字典

靜態字典

初始化

NSDictionary * dict = [NSDictionary dictionary];
dict = [NSDictionary dictionaryWithObjectsAndKeys:@"yc",@"name",@18,@"age", nil];
NSLog(@"%@",dict);
dict = @{@"name":@"yc",@"age":@20};
NSLog(@"%@",dict);

數量

NSLog(@"%i",[dict count]);

訪問數組中的元素

NSString * name = [dict objectForKey:@"name"];
NSNumber * ageNumber = [dict objectForKey:@"age"];//注意這裏是NSNumber類型
int age = [ageNumber intValue];//NSNumber轉int
NSLog(@"%@,%i",name,age);

遍歷key

for (NSObject * key in [dict keyEnumerator]) {
    NSLog(@"key=%@,value=%@",key,[dict objectForKey:key]);
}

遍歷value

for(NSObject * obj in [dict objectEnumerator])
{
    NSArray * keys = [dict allKeysForObject:obj];//注意這裏是數組，因爲一個值可能對應多個key
    NSLog(@"value=%@,keys=%@",obj,keys);
}

遍歷key和value

[dict enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
    NSLog(@"key=%@,value=%@",key,obj);
}];

動態字典

初始化空字典

NSMutableDictionary * dict = [NSMutableDictionary dictionary];

設置

[dict setObject:@"yc" forKey:@"name"];
[dict setObject:@18 forKey:@"age"];
[dict setObject:@20 forKey:@"age"];
[dict setObject:@"man" forKey:@"sex"];
NSLog(@"%@",dict);

移除

[dict removeObjectForKey:@"sex"];
NSLog(@"%@",dict);