Question

I am using this code in a loop to populate an NSMutable Array of NSMutableSets (of NSString objects). The index of the NSSet is based on the length of the word.

    // if set of this length not initialized yet, initialize set.
    wordIndex = [NSString stringWithFormat:@"%d", currentWordLength];
    if ([myWordArray objectForKey:wordIndex] == nil)
        [myWordArray setObject:[[NSMutableSet alloc] initWithObjects:currentWord, nil] forKey:wordIndex];
    else
        [[myWordArray objectForKey:wordIndex] addObject:currentWord];

The final intention is to split up an array of words into an array of sets of words grouped by their lengths.

However, I see that [myWordArray count] is 0 after this. Why?

Answer 1

You are confusing the methods of NSMutableDictionary and NSMutableArray: In Objective-C arrays do not have keys but have indexes. If you change the class for myWordArray to NSMutableDicitionary it should work.