Time elapsed button in the iphone sdk - iphone

Question

How do you create a time elapsed button in objective-c iphone SDK. To be a little more specific, this button will show in text how much time has elapsed since you've been holding the button. So for the time to elapse you must still have a finger on the button, not letting go. Once you let go the timer should restart. Note: For the iphone, not mac.

Answer 1

Use these two methods for buttons events. touchDown is called when you press the button and touchUp will be called when you lift your finger from the button. Calculate the time difference between these two methods. Also you can start timer in touchDown and stop/restart it in touchUp.
//connect this action with Touch up inside
- (IBAction)touchUp:(id)sender {
NSLog(#"up");
}
//connect this to tocuh down
- (IBAction)touchDown:(id)sender{
NSLog(#"down");
}

Answer 2

first, set an int variable at your header file
#property int timerCount;
#property (nonatomic, strong)NSTimer *yourTimer;
dont forget to synthesize it at the implementation file
(if you're still on lower SDK, you can change "strong" to "retain")
and then make the button and it's function
UIButton *yourButton = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];
[yourButton setTag:1];
[yourButton setBackgroundColor:[UIColor redColor]];
[yourButton addTarget:self action:#selector(buttonHoldDown) forControlEvents:UIControlEventTouchDown];
[yourButton addTarget:self action:#selector(buttonRelease) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:yourButton];
this way, you've add a button at x:0 y:0 on your view with red color, containing two action target which is touch down and up inside
when you touch the button, the buttonHoldDown function is triggered, and when u release the button, the buttonRelease function is triggered
and then, fill the function
-(void)buttonHoldDown
{
yourTimer = [NSTimer timerWithTimeInterval:1 target:self selector:#selector(timerStart) userInfo:nil repeats:NO];
timerCount = 0;
}
-(void)buttonHoldUp
{
NSLog(#"the timer stops at %d seconds", timerCount);
timerCount = 0;
[yourTimer invalidate];
}
-(void)timerStart
{
timerCount++;
}
this way, when you touch the button, the program creates a timer and revalue the int timerCount to 0, which will be increased as the timer ticks in the "timerStart" function.
as you release the button, the function will track your current timerCount record and print it on the system, and then stop the timer