Global variables/singletons?

Question

I have an audio/music based application where there are various views.

In one view there is a sequencer, another view has drum pads and the other view has buttons to record and play the recorded audio.

I had initially set up these screens so that they each have their own class files but have realised that I want to be able to control the playback of the sequencer from the other views.

currently the app just has views with buttons to segue (show) to the other view controllers. Whilst the sequencer is playing, I am currently able to still hear the audio from the sequencer however the playback buttons for it are only in that screen; when i return to the sequencer view the data from the previous initialisation is gone and I can no longer stop the audio from playing.

I've been told I need to create a singleton/NSObject file but I wasn't given much detail into how to do this and haven't found much online that can help my specific case. I tried turning the sequencer's view controller into a container view, and then having the playback buttons in the main view above the child view container but no luck.

Does anyone know how to help?

score -1 · Answer 1 · answered Dec 07 '16 at 20:50

-1

Init a singleton like this:

static id _sharedSingleton = nil;
+ (id) sharedInstance {
    if (_sharedSingleton) 
        return _sharedSingleton;
    @synchronized(self) {
        if (    !    _sharedSingleton) {
            _sharedSingleton = [[self alloc] init];
        }
    }
    return _sharedSingleton;
}

answered Dec 07 '16 at 20:50

KugelnMMXVI

165
8

How do I put a function into the singleton? i.e. so that when I use a button in the other view controller, it calls the function from the singleton object file? – Klaus Dec 07 '16 at 23:59
This is not the best way to implement a singleton. – rmaddy Dec 08 '16 at 00:18

Global variables/singletons?

1 Answers1