NSTimer Not Stopping When Invalidated

Question

I have the following code in my .h file:

#import <UIKit/UIKit.h>
#import <CoreLocation/CoreLocation.h>
#import <AVFoundation/AVFoundation.h>
#import <MapKit/MapKit.h>

@interface LandingController : UIViewController<CLLocationManagerDelegate> {
    CLLocationManager *LocationManager;
    AVAudioPlayer *audioPlayer;

}

@property (nonatomic, retain) NSTimer *messageTimer;

- (IBAction)LoginButton:(id)sender;

@end

I have the following code in my .m file:

@interface LandingController ()

@end

@implementation LandingController
@synthesize messageTimer;

- (void)checkForMessages
{

    UIAlertView *alert = [[UIAlertView alloc]
                          initWithTitle:@"BINGO:"
                          message:@"Bingo This Works"
                          delegate:nil
                          cancelButtonTitle:@"Okay"
                          otherButtonTitles:nil];

    [alert show];

}

- (IBAction)LoginButton:(id)sender {

    if ([UserType isEqualToString:@"Owner"]) {

        if (messageTimer){ 
        [self.messageTimer invalidate];
        self.messageTimer = nil;
        }

    } else {

        if (!messageTimer){

           self.messageTimer = [NSTimer scheduledTimerWithTimeInterval:10.0
                                                             target:self
                                    selector:@selector(checkForMessages)
                                                           userInfo:nil
                                                            repeats:YES];


        }
    }

}

@end

But my timer doesn't want to stop when I call the invalidate.

The LoginButton is only pressed twice, once when the strResult is = to "Guard" and then the application changes it to be equal to "Owner" and the user presses the login button again, so I don't think I'm setting multiple timers.

After pressing the login button and starting the timer I segue to another view and then segue back to press the login button once more which is when I want the timer to stop. Do I need to do anything special to get the messageTimer since I switched views for a moment and then came back?

Any ideas?

Thanks!

Answer 1

You need to call [self.messageTimer invalidate] on the same thread on which you created the timer. Just make sure that the timer is created and invalidated on main thread.

dispatch_async(dispatch_get_main_queue(), ^{
    if ([UserType isEqualToString:@"Owner"]) {
        [self.messageTimer invalidate];
        self.messageTimer = nil;
    } else {
        self.messageTimer = [NSTimer scheduledTimerWithTimeInterval:10.0
                                                             target:self
                                                           selector:@selector(checkForMessages)
                                                           userInfo:nil
                                                            repeats:YES];
    }
});