Question

I am making an app that has a king of “update method” that is responsible for running code continually. I thought of using an NSTimer as it has an option to have it repeat indefinitely. I have it load as such:

gameTimer = [NSTimer timerWithTimeInterval:0.01428 target:self selector:@selector(GameUpdate:) userInfo:NULL repeats:true];

Where the GameUpdate: declaration is like so:

-(void)GameUpdate:(NSTimer*)timer;

The thing is, the code inside GameUpdate: never runs. It used to work in xcode 4.2. Why is this?

Answer 1

You need to add your newly created NSTimer object to the run loop.

(lifted from the answer to this related question): As the docs say:

Timers work in conjunction with run loops. To use a timer effectively,
you should be aware of how run loops operate—see NSRunLoop and
Threading Programming Guide. Note in particular that run loops retain
their timers, so you can release a timer after you have added it to a
run loop.

If you look at the other answers to that related question, you’ll see how to create a NSTimer object where it gets automatically added to the run loop.