iOS中设置禁止自动锁屏无效的解决方案

一般情况下，在代码中设置

    [UIApplication sharedApplication].idleTimerDisabled = NO;

这样可以禁止自动锁屏

然而从iOS 3 直到iOS10，禁止自动锁屏概率性失效的BUG苹果一直未修复

使用以下代码可完全禁止自动锁屏

-(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];
}