如何在NSDictionary内部获取NSArray中的对象数

Question

I need to get a count of the objects in array inside of NSDictionary. For example:

po _dictionary
{
    keys =     (
        "one",
        "two"
    );
}

Taking in consideration this is an array : [_dictionary objectForKey:@"keys"]

my question is how can I get the count in the array?

I try this :

[[[_tutorials objectForKey:@"keys"]  allKeys ]count];

but I'm getting this error:

* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFArray allKeys]: unrecognized selector sent to instance 0xa419ea0'

Answer 1

[_dictionary objectForKey:@"keys"] is an NSArray and not an NSDictionary . Therefore, it doesn't understand the allKeys method. Drop it and it should work:

[[_dictionary objectForKey:@"keys"] count];

Answer 2

NSLog(@"%d", [[_dictionary objectForKey:@"keys"] count]);

由于您的[_dictionary objectForKey:@"keys"]是一个数组，因此您可以直接获取计数。

Answer 3

干得好：

NSLog(@"%lu", _dictionary[@"keys"].count);

Answer 4

NSDictionary有一种获取NSArray键的方法，我发现它比使用objectForKey:更具可读性objectForKey:

[[_dictionary allKeys] count]

Answer 5

  NSDictionary *res=[NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:&error1];

  NSLog(@"%d",[[res valueForKey:@"result"] count]);