how to pause and resume NSTimer in iphone

Question

hello I am developing small gameApp. I need to pause the timer,when user goes to another view [say settings view]. when user comes back to that view , I need to resume the

Answer 1

on Start - 
startNewCapture = [NSDate date];

on Pause - 
captureSessionPauseDate = [NSDate date]; 
captureSessionTimeInterval = [captureSessionPauseDate timeIntervalSinceDate:startNewCapture];

on Resume - 
NSDate *dateNow = [NSDate date];
startNewCapture = [NSDate dateWithTimeInterval:-captureSessionTimeInterval sinceDate:dateNow];