Thankfully, this question was posted 5 years ago, and Xcode has made leaps and bounds of progress since then.
However... this bug is still alive and kicking in 2015, using Xcode 6.2 and iOS 8.2.
Here's what you actually need to do, to prevent your device from going to sleep.
(Grab a beer, this is painful.)
When my app was first run on a device, it would load a bunch of data from a web service. However, if it took too long to run, the screen would fade, then turn off, the device would lock, and my web request would terminate with an ugly "The network connection was lost" error.
I attempted to add the code to simply set/unset the idleTimerDisabled
value, but this change didn't last very long, and the device would still auto-lock after a while.
// This didn't work for me (for very long !)
[UIApplication sharedApplication].idleTimerDisabled = NO;
[UIApplication sharedApplication].idleTimerDisabled = YES;
Instead, what I needed to do (depressed sigh..) was to have a timer set/unset this value every 20 seconds.
In my .h file:
@property (strong, nonatomic) NSTimer* stayAliveTimer;
-(void)callEveryTwentySeconds;
In my .m file:
-(void)callEveryTwentySeconds
{
// DON'T let the device go to sleep during our sync
[[UIApplication sharedApplication] setIdleTimerDisabled:NO];
[[UIApplication sharedApplication] setIdleTimerDisabled:YES];
}
-(void)loadDataFromWebService
{
self.stayAliveTimer = [NSTimer scheduledTimerWithTimeInterval:20.0
target:self
selector:@selector(callEveryTwentySeconds)
userInfo:nil
repeats:YES];
//
// Code to call our web service in a background thread and wait
// for it to finish (which might take a few minutes)
//
// Kill off our "Stay alive" timer, and allow the device to Auto Lock whenever it wants.
[self.stayAliveTimer invalidate];
// Give our device permission to Auto-Lock when it wants to again.
[[UIApplication sharedApplication] setIdleTimerDisabled:NO];
}
Really, Apple ?
It's 2015, and Xcode is really still this bad...?
I hope this code helps other Xcode victims.