NSTimer scheduledTimerWithTimeInterval: repeats:NO selector method calls multiple times - iphone

Question

I am using NSThread along with NSTimer.
My code is like this
-(void) checkForRecentAlarm
{
if ([self.alarmThread isFinished])
{
[self.alarmThread cancel];
}
self.alarmThread = [[NSThread alloc] initWithTarget:self selector:#selector(startTimerForRecentAlarm) object:nil];
[self.alarmThread start];
//[NSThread detachNewThreadSelector:#selector(startTimerForRecentAlarm) toTarget:self withObject:nil];
}
-(void)startTimerForRecentAlarm
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init];
self.recentAlarmTime = [NSDate date];
self.dbObject = [[RADataBaseModelManager alloc] init];
self.recentAlarmTime = [self.dbObject getMostRecentAlarmTimeFromDB];
if (self.recentAlarmTime) {
NSTimeInterval timeIntervalToAlarm = [self.recentAlarmTime timeIntervalSinceNow];
NSRunLoop* runLoop = [NSRunLoop currentRunLoop];
//Fire timer every second to updated countdown and date/time
self.RATimer = [NSTimer scheduledTimerWithTimeInterval:timeIntervalToAlarm target:self selector:#selector(timerFireMethod:) userInfo:nil repeats:NO];
[runLoop run];
}
[pool release];
}
- (void)timerFireMethod:(NSTimer*)theTimer
{
[self.RATimer invalidate];
[theTimer invalidate];
self.RATimer = NULL;
theTimer = NULL;
[self playAlarm];
UIAlertView *alarmAlert = [[UIAlertView alloc] initWithTitle:#"Alarm" message:#"" delegate:self cancelButtonTitle:#"Close" otherButtonTitles:#"Snooze", nil];
[alarmAlert show];
[alarmAlert release];
alarmAlert = nil;
}
Now the problem is, my alertbox comes twice for one call in the
startTimerForRecentAlarm
method. So that the alert comes consequently twice and my view get stuck.
What will be problem here?
I am trying to implement an alarm with multiple alarm option using a single NSTimer.
Please help.
When I debug this, I can find many simultaneous threads are running on same code(UIAlertView).

Answer 1

I can't see any obvious reason why that would be called twice, but it does seem like an overly complex way of doing what you need to do.
Have you thought about using local notifications?
If you don't want to do that, you could refactor your code so it works like this:
1. Add a new event
2. If there's no timer or the time to the event is shorter than the time on the timer, then set the timer for this event.
3. When a timer fires, check for the next event and set a timer for that event (if there is one).

Answer 2

This does seem really complex. My general observation is that if you get two timer firings it's because you have two timers for some reason.
If you have multiple threads doing UIAlertView, you have another problem, because you can only (reliably) do UI from the main thread.