NSTimer freezes the app until it gets fired again?

Question

I have a simple app with a button, UIImageView and a NSTimer. The timer is fired up every 5 seconds repeatedly to update the ImageView with a new image, while the button simply stops the timer and switches to another View.

The problem is that when I press the button, nothing happens for a few seconds (until the timer fires up again).

Is there a way to cause the button to stop the timer and do its job at any given time instead of between intervals of the timer?

The button is defined in the InterfaceBuilder and connected to a function in the code.

The NSTimer code: (I've tried with & without adding it to the RunLoop).

updateTimer = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector:@selector(updateImageViews) userInfo:nil repeats:YES];

NSRunLoop* runLoop = [NSRunLoop currentRunLoop];
[[NSRunLoop currentRunLoop] addTimer:updateTimer forMode:NSDefaultRunLoopMode];
[runLoop run];

Thanks!

are you using invalidate to stop the timer...? can you put some code...? — Mihir Mehta
I've added the timer code, And Yes, I use invalidate to stop the timer in the function that's being called when the button is pressed. thanks — itai alter
When you say "nothing happens" do you mean the next view does not appear? Does the view appear when the timer fires? Not really clear what the problem is. What to want to see and what to you actually see? — TechZen
What I mean is that the button (and all of the mainview) is Inactive (frozen) when the NSTimer is running, and everything unfreezes when the NSTimer reaches his time interval. For example: NSTimer is first fired up --> Application frozen --> 1 ... 2... 3... 4... 5... --> Application unfreezes, button is working. if I let the NSTimer do another run, it will freeze the application again for 5 secs. Thanks for helping. — itai alter

cheese cheese · Accepted Answer · 2010-04-18T10:19:12

"Note that from the perspective of NSRunloop, NSTimer objects are not "input"—they are a special type, and one of the things that means is that they do not cause the run loop to return when they fire." (from NSRunLoop Class Reference) - so I think you block the runloop from continuing? Perhaps put the timer to a different thread as solution? I have problems on this on my own, too :(

NSTimer freezes the app until it gets fired again?

1 Answers