OC集合類之NSDictionary、NSMutableDictionary（二）

一、NSDictionary（不可變字典）

概述：

在編程中，字典（dictionary）是關鍵字及其定義的集合。NSDictionary是Cocoa中的一個集合類，它能在給定的關鍵字（通常是一個NSString字符串）下存儲一個數(shù)值（可以是任何類型的OC對象），然后根據(jù)這個關鍵字來查找相應的數(shù)據(jù)。

實例方法：


//根據(jù)key查找akey對應的值

- (nullableObjectType)objectForKey:(KeyType)aKey;

//獲取字典所有鍵值

- (NSEnumerator *)keyEnumerator;

//初始化字典

- (instancetype)init NS_DESIGNATED_INITIALIZER;

//初始化字典（根據(jù)不同的編譯條件）

#if TARGET_OS_WIN32

- (instancetype)initWithObjects:(constObjectType_Nonnull[_Nullable])objects forKeys:(constKeyType_Nonnull[_Nullable])keys count:(NSUInteger)cnt;

#else

- (instancetype)initWithObjects:(constObjectType_Nonnull[_Nullable])objects forKeys:(constKeyType_Nonnull[_Nullable])keys count:(NSUInteger)cntNS_DESIGNATED_INITIALIZER;

#endif

- (nullableinstancetype)initWithCoder:(NSCoder*)aDecoderNS_DESIGNATED_INITIALIZER;

//根據(jù)所填入的object返回對應所有的key鍵值

- (NSArray *)allKeysForObject:(ObjectType)anObject;

//根據(jù)設置的locale進行連接數(shù)組

- (NSString*)descriptionWithLocale:(nullableid)locale;

//根據(jù)設置的locale進行連接數(shù)組

- (NSString*)descriptionWithLocale:(nullableid)locale indent:(NSUInteger)level;

//字典判斷

- (BOOL)isEqualToDictionary:(NSDictionary *)otherDictionary;

//獲取字典所有對象值

- (NSEnumerator *)objectEnumerator;

//字典將某個特定的數(shù)組作為key值傳進去得到對應的value，如果某個key找不到對應的key，就用notFoundMarker提前設定的值代替

- (NSArray *)objectsForKeys:(NSArray *)keys notFoundMarker:(ObjectType)marker;

//將字典序列化為NSRabryType格式中指定的URL

- (BOOL)writeToURL:(NSURL*)url error:(NSError**)errorAPI_AVAILABLE(macos(10.13), ios(11.0), watchos(4.0), tvos(11.0));

//排序

- (NSArray *)keysSortedByValueUsingSelector:(SEL)comparator;

- (void)getObjects:(ObjectType_Nonnull__unsafe_unretained[_Nullable])objects andKeys:(KeyType_Nonnull__unsafe_unretained[_Nullable])keys count:(NSUInteger)countAPI_AVAILABLE(macos(10.7), ios(5.0), watchos(2.0), tvos(9.0))NS_SWIFT_UNAVAILABLE("Use 'allKeys' and/or 'allValues' instead");

//以數(shù)組下標的形式來訪問相應鍵的值

- (nullableObjectType)objectForKeyedSubscript:(KeyType)keyAPI_AVAILABLE(macos(10.8), ios(6.0), watchos(2.0), tvos(9.0));

//利用block對字典進行遍歷

- (void)enumerateKeysAndObjectsUsingBlock:(void(NS_NOESCAPE^)(KeyType key, ObjectType obj,BOOL*stop))blockAPI_AVAILABLE(macos(10.6), ios(4.0), watchos(2.0), tvos(9.0));

//利用block對字典進行遍歷(添加正序反序遍歷)

- (void)enumerateKeysAndObjectsWithOptions:(NSEnumerationOptions)opts usingBlock:(void(NS_NOESCAPE^)(KeyType key, ObjectType obj,BOOL*stop))blockAPI_AVAILABLE(macos(10.6), ios(4.0), watchos(2.0), tvos(9.0));

//根據(jù)NSComparato參數(shù)條件排序

- (NSArray *)keysSortedByValueUsingComparator:(NSComparatorNS_NOESCAPE)cmptrAPI_AVAILABLE(macos(10.6), ios(4.0), watchos(2.0), tvos(9.0));

//根據(jù)NSComparato參數(shù)條件排序

- (NSArray *)keysSortedByValueWithOptions:(NSSortOptions)opts usingComparator:(NSComparatorNS_NOESCAPE)cmptrAPI_AVAILABLE(macos(10.6), ios(4.0), watchos(2.0), tvos(9.0));

//過濾的方法

- (NSSet *)keysOfEntriesPassingTest:(BOOL(NS_NOESCAPE^)(KeyType key, ObjectType obj,BOOL*stop))predicateAPI_AVAILABLE(macos(10.6), ios(4.0), watchos(2.0), tvos(9.0));

//過濾的方法

- (NSSet *)keysOfEntriesWithOptions:(NSEnumerationOptions)opts passingTest:(BOOL(NS_NOESCAPE^)(KeyType key, ObjectType obj,BOOL*stop))predicateAPI_AVAILABLE(macos(10.6), ios(4.0), watchos(2.0), tvos(9.0));

//根據(jù)文件創(chuàng)建字典

- (nullableNSDictionary *)initWithContentsOfFile:(NSString*)path;

//根據(jù)url創(chuàng)建字典

- (nullableNSDictionary *)initWithContentsOfURL:(NSURL*)url;

//將字典寫進特定的路徑path

- (BOOL)writeToFile:(NSString*)path atomically:(BOOL)useAuxiliaryFile;

//將字典寫進特定的url

- (BOOL)writeToURL:(NSURL*)url atomically:(BOOL)atomically; 

//使用指定的以nil為結尾的對象與鍵對列表初始化列表

- (instancetype)initWithObjectsAndKeys:(id)firstObject, ...NS_REQUIRES_NIL_TERMINATION;

//使用另一個字典初始化字典

- (instancetype)initWithDictionary:(NSDictionary *)otherDictionary;

//使用另一個字典初始化字典，還可以為每個對象創(chuàng)建新的副本

- (instancetype)initWithDictionary:(NSDictionary *)otherDictionary copyItems:(BOOL)flag;

//初始化

- (instancetype)initWithObjects:(NSArray *)objects forKeys:(NSArray> *)keys;

//從指定的URL讀取存儲在NSpRealType格式中的字典

- (nullableNSDictionary *)initWithContentsOfURL:(NSURL*)url error:(NSError**)errorAPI_AVAILABLE(macos(10.13), ios(11.0), watchos(4.0), tvos(11.0));

類方法：


//根據(jù)path路徑獲取字典信息

+ (nullableNSDictionary *)dictionaryWithContentsOfFile:(NSString*)path;

//根據(jù)url地址獲取字典信息

+ (nullableNSDictionary *)dictionaryWithContentsOfURL:(NSURL*)url;

//創(chuàng)建字典并賦值

+ (instancetype)dictionaryWithObject:(ObjectType)object forKey:(KeyType)key;

//創(chuàng)建字典（根據(jù)不同編譯環(huán)境）

#if TARGET_OS_WIN32

+ (instancetype)dictionaryWithObjects:(constObjectType_Nonnull[_Nullable])objects forKeys:(constKeyType_Nonnull[_Nullable])keys count:(NSUInteger)cnt;

#else

+ (instancetype)dictionaryWithObjects:(constObjectType_Nonnull[_Nullable])objects forKeys:(constKeyType_Nonnull[_Nullable])keys count:(NSUInteger)cnt;

#endif

+ (instancetype)dictionaryWithObjectsAndKeys:(id)firstObject, ...NS_REQUIRES_NIL_TERMINATIONNS_SWIFT_UNAVAILABLE("Use dictionary literals instead");

//創(chuàng)建字典并賦值一個字典

+ (instancetype)dictionaryWithDictionary:(NSDictionary *)dict;

//創(chuàng)建字典并通過數(shù)組賦值

+ (instancetype)dictionaryWithObjects:(NSArray *)objects forKeys:(NSArray> *)keys;

//從指定的URL讀取存儲在NSpRealType格式中的字典

+ (nullableNSDictionary *)dictionaryWithContentsOfURL:(NSURL*)url error:(NSError**)errorAPI_AVAILABLE(macos(10.13), ios(11.0), watchos(4.0), tvos(11.0))NS_SWIFT_UNAVAILABLE("Use initializer instead");

//用來創(chuàng)建預訂好的key集合，返回的值作為NSMutableDictionary的dictionaryWithSharesKeySet參數(shù)傳入，可以重用key，從而節(jié)約copy操作，節(jié)省內存

+ (id)sharedKeySetForKeys:(NSArray> *)keysAPI_AVAILABLE(macos(10.8), ios(6.0), watchos(2.0), tvos(9.0));

//創(chuàng)建字典，共享鍵集會復用對象

+ (NSMutableDictionary *)dictionaryWithSharedKeySet:(id)keysetAPI_AVAILABLE(macos(10.8), ios(6.0), watchos(2.0), tvos(9.0));

二、NSMutableDictionary（可變字典）

概述：

和NSString和NSArray一樣，NSDictionary對象是不可變。NSMutableDictionary繼承至NSDictionary，允許我們隨意添加、刪除元素。

實例方法：


//刪除字典對應key值的元素

- (void)removeObjectForKey:(KeyType)aKey;

//添加元素（anObject為要添加的元素，aKey為對應的key值）

- (void)setObject:(ObjectType)anObject forKey:(KeyType)aKey;

//初始化

- (instancetype)init NS_DESIGNATED_INITIALIZER;

//指定初始化函數(shù)

- (instancetype)initWithCapacity:(NSUInteger)numItemsNS_DESIGNATED_INITIALIZER;

- (nullableinstancetype)initWithCoder:(NSCoder*)aDecoderNS_DESIGNATED_INITIALIZER;

//字典拼接

- (void)addEntriesFromDictionary:(NSDictionary *)otherDictionary;

//刪除字典

- (void)removeAllObjects;

//移除由keyArray的元素指定的key的所有數(shù)據(jù)

- (void)removeObjectsForKeys:(NSArray *)keyArray;

//設置字典內容為otherDictionary

- (void)setDictionary:(NSDictionary *)otherDictionary;

//前綴下標方法

- (void)setObject:(nullableObjectType)obj forKeyedSubscript:(KeyType)keyAPI_AVAILABLE(macos(10.8), ios(6.0), watchos(2.0), tvos(9.0));

//根據(jù)文件創(chuàng)建字典

- (nullableNSMutableDictionary *)initWithContentsOfFile:(NSString*)path;

//根據(jù)url創(chuàng)建字典

- (nullableNSMutableDictionary *)initWithContentsOfURL:(NSURL*)url;

類方法：


//初始化一個空間大小的字典(NSUInteger代表了開辟內存的一個單位)

+ (instancetype)dictionaryWithCapacity:(NSUInteger)numItems;

//根據(jù)文件獲取字典信息

+ (nullableNSMutableDictionary *)dictionaryWithContentsOfFile:(NSString*)path;

//根據(jù)url地址獲取字典信息

+ (nullableNSMutableDictionary *)dictionaryWithContentsOfURL:(NSURL*)url;

說明：

字典（也被稱為散列表或關聯(lián)數(shù)組）使用的是鍵查詢的優(yōu)化方式。它可以立即找出要查詢的數(shù)據(jù)，而不需要遍歷整個數(shù)組。對應大型的數(shù)據(jù)集來說，使用字典比數(shù)組要快得多，所以，這就是我們不用數(shù)組來存儲然后查詢的原因。

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