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

 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];

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]);

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);

    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];

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

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];

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"];

    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"];

    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];