iOS学习路之Objective-C（六）—— NSDictionary和NSMutableDictionary

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1. 创建一个不可变的字典

    1     //字典中的元素是成对出现的,key-value,key(键，索引),value(值，索引对应的值),两者均是id对象
    2     NSDictionary *dictionary = @{@"key":@"value", @"key2":@"value2"};
    3 #if 0
    4 #pragma mark 对象方法
    5     NSDictionary *dictionary1 = [[NSDictionary alloc] initWithDictionary:dictionary];
    6     NSDictionary *dictionary2 = [[NSDictionary alloc] initWithObjectsAndKeys:@"key",@"value", @"key2", @"value2", nil];
    7 #endif
    8     
    9 #pragma mark 类方法
   10     NSDictionary *dictionary1 = [NSDictionary dictionaryWithDictionary:dictionary];
   11     NSDictionary *dictionary2 = [NSDictionary dictionaryWithObjectsAndKeys:@"key",@"value", @"key2", @"value2", nil];

    

2. 获取字典中元素的个数

   1     NSDictionary *dictionary = @{@"key":@"value", @"key2":@"value2"};
   2     //@property (readonly) NSUInteger count;
   3     //作用：获取字典键值对的个数
   4     NSLog(@"%lu", [dictionary count]);

    

3. 通过键找对应的值

   1     NSDictionary *dictionary = @{@"key":@"value", @"key2":@"value2"};
   2     //- (id)objectForKey:(id)aKey;
   3     //作用：通过键值寻找Value
   4     NSString *string = [dictionary objectForKey:@"key"];
   5     NSLog(@"%@", string);

    

4. 获取字典中所有的key

       NSDictionary *dictionary = @{@"key":@"value", @"key2":@"value2"};
       //@property (readonly, copy) NSArray *allKeys;
       //作用：获取字典中所有的key
       NSArray *array = [dictionary allKeys];

    

5. 获取字典中所有的value

       NSDictionary *dictionary = @{@"key":@"value", @"key2":@"value2"};
       //@property (readonly, copy) NSArray *allValues;
       //作用：获取所有的Value
       NSArray *array = [dictionary allValues];

    

6. 创建一个可变的字典

   1 #pragma mark 对象方法
   2     NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] initWithCapacity:0];
   3 #pragma mark 类方法
   4     NSMutableDictionary *dictionary1 = [NSMutableDictionary dictionaryWithCapacity:0];

    

7. 向字典中追加键值对

   1     NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithCapacity:0];
   2     //- (void)setObject:(id)anObject forKey:(id <NSCopying>)aKey;
   3     //作用：当key值在字典中已经存在，可以对键值对进行替换，如果不存在，就追加在字典尾部
   4     [dictionary setObject:@"value" forKey:@"key"];
   5     [dictionary setObject:@"value2" forKey:@"key2"];

    

8. 删除字典中的键值

       NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithCapacity:0];
       [dictionary setObject:@"chen chao" forKey:@"namel"];
       [dictionary setObject:@"183" forKey:@"height"];
       [dictionary setObject:@"shuai" forKey:@"info"];
       //- (void)removeObjectForKey:(id)aKey;
       //作用：删除key对应的键值对
       [dictionary removeObjectForKey:@"info"];

    

9. 修改字典

       NSDictionary *dic = @{@"key":@"value", @"key2":@"value2"};
       NSMutableDictionary *dictionary = [NSMutableDictionary dictionaryWithCapacity:0];
       [dictionary setObject:@"chen chao" forKey:@"namel"];
       [dictionary setObject:@"183" forKey:@"height"];
       [dictionary setObject:@"shuai" forKey:@"info"];
       //- (void)setDictionary:(NSDictionary *)otherDictionary;
       //作用：将当前字典用另一个字典替换
       [dictionary setDictionary:dic];

    

iOS学习路之Objective-C（六）—— NSDictionary和NSMutableDictionary

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原文地址：http://www.cnblogs.com/dyikai/p/4499316.html