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NSDictionary&NSMutableDictionary常用操作梳理

时间:2015-07-27 00:29:56      阅读:118      评论:0      收藏:0      [点我收藏+]

标签:nsdictionary   nsmutabledictionary   

同数组(NSArray),字典类NSDictionary也支持Object Literals,允许我们方便地基于字面量定义初始化字典对象。以下基于字面量语法快捷初始化字典(NSDictionary):

    NSDictionary* literalDictionary = @{@"k1":@"v1", @"k2":@"v2", @"k3":@"v3"};

 1.创建初始化(Initialization&Creation)

1.1 Initializing an Dictionary(NS_DESIGNATED_INITIALIZER)

- (instancetype)init NS_DESIGNATED_INITIALIZER;

// 基于va_list初始化NSDictionary
- (instancetype)initWithObjectsAndKeys:(id)firstObject, ... NS_REQUIRES_NIL_TERMINATION;
// 基于keys数组和对应的values数组初始化NSDictionary
- (instancetype)initWithObjects:(NSArray *)objects forKeys:(NSArray *)keys;
// 基于other Dictionary初始化新的NSDictionary
- (instancetype)initWithDictionary:(NSDictionary *)otherDictionary;
- (instancetype)initWithDictionary:(NSDictionary *)otherDictionary copyItems:(BOOL)flag;

1.2 Creating an Dictionary (autorelease)

+ (instancetype)dictionary;
// 以一对key-value初始化NSDictionary
+ (instancetype)dictionaryWithObject:(id)object forKey:(id <NSCopying>)key;
// initWithObjectsAndKeys:对应的类静态实例化方法
+ (instancetype)dictionaryWithObjectsAndKeys:(id)firstObject, ... NS_REQUIRES_NIL_TERMINATION;
// initWithObjects:forKeys:对应的类静态实例化方法
+ (instancetype)dictionaryWithObjects:(NSArray *)objects forKeys:(NSArray *)keys;
// initWithDictionary:对应的类静态实例化方法
+ (instancetype)dictionaryWithDictionary:(NSDictionary *)dict;

以下是简单的示例:

    NSDictionary* queryItemDict1 = [NSDictionary dictionaryWithObjectsAndKeys:@"v1", @"k1", @"v2", @"k2", @"v3", @"k3", nil];
    NSLog(@"queryItemDict1 = %@", queryItemDict1);
    NSDictionary* queryItemDict2 = [NSDictionary  dictionaryWithObjects:@[@"v1", @"v2", @"v3"] forKeys:@[@"k1", @"k2", @"k3"]];
    NSLog(@"queryItemDict2 = %@", queryItemDict2);

2.访问字典(Querying)

2.1 字典键值对个数

@property (readonly) NSUInteger count;

可以基于dictionary.count对字典进行判空:如果dictionary.count=0,则表示字典为nil或不包含任何键值对。

@property (readonly, copy) NSArray *allKeys; // 所有key的数组
@property (readonly, copy) NSArray *allValues; // 所有value的数组

2.2 键值索引查询

// 查找key对应的value(NSObject)
- (id)objectForKey:(id)aKey;
// 等效于objectForKey,支持中括号下标格式(dictionary[key])访问指定键的值。
- (id)objectForKeyedSubscript:(id)key NS_AVAILABLE(10_8, 6_0);
// 查找value相同的所有keys
- (NSArray *)allKeysForObject:(id)anObject;
// 基于keys数组查找对应的values数组
- (NSArray *)objectsForKeys:(NSArray *)keys notFoundMarker:(id)marker;


3.遍历字典(Enumerate)

- (void)enumerateKeysAndObjectsUsingBlock:(void (^)(id key, id obj, BOOL *stop))block NS_AVAILABLE(10_6, 4_0);

- (NSSet *)keysOfEntriesPassingTest:(BOOL (^)(id key, id obj, BOOL *stop))predicate NS_AVAILABLE(10_6, 4_0);


4.字典排序(Sorting)

keysSortedByValueUsingSelector/keysSortedByValueUsingComparator通过使用指定SELNSComarator来对keyArray进行排序。

- (NSArray *)keysSortedByValueUsingSelector:(SEL)comparator;
- (NSArray *)keysSortedByValueUsingComparator:(NSComparator)cmptr NS_AVAILABLE(10_6, 4_0);


5.可变字典(NSMutableDictionary)

5.1 Initializing an Dictionary(NS_DESIGNATED_INITIALIZER)

除了继承NSDictionary基本的init,还增加了以下指定初始化函数:

- (instancetype)initWithCapacity:(NSUInteger)numItems NS_DESIGNATED_INITIALIZER;
例如,以下代码片段获取URL Components查询串中的queryItem Dictionary:

    // http://weixin.sogou.com/weixin?type=2&ie=utf-8&query=NASA发现新地球
    NSString* wxNASAURLPath = @"http://weixin.sogou.com/weixin?type=2&ie=utf-8&query=NASA%E5%8F%91%E7%8E%B0%E6%96%B0%E5%9C%B0%E7%90%83";
    NSURLComponents* wxNASAURLComponents =  [NSURLComponents componentsWithString:wxNASAURLPath];
    NSMutableDictionary* queryItemDict = [NSMutableDictionary dictionary];
    NSArray* queryItems = wxNASAURLComponents.queryItems;
    for (NSURLQueryItem* item in queryItems) {
        [queryItemDict setObject:item.value forKey:item.name];
    }
    NSLog(@"queryItemDict = %@", queryItemDict);


5.2 setObject for key

// 赋值替换键值对
- (void)setObject:(id)anObject forKey:(id <NSCopying>)aKey;
// 等效于setObject:forKey:,支持中括号下标格式(dictionary[key]=)赋值替换。
- (void)setObject:(id)obj forKeyedSubscript:(id <NSCopying>)key NS_AVAILABLE(10_8, 6_0);


5.3 addEntries & setDictionary

// 从otherDictionary追加entries到当前Dictionary
- (void)addEntriesFromDictionary:(NSDictionary *)otherDictionary;
// 等效于先removeAllObjects后addObjectsFromArray;setDictionary类似于对retain propery的赋值(setter)。
- (void)setDictionary:(NSDictionary *)otherDictionary;


5.4 removeObject

// 删除指定key的键值对
- (void)removeObjectForKey:(id)aKey;
// 删除指定key数组对应的键值对
- (void)removeObjectsForKeys:(NSArray *)keyArray;
// 删除清空所有键值对
- (void)removeAllObjects;


版权声明:本文为博主原创文章,未经博主允许不得转载。

NSDictionary&NSMutableDictionary常用操作梳理

标签:nsdictionary   nsmutabledictionary   

原文地址:http://blog.csdn.net/phunxm/article/details/47072831

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