How to get yourself an interval of time...

C4WorkSpace.m

//
//  C4WorkSpace.m
//  timeInterval
//
//  Created by moi on 12-09-30.
//  Copyright (c) 2012 moi. All rights reserved.
//

#import "C4WorkSpace.h"

@implementation C4WorkSpace {
    NSDate *start, *end;
}

-(void)touchesBegan {
    start = [NSDate dateWithTimeIntervalSinceNow:0];
}

-(void)touchesEnded {
    end = [NSDate dateWithTimeIntervalSinceNow:0];
    CGFloat interval = [end timeIntervalSinceDate:start];
    C4Log(@"You touched the screen for %4.2f seconds",interval);
}

@end