Question

How to do that without having to “scroll” the entire given array with a “for” loop?

Answer 1

_{Since nobody seems to agree with my comment that this is a duplicate of Better way to convert NSArray of NSNumbers to array of NSStrings, here’s the same answer again:}

NSArray * arrayOfMutableStrings = [arrayOfStrings valueForKey:@"mutableCopy"];

From the docs:

valueForKey:
Returns an array containing the results of invoking
valueForKey: using key on each of the array’s objects.

- (id)valueForKey:(NSString *)key

Parameters
key The key to retrieve.

Return Value
The value of the retrieved key.

Discussion
The returned array contains NSNull elements for each object that returns nil.