Question

I’ve been using an NSTimer successfully, but am now having trouble with it. Undoubtably something stupid. Appreciate another set of eyes. Running the debugger, I see that applicationDidFinishLaunching is called, but trigger is never called.

-(void) trigger:(NSTimer *) theTimer{
    NSLog(@"timer fired");
}

- (void)applicationDidFinishLaunching:(UIApplication *)application {    

    nst = [NSTimer timerWithTimeInterval:1.0 target:self selector:@selector(trigger) userInfo:nil repeats:YES];

    [window makeKeyAndVisible];
}

Answer 1

The selector must have the following signature:

- (void)timerFireMethod:(NSTimer*)theTimer

so you need

@selector(trigger:)

–edit–

Maybe you are doing this somewhere else, but in the code you included you do not actually start the timer. You have to add it to a NSRunLoop before it can trigger any events at all.

 [[NSRunLoop currentRunLoop] addTimer:nst forMode:NSDefaultRunLoopMode];

If I read the examples correctly. I’ve only used the one the init method that automatically adds it to the current NSRunLoop. You really should look at the developer docs that someone included in the comments to my post.