How to stop NSTimer

Question

Hey so i am just making an example application and i am having a little trouble, So i have a table view and then i have a few rows and when a user clicks a row it takes them

Answer 1

You Could Use Two Different Things

    [timername invalidate];

Or You Could Use

    timername = nil;

Answer 2

like this:

[yourtimername invalidate];

But be careful, you cant stop the timer if it's already stopped because your app will crash.

Answer 3

Use the below code. It will work But keep in mind that it must only be called if our timer is in running mode else the application will get crashed.

- (void)viewWillDisappear:(BOOL)animated {
    //BEFORE DOING SO CHECK THAT TIMER MUST NOT BE ALREADY INVALIDATED
    //Always nil your timer after invalidating so that 
    //it does not cause crash due to duplicate invalidate
       if(timer)
       {
         [timer invalidate];
         timer = nil;
       }
    [super viewWillDisappear:animated];
}

Answer 4

Trick is to use a singleton class, google myGlobals class which is mostly used as a singleton Although if u do wish to use NSTimer, then

lets say the view 1 is which u go into and view 2 is the one which u go back 2.

So in case of view 2, write the NSTimer to invalidate the timer in the viewDidLoad(Assuming you have two separate classes for both views).Problem will occur because when u go to view 1, the view 2 Timers will be dealloc. So, make a Singleton class and save the NSTimer pointer like this

//to be done in viewDidLoad function
theGlobals *globals = [theGlobals alloc] init];// for the singleton class to initiate,
[globals.myTimer invalidate];


//to be done in viewDidUnload
theGlobals *globals = [theGlobals alloc] init];// for the singleton class to initiate,
globals.myTimer = [NSTimer scheduledTimerWithTimeInterval: 5.0
                                                 target: self
                                               selector:@selector(onTick)
                                               userInfo: nil repeats:YES];

oh , and here is the myGlobals class code that u will need

//theglobals.h file

#import <Foundation/Foundation.h>


@interface theGlobals : NSObject 
{
    NSTimer *myTimer;
}

@property (nonatomic, copy) NSString *changeyes;



+(theGlobals*)sharedInstance;
@end

//implementaton .m file

#import "theGlobals.h"
@implementation theGlobals

@synthesize myTimer;



static theGlobals *sharedInstance;

- (id) init
{
return self;
}

+(theGlobals*)sharedInstance
{
if (!sharedInstance)
{
    sharedInstance = [[theGlobals alloc] init];
}
return sharedInstance;
}
@end

Answer 5

Just invalidate the timer

[timer invalidate];

Answer 6

As iCoder says it has to be invalidated in viewWillDisappear.

I added the following just to make sure. it works for me. Hope it helps (and adds to icoders answer do not intent to copy)

- (void) startTimer
{
[self stopTimer];
timer = [NSTimer scheduledTimerWithTimeInterval: 5.0
                                                     target: self
                                                   selector:@selector(onTick)
                                                   userInfo: nil repeats:YES];

}

- (void) stopTimer
{
    if (timer) {
        [timer invalidate];
        timer = nil;
    }

}