calling a method after each 60 seconds in iPhone

Use NSTimer

NSTimer* myTimer = [NSTimer scheduledTimerWithTimeInterval: 60.0 target: self
                                   selector: @selector(callAfterSixtySecond:) userInfo: nil repeats: YES];

After each 60.0 second , iOS will call the below function

-(void) callAfterSixtySecond:(NSTimer*) t 
{
    NSLog(@"red");
}