iPhone - phone goes to sleep even if idleTimerDisabled is YES

I set and un-set this property throughout my app using:

[UIApplication sharedApplication].idleTimerDisabled = YES;

Setting this where you're having trouble could fix it, though it might be a bit of a band-aid solution.

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.

try to use

[UIApplication sharedApplication].idleTimerDisabled = NO;
[UIApplication sharedApplication].idleTimerDisabled = YES;

instead of

[UIApplication sharedApplication].idleTimerDisabled = YES;

funny hack but it works

see also the thread idleTimerDisabled not working since iPhone 3.0