NSTimer fails to invoke methord

Following is my sample code.

@interface TrackTimer : NSObject {

    NSTimer *timer;
}

@property (nonatomic, retain) NSTimer *t开发者_运维知识库imer;

- (void) startTimer;
- (void) stopTimer;
- (void) timerFired;

@end


TrackTimer.m

@synthesize timer;

- (void) startTimer
{

NSLog(@"Timer started ...");

if(timer)
{
    timer = nil;    
}
timer = [NSTimer scheduledTimerWithTimeInterval:30.0 target:self selector:@selector(timerFired) userInfo:nil repeats:NO];

}

- (void) stopTimer
{

NSLog(@"Timer stoped ...");
[tTimer invalidate];

}


- (void) timerFired
{

   NSLog(@"Timer Fired ... :)");    
}

I have to use the same timer object from 3 different view controllers, my problem is startTimer method do not invoke timerFired method in 2nd UIViewController. Its works perfectly on 1st and 3rd View Controller.

appln Flow : 1stView -> 2ndView -> 3rdView

You are doing everything right... almost. Your timer does not fire, because of the "if" statement.

if (timer) {
    timer = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector:@selector(boom) userInfo:nil repeats:NO];
}

Here, the "if" statement returns NO, because the timer is not yet initialized.. The fact that you make it a property and synthesize it does not mean that (timer != nil)

If you remove the "if" statement it should work...

From the Apple docs on NSTimer:

The message to send to target when the timer fires. The selector must have the following signature:
- (void)timerFireMethod:(NSTimer*)theTimer

So, it looks like the signature of your timerFired method needs to be expanded to include one parameter '(NSTimer*)theTimer' and your selector needs to be @selector(timerFired:)

Don't really know how you do that, but NStimer has a class method called + (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)seconds target:(id)target selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)repeats. So you can do it like this:

 timer=[NSTimer scheduledTimerWithTimeInterval:2 target:self 
                                               selector:@selector(timerFired)
                                               userInfo:nil
                                                repeats:YES];

This will invoke the timerFired method for you.

P.S.Here's the link to a simple app that does just what you want.

http://www.mediafire.com/?8uz115drqzb2nan