In ios5.0 with ARC, in my rootviewcontroller I call a method in a security manager object that is held by the app delegate. In that method I setup the timer as below
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:5.0 target:self
selector:#selector(updateModel:) userInfo:str repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
However, this never fires the selector ie. updateModel: never gets called. What may be wrong? Is there another more efficient way I can do this without using NStimer?
Could also be a threading problem:
if
[NSThread isMainThread]
is false then start the timer like this:
dispatch_async(dispatch_get_main_queue(), ^{
timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(tick:) userInfo:nil repeats:YES];
})
You seem to be a bit mixed up with your timer variable.
You initialize a new timer but you aren't actually using it. Do you want to use the timer you initialized or do you want to you ApplicationDelegate.timer?
Here are the two possible solutions.
Option One (assuming that you have a class instance titled ApplicationDelegate and that it has a timer property):
ApplicationDelegate.timer = [NSTimer scheduledTimerWithTimeInterval:5.0 target:self selector:#selector(updateModel:) userInfo:str repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:ApplicationDelegate.timer forMode:NSRunLoopCommonModes];
Option Two:
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:5.0 target:self selector:#selector(updateModel:) userInfo:str repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
I catch the same issue and I fire timer in main queue to solve it:
[NSURLConnection sendAsynchronousRequest:request queue:_operationQueue
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error){
[self loopUpUpdateStart];
}];
-(void)loopUpUpdateStart{
dispatch_async(dispatch_get_main_queue(), ^{
_loopTimerForUpRevision =
NSTimer scheduledTimerWithTimeInterval: kNetworkLoopIntervalUpRev
target: self
selector: #selector(myCoolMethod)
userInfo: nil
repeats: YES];
TRACE(#"Start Up updates");
});
}
This line has several problems:
[[NSRunLoop currentRunLoop] addTimer:ApplicationDelegate.timer forMode:NSRunLoopCommonModes];
First, it should not be required at all. -scheduledTimerWithTimeInterval:... already adds the timer to the runloop. You do not need to add it again.
Second, the local variable timer is unrelated to the property ApplicationDelegate.timer (which is presumably nil at this point).
If you're talking to the application delegate so much that you've created something called ApplicationDelegate (a global? a macro?), you're talking to it too much. The application delegate is the delegate for the application; it assists in the application starting and stopping and responding to system events. The application delegate is not a place to store global variables. A timer is definitely not the kind of thing you'd fetch from another object in any case.
Related
I want to run a selector using NSTimer which contains some network calls and some other tasks. I want to do that on global queue.
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSTimer * myTimer=[[NSTimer alloc]init];
myTimer = [NSTimer timerWithTimeInterval:10*60 target:self selector:#selector(syncGroupAutomatically) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:myTimer forMode:NSRunLoopCommonModes];
[[NSRunLoop currentRunLoop] run];
});
-(void)syncGroupAutomatically
{
NSLog(#"Some Network calls and some other things\n");
}
If I run this code, it works fine when app is in foreground, but as soon as I press the home button it stops calling the syncGroupAutomatically method.
If anybody having any idea how to run this NSTimer even when app is in the background. Please help me.
I am creating a game, and inside the game I need to get a time counter.
I works great but when I scroll the map it stops and then when I finish scrolling it start again. I fix this with dispatch_async. Here is the code
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(timeNext) userInfo:nil repeats:NO];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
[[NSRunLoop currentRunLoop] run];
});
Timer:
__block NSTimer *timer;
But if the app goes to the background I need to stop this times (and when it get active it starts again).
With this way I can scroll the map and the timer works well I try:
- (void)timeNext {
[timer invalidate];
}
and didin't work. Anyone knows how to stop it? or any other idea to accomplish this task?
Don't create your timer on a global queue's thread and then start a run loop on that thread.
Just create your timer on the main thread (main run loop), and add it to the tracking run loop mode. A timer can be added to multiple run loop modes.
timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(timeNext) userInfo:nil repeats:NO];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:UITrackingRunLoopMode];
If you're using UIScrollView to scroll via your game world, timer will be paused while scroll is tracking touches - you need to setup timer to use it with different mode - UITrackingRunLoopMode, e.g.
[[NSRunLoop currentRunLoop] addTimer:timer forMode:UITrackingRunLoopMode];
instead of
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
This will allow your timer to fire events while controls such as scroll is tracking user's touches.
[EDIT]
You create timer e.g. via
+ (NSTimer *)timerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)yesOrNo;
then add this timer to runloop (basically, you should add it to your app main runloop):
NSTimer* timer = [NSTimer timerWithTimeInterval:1./60. target:self selector:#selector(tick) userInfo:nil repeats:YES];
[[NSRunLoop mainRunLoop] addTimer:timer forMode:UITrackingRunLoopMode];
I use NSRunLoopCommonModes instead of UITrackingRunLoopMode, everythings looks fine. The main thread ui operation will not block tick function anymore.
NSTimer* timer = [NSTimer timerWithTimeInterval:1./60. target:self selector:#selector(tick) userInfo:nil repeats:YES];
[[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
I have an NSTimer
timer = [NSTimer scheduledTimerWithTimeInterval:1
target:self
selector:#selector(periodicTimer)
userInfo:nil
repeats:YES];
which does
- (void)periodicTimer
{
NSLog(#"Bang!");
if (timerStart != nil)
[timerLabel setText:[[NSDate date] timeDifference:timerStart]];
}
The problem is that while scrolling a tableview (or doing other tasks) the label doesn't get updated, furthermore, "Bang!" doesn't appear, so I supposed the method doesn't get called.
My question is how to update the label periodically even when the user is playing around with the app interface.
You'll need to add your timer to the UITrackingRunLoopMode to make sure your timer also fires during scrolling.
NSRunLoop *runloop = [NSRunLoop currentRunLoop];
NSTimer *timer = [NSTimer timerWithTimeInterval:0.1 target:self selector:#selector(myTimerAction:) userInfo:nil repeats:YES];
[runloop addTimer:timer forMode:NSRunLoopCommonModes];
[runloop addTimer:timer forMode:UITrackingRunLoopMode];
From:
https://stackoverflow.com/a/1997018/474896
Not sure about this one, but my first guess would be that the main thread on which the interface is being rendered your timer just doesn't get a chance to do anything while its updating the interface.
You could create a new thread with a new run loop for your timer, but that is a bit of an ugly solution maybe. What functionality in your app are you trying to achieve? Maybe we can advise a better strategy than using a timer.
I am wondering if someone can explain why dispatching back to the main queue and creating a repeating NSTimer I am having to add it to RUN LOOP for it too fire? Even when using performselectorOnMainThread I still have to add it to a RUN LOOP to get it to fire.
Below is an example of my question:
#define queue dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
#define mainqueue dispatch_get_main_queue()
- (void)someMethodBeginCalled
{
dispatch_async(queue, ^{
int x = 0;
dispatch_async(mainqueue, ^(void){
if([_delegate respondsToSelector:#selector(complete:)])
[_delegate complete:nil];
});
});
}
- (void)compelete:(id)object
{
[self startTimer];
//[self performSelectorOnMainThread:#selector(startTimer) withObject:nil waitUntilDone:NO];
}
- (void)startTimer
{
NSTimer timer = [NSTimer timerWithTimeInterval:3 target:self selector:#selector(callsomethingelse) userInfo:nil repeats:YES];
//NSDefaultRunLoopMode
[[NSRunLoop currentRunLoop] addTimer:_busTimer forMode:NSRunLoopCommonModes];
}
EDIT:
I believe I worded this question very poorly. I would like to know why [[NSRunLoop currentRunLoop] addTimer:_busTimer forMode:NSRunLoopCommonModes]; is necessary in startTimer if I call someMethodBeginCalled. If I don't include that line, the timer doesn't fire.
If I call startTimer from viewDidLoad for example, I can remove the NSRunLoop line and the timer will fire every 60 seconds.
And here's how to add an NSTimer to a runloop:
NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
[runLoop addTimer:timer forMode:NSDefaultRunLoopMode];
You could always use this method instead:
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:3 target:self selector:#selector(getBusLocation) userInfo:nil repeats:YES];
This will save you a line, as it will add it to the run loop automatically.
Because, as the docs say:
Timers work in conjunction with run loops. To use a timer effectively,
you should be aware of how run loops operate—see NSRunLoop and
Threading Programming Guide. Note in particular that run loops retain
their timers, so you can release a timer after you have added it to a
run loop.
It is a design decision that Apple made when they wrote the code for NSTimer (and I'm sure they had good reason to do so) and there is nothing we can do to get around it. Is it really that burdensome?
Like #sosborn said, NSTimers depend on NSRunLoops, and since GCD queues create threads that don't have run loops, NSTimer doesn't play well with GCD.
Check out this other StackOverflow question on the matter: Is it safe to schedule and invalidate NSTimers on a GCD serial queue?
To solve that problem, I implemented MSWeakTimer: https://github.com/mindsnacks/MSWeakTimer (and had the implementation checked by a libdispatch engineer at the last WWDC!)
Timer method won't be called since GCD queues create threads that don't have run loops
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
[NSTimer scheduledTimerWithTimeInterval:1 repeats:YES block:^(NSTimer * _Nonnull timer) {
NSLog(#"Timer method from GCD main queue");
}];
});
However when dispatched on main queue the timer method will be called as it will get added to main threads run loop.
dispatch_async(dispatch_get_main_queue(), ^{
[NSTimer scheduledTimerWithTimeInterval:1 repeats:YES block:^(NSTimer * _Nonnull timer) {
NSLog(#"Timer method from GCD main queue");
}];
});
Adding the timer to the runloop didn't work in my case. I had to create the timer on the main thread. I was doing this thread creation in a MultipeerConnectivity delegate.
dispatch_async(dispatch_get_main_queue(), ^{
self.timer = [NSTimer scheduledTimerWithTimeInterval:self.interval invocation: self.invocation repeats:YES];
});
My code is:
-(void) timerRun{...}
-(void) createTimer
{
NSTimer *timer;
timer = [NSTimer timerWithTimeInterval:1.0
target:self
selector:#selector(timerRun)
userInfo:nil
repeats:YES];
}
viewDidLoad
{
[NSThread detachNewThreadSelector:#selector(createTimmer)
toTarget:self withObject:nil];
...
}
When I debug, the method createTimer runs ok, but the method does timerRun not run?
Just creating a timer doesn't start it running. You need to both create it and schedule it.
You're actually going to have to do slightly more work than that if you want it to run on a background thread. NSTimers attach to NSRunloops, which are the Cocoa form of an event loop. Each NSThread inherently has a a run loop but you have to tell it to run explicitly.
A run loop with a timer attached can run itself indefinitely but you probably don't want it to because it won't be managing autorelease pools for you.
So, in summary, you probably want to (i) create the timer; (ii) attach it to that thread's run loop; (iii) enter a loop that creates an autorelease pool, runs the run loop for a bit and then drains the autorelease pool.
Code will probably look like:
// create timer
timer = [NSTimer timerWithTimeInterval:1.0
target:self
selector:#selector(timerRun)
userInfo:nil
repeats:YES];
// attach the timer to this thread's run loop
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
// pump the run loop until someone tells us to stop
while(!someQuitCondition)
{
// create a autorelease pool
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
// allow the run loop to run for, arbitrarily, 2 seconds
[[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:2.0]];
// drain the pool
[pool drain];
}
// clean up after the timer
[timer invalidate];
You have to schedule a timer for it to run. They get attached to a run loop, which in turn updates the timer as necessary.
You can either change createTimer to
[NSTimer scheduledTimerWithTimeInterval:1.0
target:self
selector:#selector(timerRun)
userInfo:nil
repeats:YES];
or add
[[NSRunLoop currentRunLoop] addTimer:timer forModes:NSRunLoopCommonModes];
The method signature that you use in scheduledTimerWithTimeInterval:target:selector:userInfo:repeats: must have an argument for the NSTimer as it passes itself as an argument.
You should change your message signature to:
(void)timerRun:(NSTimer *)timer;
You don't need to do anything with the argument, but it should be there. Also in createTimer the selector will become #selector(timerRun:) as it now accepts an argument:
timer = [NSTimer timerWithTimeInterval:1.0
target:self
selector:#selector(timerRun:)
userInfo:nil
repeats:YES];