self.timerProgress=[NSTimer scheduledTimerWithTimeInterval:50.0 target:self selector:#selector(stopProgressView) userInfo:nil repeats:NO];
-(void)stopProgressView
{
if ([self.timerProgress isValid]) {
[self.timerProgress invalidate];
self.timerProgress=nil;
}
}
and on a button click when i tried to invalidate NSTimer object
-(void)cancelTimer
{
if ([self.timerProgress isValid]) {
[self.timerProgress invalidate];
self.timerProgress=nil;
}
}
it don't get invalidate. It calls once stopProgressView after the interval of 50.
How to get resolve from this issue?
- (IBAction)stopTimer {
if ([timerProgress isValid]) {
[timerProgress invalidate];
}
}
Don't use self.timerProgress use just timerProgress
The most likely reason for this is that your timer scheduled on a different run loop to the one where you try and invalidate it.
Timers must be invalidated on the same thread/runloop as the run loop that they are scheduled on.
Cocoa touch isn't thread safe, so you should be running all UI related activities on the main thread. It may work if you do GUI work on different threads, but then you'll get random crashes, and you'll also generate timer problems like this.
It seems like from what you're posting it should work. This is how I have it in my apps and it works fine.
However, you could try making the selector one that takes a timer object like:
-(void)stopProgressView:(NSTimer *)timer{
//do stuff with timer here
}
Note that this would also mean that you should change #selector(stopProgressView) to #selector(stopProgressView:). Although for the record my current stop timer function just uses [self.timer invalidate] and it works fine.
My other piece of advice for debugging is to use NSLogs to make sure each of the methods are in fact getting called, and that when the method is called an NSLog within the if clause to make sure that works.
You create NSTimer with out NSRunLoop so your NSTimer not started, to add this code after
self.timerProgress = [NSTimer scheduledTimerWithTimeInterval:50.0
target:self
selector:#selector(stopProgressView)
userInfo:nil
repeats:NO];
//add
[[NSRunLoop currentRunLoop] addTimer:_tapTimer
forMode:NSDefaultRunLoopMode];
Related
So I've got a timer that is not repetitive. Each time it fires, the method that being executed decide if to reschedule it or not according to some inner logic of my app.
This method is available from other parts of the app, so the first thing that I'm doing in the method is to check if the timer is still valid (to know if the initiator was the timer or a different entity) so in case it wasn't initiated by the timer I want to invalidate it:
if (self.pollingTimer.isValid) {
[self.pollingTimer invalidate];
self.pollingTimer = nil;
}
I've noticed that if the method is being called due to the timer being fired - I always receive a true value from the isValid property, even though when looking at the NSTimer documentations under the scheduledTimerWithTimeInterval:(NSTimeInterval)seconds target:(id)target selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)repeats method:
repeats
If YES, the timer will repeatedly reschedule itself until invalidated. If NO, the timer will be invalidated after it fires.
Discussion
After seconds seconds have elapsed, the timer fires,
sending the message aSelector to target.
I'm having hard time to understand when the timer is being automatically invalidated which bring me to my questions:
Any idea why I always get YES from isValid?
What is the exact definition of the timer fires? Is it just sending the message aSelector to target as stated in the documentation? or is it finishing the execution of the method? (which might explain what I'm experiencing)
Thanks in advance.
A timer is not a real-time mechanism; it fires only when one of the run loop modes to which the timer has been added is running and able to check if the timer’s firing time has passed. Therefore, the timer does not immediately invalidate itself, but at the end of the run loop.
As a simple test, you can see:
- (void)viewDidLoad {
[super viewDidLoad];
_timer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:#selector(timerFired) userInfo:nil repeats:NO];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
if (self.timer.isValid){
NSLog(#"--> TIMER VALID");
} else {
NSLog(#"TIMER INVALID!");
}
});
}
- (void) timerFired {
if (self.timer.isValid){
NSLog(#"--> TIMER VALID");
} else {
NSLog(#"TIMER INVALID!");
}
}
This will log --> TIMER VALID from the timerFired method and when the block from dispatch_after is called, you will see TIMER INVALID!. So, when you schedule a timer with repeats:NO, it is guaranteed to not reschedule itself but it will not invalidate immediately.
So, to answer your question:
repeats
If YES, the timer will repeatedly reschedule itself until
invalidated. If NO, the timer will be invalidated after it fires (but not immediately)
I made a test like this:
self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(xx) userInfo:nil repeats:NO];
- (void)xx
{
if ([self.timer isValid]) {
NSLog(#"isvalid");
}
dispatch_async(dispatch_get_main_queue(), ^{
if ([self.timer isValid]) {
NSLog(#"isvalid");
}else{
NSLog(#"isInvalid");
}
});
static int i = 0;
NSLog(#"%d",i++);
}
and the result is:
isvalid
0
isInvalid
thus, I guess when timer is fired,the function is execute like this:
void __NSFireTimer(){
id yourObj;
[yourObj performSelector:#selector(yourSelector)];
timer.isvalid = NO;
}
what you believe is:
void __NSFireTimer(){
id yourObj;
timer.isvalid = NO;
[yourObj performSelector:#selector(yourSelector)];
}
So, just accept it.You can put your check valid code in dispatch_asyn() ,like the test code.
This is how I used my timers. First initialise it on the top as
#property (strong, nonatomic) NSTimer *refreshTimer;
then this two methods, to create and invalidate the timer. "Its very important to invalidate the current timer if you want to create another timer with same name" otherwise their will be two timers.
- (void)startTimer {
if (_refreshTimer) {
[self invalidateTimer];
}
_refreshTimer = [NSTimer scheduledTimerWithTimeInterval:15.0
target:self
selector:#selector(determineIfPartOfgroup)
userInfo:nil
repeats:YES];
}
- (void)invalidateTimer {
if (_refreshTimer) {
[_refreshTimer invalidate];
_refreshTimer = nil;
}
}
I hope this will help you.
I use this code for stopping NSTimer
[timer invalidate]
timer = nil;
It works fine for the first run. But, after I resume the timer with this code.
timer = [NSTimer scheduledTimerWithTimeInterval:5.0
target:self
selector:#selector(checkNewUpdates)
userInfo:nil
repeats:YES];
NSTimer won't stop anymore with [timer invalidate]
It look like multiple instance of timer is running simultaneously. You can do one thing, before start to run a new timer, check for previous instance of timer, and if timer instance is available, then invalidate it. After this start new instance
if(timer)
{
[timer invalidate];
timer = nil;
}
timer = [NSTimer scheduledTimerWithTimeInterval:5.0
target:self
selector:#selector(checkNewUpdates)
userInfo:nil
repeats:YES];
In apple's official document they said:
You must send this message from the thread on which the timer was
installed. If you send this message from another thread, the input
source associated with the timer may not be removed from its run loop,
which could prevent the thread from exiting properly.
If your timer is running on main thread, do this:
[timer performSelectorOnMainThread:#selector(invalidate) withObject:nil waitUntilDone:YES];
If it is on any other thread, lets call the thread myThread, then do this:
[timer performSelector:#selector(invalidate) onThread:myThread withObject:nil waitUntilDone:NO];
Hope this helps.. :)
Just invalidate the timer inside the selector that fires. That will ensure you have a pointer to the correct timer (which is probably why your invalidate call isn't working:
timer = [NSTimer scheduledTimerWithTimeInterval:5.0
target:self
selector:#selector(checkNewUpdates:)
userInfo:nil
repeats:YES];
Note the colon after checkNewUpdates:
Then, in your checkNewUpdates: method, do something like this:
- (void)checkNewUpdates:(NSTimer*)timer
{
// do somehting
// Then, check if the criteria for stopping the timer has been met, and invalidate it here.
if( self.shouldStopTimer ) // made up variable, use your own criteria.
{
[timer invalidate];
}
}
I know this doesnt answer your question per-se;
Can I suggest using polling mechanism instead of a timer? Ive had a world of trouble with NSTimers in the past and polling was a good alternative. Ive made a simple one below.
- (void) doPoll {
// do logic here
if (shoudStop) {
return;
}
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, X * NSEC_PER_SEC)),
dispatch_get_main_queue(), ^{
[self doPoll];
});
}
This is just a simple example, it does not stop retain cycles If you choose to try this, Yours should.
Hope it helps.
I've opted in to background location updates in an App I'm working on.
In my LocationManager class, I've got a method that looks like this:
- (void)beginUpdateTimer
{
[self.updateTimer invalidate];
self.updateTimer = [NSTimer timerWithTimeInterval:ForceUpdateDuration
target:self
selector:#selector(updateWithLastKnownLocation)
userInfo:nil
repeats:NO];
NSRunLoop *runloop = [NSRunLoop currentRunLoop];
[runloop addTimer:_updateTimer forMode:NSRunLoopCommonModes];
}
The method -updateWithLastKnownLocation potentially calls beginUpdateTimer again.
In testing my app, I've discovered that the timer continues to fire upon the app moving in to the background, so long as I've enabled background location updates. Shouldn't this NOT be happening though? Can I rely on this?
Thanks!
Yes, you can rely on it, provided the timer was running at the time you went into the background.
[self performSelectorInBackground:#selector(method) withObject:nil];
-(void)method
{
timer1 = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(getLastImageName1) userInfo:nil repeats:YES];
runLoop = [NSRunLoop currentRunLoop];
[runLoop addTimer:timer1 forMode:NSRunLoopCommonModes];
[runLoop run];
}
-(void)viewdidunload
{
[timer1 invalidate];
timer1=nil;
}
I start Timer in HomeViewController even I invalidate, it keeps running in OtherViewController. What is wrong with my code?
First of all, when you're overriding life cycle methods, you should include a call to the super version of that method.
Second of all, Objective-C is case sensitive, so even if your app would try to call the life-cycle even, viewDidUnload, your method would simply never be called because that's what you titled your method.
Third of all, viewDidUnload was deprecated in iOS 6.0 and shouldn't be used at all by this point unless you're going way out of your way to support backward compatibility. It will never be called in iOS 6.0 and greater.
If you want the timer to stop when the user navigates away from the current view, you'll want something like this:
- (void)viewDidDisappear:(BOOL)animated {
[super viewDidDisappear:animated];
if (timer1.isValid) {
[timer1 invalidate];
}
timer1 = nil;
}
If you're looking for something else, you'll need to elaborate on what it is you want to accomplish exactly.
If you ARE working on a pre-iOS 6.0 project, for whatever reason, the reason your method isn't being called is at least in part because it is spelled wrong. Again, Objective-C is case sensitive. Your method name should be spelled viewDidUnload.
For future reference, the question shouldn't really be "why isn't my timer invalidating?" You should have start by using breakpoints or NSLog statements to determine whether or not your method, viewdidunload, which tries to invalidate the timer even fires. When you find out it's not being called, do a search to ask "How come viewdidunload isn't called?" Then you'll go fix the capitalization problem and the problem will (probably) remain, so do some more research. And if at the end, you still can't figure it out, as a worst case scenario, the post question should be "how come viewdidunload isn't called?"
timer1 = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(getLastImageName1:) userInfo:nil repeats:YES];
set colon for function in selector
-(void) getLastImageName1 :(NSTimer*)timer1
{
//Do your all process and invalidate after completion
[timer1 invalidate];
}
or if you want to remove timer after moving to next view controller use how #nhgrif mentioned
- (void)viewDidDisappear:(BOOL)animated
{
[timer1 invalidate];
}
[self performSelector:#selector(method) withObject:nil afterDelay:0.0];
-(void)method
{
timer1 = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(getLastImageName1) userInfo:nil repeats:YES];
runLoop = [NSRunLoop currentRunLoop];
[runLoop addTimer:timer1 forMode:NSRunLoopCommonModes];
[runLoop run];
}
- (void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];
[timer1 invalidate];
timer1=nil;
}
There is no need to add the timer (again) on the main run loop. Or is it necessary for You to run it also in commonModes? For me it was never necessary.
From the NSTimer Documentation:
scheduledTimerWithTimeInterval:invocation:repeats:
Creates and returns a new NSTimer object and schedules it on the
current run loop in the default mode.
Since the NSRunLoop Documentation points out that you can add timer on several run loop modes, maybe this is the problem.
addTimer:forMode:
Discussion You can add a timer to multiple input modes. While running
in the designated mode, the receiver causes the timer to fire on or
after its scheduled fire date. Upon firing, the timer invokes its
associated handler routine, which is a selector on a designated
object.
Also I don't get why you are invoking the timer creation with performSelector?
I just wrote a minimalistic sample. thats totally working!
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:#selector(doWork:) userInfo:Nil repeats:YES];
}
- (void)viewDidDisappear:(BOOL)animated{
[self.timer invalidate];
[super viewDidDisappear:animated];
}
- (void) doWork:(id) userInfo
{
NSLog(#"Working again");
}
Hope this helps.
-(void)viewDidUnload is a delegate which fires on memory warning only and is deprecated after iOS 6. It will also never fire on the simulator.
Stop timer in
- (void)viewWillDisappear:(BOOL)animated
or in
- (void)viewDidDisappear:(BOOL)animated
I have a real weird behavior of NSTimer object.
I'm trying to call ChangePic method with repeat counts of 2 seconds, But the timer isn't repeating. and i have this problem only in 1 class in the project
I have 5 View Controllers in my App, and the same code works in all classes except this one.
Does anybody has idea how could it be? is it possible that something blocking the timer ?
-BTW, ChangePic Method is called only once, and not repeating.
My Code:
ViewController.h
#property (nonatomic, strong) NSTimer *timer;
ViewController.m
_timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:#selector(ChangePic) userInfo:nil repeats:YES];
[_timer fire];
-(void) ChangePic {
NSLog(#"testing");
}
Assign it to the property not the backing variable.
self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:#selector(ChangePic) userInfo:nil repeats:YES];
It's difficult to say exactly what your issue is given that there isn't a whole lot of background given. I can tell you that I answered another question where the problem turned out to be the fact that one of the views was blocking the timer. Timers can run on a number of different modes and different scenarios can cause the timer to sometimes be blocked. Try adding the timer to all common modes like this:
[[NSRunLoop currentRunLoop] addTimer:_timer forMode:NSRunLoopCommonModes];
Also, like #Hejazi said, remove the 'fire' method call. It's not needed on a scheduled timer.