Question

What is a good way to record time between user events on iPhone? ie. time between pressing Button_A and Button_B.

Answer 1

A more accurate way than using [NSDate date] is to use the timestamp property of the UIEvent. To get the UIEvent, make sure you use the two-argument form for the target-action method.

- (IBAction)buttonPressed:(UIButton *)sender event:(UIEvent *)event
{
    NSTimeInterval timestamp = event.timestamp;
    NSTimeInterval secondsSinceLastEvent = timestamp - lastTimestamp;
}