Changing a uilabel text at different time intervals - iphone

Question

I am building a simple fitness/training app for iPhone. The user can pick a type of training session from a table which takes them to a view controller which contains a stopwatch. This view has labels populated from a mutable array.
I can get the stopwatch to work and the initial labels to populate from the array, but cannot work out how to get the labels to change at set time intervals. These intervals won't be regular so might be at 10mins, then 25, then 45 etc. I have been trying to do this via If statements where the timer == 25, for example. I'm sure this is a basic solution but I'm new to programming and can't work it out.
Timer code as follows:
- (void)updateTimer
{
NSDate *currentDate = [NSDate date];
NSTimeInterval timeInterval = [currentDate timeIntervalSinceDate:startDate];
NSDate *timerDate = [NSDate dateWithTimeIntervalSince1970:timeInterval];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"HH:mm:ss.S"];
[dateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0.0]];
NSString *timeString=[dateFormatter stringFromDate:timerDate];
timerLabel.text = timeString;
}
Start timer:
- (IBAction)startTimerButton:(id)sender {
if (timer == nil) {
startDate = [NSDate date];
// Create the stop watch timer that fires every 0.1s
timer = [NSTimer scheduledTimerWithTimeInterval:1.0/10
target:self
selector:#selector(updateTimer)
userInfo:nil
repeats:YES];
}
else {
return;
}
}

Answer 1

I'm not too sure what you're after. If you set the time interval to be 10 minutes/25 minutes etc. instead of 1.0/10 then in your time fired code you will know what the time interval for the timer is.
You can always query the time interval using the timeInterval instance method. Perhaps as follows.
- (void)updateTimer:(NSTimer*)timer
{
if ([timer timeInterval] == 10 * 60) // 10 minutes have elapsed
{
// Do something for this timer.
}
else if ([timer timeInterval] == 20 * 60) // 20 minutes have elapsed
{
}
}
Notice that I've added the timer as an argument to your updateTimer function. You would then have to use the #selector(update:) (with the colon at the end!) selector in your scheduledTimerWithTimeInterval method. When your callback selector gets called, it will then have passed to it the timer.
Or if you have a pointer to the timer you created in your 'startTimerButton' you could use that as follows:
- (void)updateTimer:(NSTimer*)timer
{
if (timer == myTenMinuteTimer) // 10 minutes have elapsed
{
// Do something for this timer.
}
else if (timer == myTwentyMinuteTimer) // 20 minutes have elapsed
{
}
}
Notice that in the second cause you're comparing the pointer to two objects and using that, where as in the first your comparing the value of a method for two objects, so the objects don't have to necessarily be a pointer to the same object in order to be evaluated to be true.
Hope this helps!