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

- (IBAction)pauseResumeTimer:(id)sender {

    if (timerRunning == NO) {
        timerRunning = YES;

    [pauseTimerBtn setTitle:@"Resume" forState:UIControlStateNormal];
    NSString *stringVal = [NSString stringWithFormat:@"%@",timeTxt.text];
    stringVal = [stringVal stringByReplacingOccurrencesOfString:@":" withString:@"."];

    float tempFloatVal = [stringVal floatValue];
    int minuteValue = floorf(tempFloatVal);
    float tempSecVal = [stringVal floatValue] - floorf(tempFloatVal);
    int secondVal = tempSecVal*100;
    minuteValue = minuteValue*60;

    oldTimeValue = minuteValue + secondVal;
    [timer invalidate];
    timer = nil;
}
else
{
    timerRunning = NO;
    [pauseTimerBtn setTitle:@"Pause" forState:UIControlStateNormal];
    startDate = [NSDate date];
    timer = [NSTimer scheduledTimerWithTimeInterval:0.25 target:self selector:@selector(timer:) userInfo:nil repeats:YES];
    }    
}

- (void)runTimer:(NSTimer *)timer {
    NSInteger secondsAtStart = (NSInteger)[[NSDate date] timeIntervalSinceDate:startDate];
    secondsAtStart = secondsAtStart + oldTimeValue;
    NSInteger seconds = secondsAtStart % 60;
    NSInteger minutes = (secondsAtStart / 60) % 60;
    NSInteger hours = secondsAtStart / (60 * 60);
    NSString *result = nil;
    result = [NSString stringWithFormat:@"%02ld:%02ld",(long)minutes,(long)seconds];
    timeTxt.text   =  result;

}