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iOS Build a Playlist Browser with Objective-C Managing Playlist Data Using Helper Methods

Posted by Kunakorn Puntawong
Kunakorn Puntawong
3,016 Points

Why do I need arrayWithArray method in this case

The instructor wrote:

_playlistArtists = [NSArray arrayWithArray: [playDictionary objectForKey:kArtist]];

The [playDIctionary objectForKey:kArtist] already returns an array. So, why do I still need arrayWithArray method ? why can't I do something like this:

_playlistArtists =[playDictionary objectForKey:kArtist];

Darean Wong
Darean Wong
Courses Plus Student 4,186 Points
Darean Wong
Darean Wong
Courses Plus Student 4,186 Points

I have this question too. Can someone please let us know why?

1 Answer

Madhav Sharma
Madhav Sharma
4,081 Points
Madhav Sharma
Madhav Sharma
4,081 Points

Your question is a very good example in understanding 'pointers'. If we set it equal like how you did, we would set the pointer '_playlistArtists' to the same address contained in 'playlistDictionary' (which is contained in property 'library' of the object 'musicLibrary') . Because we declared the property '_playlistArtists' as a strong reference, it will still work because the pointers created in the method won't be there after execution.

But I guess, it is just more intuitive to allocate a separate, new array which is a copy of the last one as the permanent one we will keep to store our data.