字典的创建

一个元素

NSDictionary *dict1 = [NSDictionary dictionaryWithObject: @”rose” forKey: @”name”];

多个元素

NSArray *obj = @[@”rose”, @”USA”];

NSArray *keys = @[@”name”, @”address”];

NSDictionary *dict2 = [NSDictionary dictionaryWithObjects: obj forKeys: keys];

快速创建

NSDictionary *dict3 = @{@”name”: @”rose” , @”qq” : @”756111373”};

访问字典元素

id obj1 = [dict3 objectForKey: @”qq”];

id obj2 = dict3[@”name”];                // 快速访问

计算长度（键值对的个数）

NSUInteger count = dict3.count

可变字典

创建字典

NSMutableDictionary *dict = [NSMutableDictionary dictionary];

添加元素

[dict setObject:@”rose” forKey:@”name”];

[dict setObject:@”USA” forKey:@”address”];

[dict setObject:@”756111373” forKey:@”qq”];

删除元素

[dict removeObjectForKey:@”name”];

打印字典

NSLog(@”%@”, dict1);

遍历字典

使用for循环

NSArray *keys = [dict allKeys];

for(int i = 0; i<dict.count; i++)

{

id obj = [dict objectForKey: keys];

}

使用block

[dict enumerateObjectsAndKeysUsingBlock:

^(id obj, id key, Bool *stop)

{

NSLog(@”%@ : %@”, key, obj);

}];

字典的创建

一个元素

NSDictionary *dict1 = [NSDictionary dictionaryWithObject: @”rose” forKey: @”name”];

多个元素

NSArray *obj = @[@”rose”, @”USA”];

NSArray *keys = @[@”name”, @”address”];

NSDictionary *dict2 = [NSDictionary dictionaryWithObjects: obj forKeys: keys];

快速创建

NSDictionary *dict3 = @{@”name”: @”rose” , @”qq” : @”756111373”};

访问字典元素

id obj1 = [dict3 objectForKey: @”qq”];

id obj2 = dict3[@”name”];                // 快速访问

计算长度（键值对的个数）

NSUInteger count = dict3.count

可变字典

创建字典

NSMutableDictionary *dict = [NSMutableDictionary dictionary];

添加元素

[dict setObject:@”rose” forKey:@”name”];

[dict setObject:@”USA” forKey:@”address”];

[dict setObject:@”756111373” forKey:@”qq”];

删除元素

[dict removeObjectForKey:@”name”];

打印字典

NSLog(@”%@”, dict1);

遍历字典

使用for循环

NSArray *keys = [dict allKeys];

for(int i = 0; i<dict.count; i++)

{

id obj = [dict objectForKey: keys];

}

使用block

[dict enumerateObjectsAndKeysUsingBlock:

^(id obj, id key, Bool *stop)

{

NSLog(@”%@ : %@”, key, obj);

}];