotConnectedToInternet = -1009,
NSURLErrorRedirectToNonExistentLocation = -1010,
NSURLErrorBadServerResponse = -1011,
NSURLErrorUserCancelledAuthentication = -1012,
NSURLErrorUserAuthenticationRequired = -1013,
NSURLErrorZeroByteResource = -1014,
NSURLErrorCannotDecodeRawData = -1015,
NSURLErrorCannotDecodeContentData = -1016,
NSURLErrorCannotParseResponse = -1017,
NSURLErrorFileDoesNotExist = -1100,
NSURLErrorFileIsDirectory = -1101,
NSURLErrorNoPermissionsToReadFile = -1102,
NSURLErrorSecureConnectionFailed = -1200,
NSURLErrorServerCertificateHasBadDate = -1201,
NSURLErrorServerCertificateUntrusted = -1202,
NSURLErrorServerCertificateHasUnknownRoot = -1203,
NSURLErrorServerCertificateNotYetValid = -1204,
NSURLErrorClientCertificateRejected = -1205,
NSURLErrorClientCertificateRequired = -1206,
NSURLErrorCannotLoadFromNetwork = -2000,
NSURLErrorCannotCreateFile = -3000,
NSURLErrorCannotOpenFile = -3001,
NSURLErrorCannotCloseFile = -3002,
NSURLErrorCannotWriteToFile = -3003,
NSURLErrorCannotRemoveFile = -3004,
NSURLErrorCannotMoveFile = -3005,
NSURLErrorDownloadDecodingFailedMidStream = -3006,
NSURLErrorDownloadDecodingFailedToComplete = -3007
}
三、自定義NSError
系統(tǒng)的NSError是可以自己定制的，以下提供代碼來實現(xiàn)并表示如何使用：
YXError.h 與?YXError.m
[objc]?view plain?copy
//??
//??YXError.h??
//??CustomYXError??
//??
//??Copyright?(c)?2014年?Y.X.?All?rights?reserved.??
//??
#import???
//?自行添加錯誤碼??
typedef?enum?:?NSUInteger?{??
Crash?????=?-10000,??
??DisConnect,??
??Unknow,??
}?YXErrorCode;??
@interface?YXError?:?NSObject??
+?(NSError?*)errorCode:(YXErrorCode)code?userInfo:(NSDictionary?*)dic;??
+?(NSString?*)transformCodeToStringInfo:(YXErrorCode)code;??
@end??
[objc]?view plain?copy
//??
//??YXError.m??
//??CustomYXError??
//??
//??Copyright?(c)?2014年?Y.X.?All?rights?reserved.??
//??
#import?"YXError.h"??
static?NSDictionary?*errorDictionary?=?nil;??
@implementation?YXError??
+?(void)initialize??
{??
if?(self?==?[YXError?class])??
????{??
????????errorDictionary?=?\??
????????@{??
/*?code????????:????????errorWithDomain?*/??
/*?====================================?*/??
@(Crash)???????:@"Crash",??
@(DisConnect)??:@"DisConnect",??
@(Unknow)??????:@"Unknow",??
/*?====================================?*/??
??????????};??
????}??
}??
+?(NSError?*)errorCode:(YXErrorCode)code?userInfo:(NSDictionary?*)dic??
{??
return?[NSError?errorWithDomain:errorDictionary[@(code)]??
?code:code??
?userInfo:dic];??
}??
+?(NSString?*)transformCodeToStringInfo:(YXErrorCode)code??
{??
return?errorDictionary[@(code)];??
}??
@end??
以下是使用的代碼：
[objc]?view plain?copy
//??
//??AppDelegate.m??
//??NSError??
//??
//??Copyright?(c)?2014年?YouXianMing.?All?rights?reserved.??
//??
#import?"AppDelegate.h"??
#import?"YXError.h"??
@implementation?AppDelegate??
-?(BOOL)application:(UIApplication?*)application?didFinishLaunchingWithOptions:(NSDictionary?*)launchOptions??
{??
//?定制一個NSError??
NSError?*error?=?[YXError?errorCode:Crash??
?userInfo:nil];??
NSLog(@"%@",?error);??
//?翻譯一個NSError（將code值翻譯成字符串）??
NSLog(@"%@",?[YXError?transformCodeToStringInfo:-10000]);??
return?YES;??
}??
@end??
