Foundation_NSDictionary

取值注意点：

根据键找值。如果是基本数据类型，用valueForKey:

如果是对象，用objectForKey:

NSDictionary * dic = @{@"@":@"@"};
    NSLog(@"%@",dic);
    
    NSDictionary * dic2 = @{@"%" : @"%"};
    
    NSString * string = [dic2 objectForKey:@"%"];
    NSLog(@"string=%@",string);

字典是无序的，数组是有序的

    NSDictionary * dict = @{@"name":@"rose",@"sex":@"F",@"age":@"16"};
    //如果是以下写法，key－value 将会是Jacky－name
    NSDictionary * dictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"name",@"Jacky",@"sex",@"M",@"age",@"18",nil];
    NSLog(@"%@",dictionary);
    NSDictionary * dic = [NSDictionary dictionaryWithDictionary:dict];
    NSLog(@"%@",dic);
    
    
    NSMutableDictionary * mutableDic = [NSMutableDictionary dictionary];
    //NSMutableDictionary * mutableDic1 = [NSMutableDictionary dictionaryWithCapacity:10];
    [mutableDic setObject:@"Sylvia" forKey:@"name"];
    [mutableDic setObject:@"F" forKey:@"sex"];
    [mutableDic setObject:@"24" forKey:@"age"];
    
    [mutableDic removeObjectForKey:@"age"];
     NSLog(@"%@",mutableDic);
    [mutableDic removeAllObjects];
    NSLog(@"%@",mutableDic);