Detecting user inactivity/idle time since last touch on screen

Recently I required to find inactivity of screen in one of my iPad project.  Here is the steps by which I completed this task.

Step 1 –  Add a class (IdleTimeCheck) in your project which subclass UIApplication. In the implementation file, override the sendEvent: method like so:

- (void)sendEvent:(UIEvent *)event {
[super sendEvent:event];

// Only want to reset the timer on a Began touch or an Ended touch, to reduce the number of timer resets.
NSSet *allTouches = [event allTouches];
if ([allTouches count] > 0) {
// allTouches count only ever seems to be 1, so anyObject works here.
UITouchPhase phase = ((UITouch *)[allTouches anyObject]).phase;
if (phase == UITouchPhaseBegan || phase == UITouchPhaseEnded)
[self resetIdleTimer];

- (void)resetIdleTimer {
if (idleTimer) {
[idleTimer invalidate];
[idleTimer release];

idleTimer = [[NSTimer scheduledTimerWithTimeInterval:maxIdleTime target:self selector:@selector(idleTimerExceeded) userInfo:nil repeats:NO] retain];

- (void)idleTimerExceeded {
NSLog(@"idle time exceeded");

where maxIdleTime and idleTimer are instance variables.

Step 2 – Modify your UIApplicationMain function in main.m file to use your UIApplication subclass class as principal class.

int retVal = UIApplicationMain(argc, argv, @"IdleTimeCheck",nil);

And its done.

Hope it help someone who is looking for something like this.