My app tracks a user with CLLocationManager. In the delegate call didUpdateToLocation I do all the fun stuff of saving their position. However, I needed a way to test if they had stopped. That away I could stop recording locations and consider their trip over. So I have a NSTimer in CCLocationManager that gets added and removed every time didUpdateToLocation is called. That away it will be initiated when the user stops and CLLocationManager stops getting called.
The only way that I could ever get the NSTimer to work is to do:
[[NSRunLoop mainRunLoop] addTimer:userStoppedMovingTimer forMode:NSRunLoopCommonModes];
Then to remove it:
[userStoppedMovingTimer invalidate];
I've never had to add timers like this in the past. Could someone shed some light as to why this is?
From the documentation:
There are three ways to create a timer:
Use the scheduledTimerWithTimeInterval:invocation:repeats: or
scheduledTimerWithTimeInterval:target:selector:userInfo:repeats: class
method to create the timer and schedule it on the current run loop in
the default mode.
Use the timerWithTimeInterval:invocation:repeats: or
timerWithTimeInterval:target:selector:userInfo:repeats: class method
to create the timer object without scheduling it on a run loop. (After
creating it, you must add the timer to a run loop manually by calling
the addTimer:forMode: method of the corresponding NSRunLoop object.)
Allocate the timer and initialize it using the
initWithFireDate:interval:target:selector:userInfo:repeats: method.
(After creating it, you must add the timer to a run loop manually by
calling the addTimer:forMode: method of the corresponding NSRunLoop
object.)
You were probably using option 1 previously, and now you're using option 2 or 3.
Related
I'm working on a card game and trying to get cards to deal one after the other. I have a method that animated a card from the deck to a player, and in viewDidLoad I call this method four times. The problem is all four cards get dealt simultaneously. How do I stop a method in its tracks for a period of time?
I know that the scheduledTimerWithTimeInterval method calls another method after a delay, but I'm looking for a way to interrupt the current method after calling the deal method once and then continuing with the rest of the current method. sleep() also doesn't work. I tried putting it between calls to the deal method, but it just executed all the sleep()s and then did all the animation at once again. Any help is much appreciated. Thanks!
You are going down the wrong road. Attempting to sleep a method is not the way to approach this. You want to break the task into steps to be performed serially and perform each step only after the previous step is completed.
Say you have a variable called 'cardCounter' and one called 'cardMax'. Then you have a method called 'dealCard'. In viewDidAppear you intialize 'cardCounter` to zero and 'cardMax' to 4 (or however many cards are to be dealt. Then you call the 'dealCard' method.
(actually, you probably want a method called newGame or something since you will likely want to have multiple games and you don't want to tie your game setup to the viewDidAppear event. So in viewDidAppear you would call 'newGame' and do your initialization there.)
- (void)dealCard {
cardCounter++;
if (cardCounter > cardMax){
// all cards are dealt
// call some method to start game
// or do any other set up;
} else {
// call some method to animate the card
// using core animation with a completion handler?
// using a ^block with a completion handler?
// either way, in the completion handler call
// 'dealCard' again
}
A hint. Create a setup method which is called from your init only once! In that setup method you can work with `performSelector" as tomi said. The Selector is "your" method that moves a card from the deck to the player.
(void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay
I'm having serious problem whenever I pause the game, since most of my performSelector: has delay, so it will not execute immediately, but thing goes bad if I'm pausing the game then the performSelector is still calling... How should I overcome this?
I know there is one function under NSObject to cancel all the requests but that's not really what i'm looking for because I want the method to continue execute if the player resume the game.
According to cocos2d Best Practices you should not use performSelector:afterDelay directly but use cocos2d scheduler instead:
Try NOT to use Cocoa’s NSTimer. Instead use cocos2d’s own scheduler.
If you use cocos2d scheduler, you will have:
automatic pause/resume.
when the CCLayer (CCScene, CCSprite, CCNode) enters the stage the timer will be automatically activated, and when it leaves the stage it will be automatically deactivated.
Your target/selector will be called with a delta time
Here's how you schedule your method (assuming self is a CCNode):
[self schedule: #selector(tick2:) interval:0.5];
Don't forget to unschedule it in -tick2: if you want to call it once.
For some reason when I push down (click and hold) on any control, the NSTimer in my App freezes and does not fire until I release the mouse button. It simply does not fire while I have the mouse pressed. This is fine for short periods, but it also freezes if I have a popup menu open, or a combobox dropped down.
I'm not sure if there is something I missed, but it seems like this is incorrect behavior.
I want to be able to click the down arrow of an NSPopUpButtonCell (or even click and hold an NSTableView) without the entire NSTimer freezing (which redraws an NSView).
Any comments / suggestions would be appreciated.
The NSTimer is added to the currentRunLoop with mode NSDefaultRunLoopMode.
While the mouse is down, the run loop is in the NSEventTrackingRunLoopMode. Therefore, any event that's not received onto the EventTracking event queue won't be serviced until the runloop returns to the appropriate mode.
The way around this is to add the timer to the runloop for both modes (default and event tracking).
Instead of adding two or more timers to different runloops or using multithreading (as you won't then be able to update the UI from another thread) simply add the timer to the NSRunLoopCommonModes:
NSTimer *myTimer = [NSTimer timerWithTimeInterval:RefreshInterval target:self selector:#selector(doWork) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:myTimer forMode:NSRunLoopCommonModes];
Assuming you're just dealing with one thread in your application, what you described is perfectly expected. By default, NSTimer's are added to the current NSRunLoop which, in your case, is also responsible for dealing with UI interaction. When it gets tied up with handling UI interaction, it can't check your timer and "fire" it.
A solution is to use multi-threading so as to avoid this tie-up. Here's a nice blog post on this very subject: http://blog.narent.com/?p=21
EDIT: See Dave's post for an alternative (and more elegant IMO) solution
Also see:
NSTimer doc
NSRunLoop doc
Threading programming guide
I'm currently using the snippet of code presented below to fire some methods every second. My app is running in the background. The problem is that if the computer wakes up after a sleep period the timer wants to retroactively fire all the methods it has missed. Similar issues come up if the user were to change the System Clock time.
Basically I want to implement the proper timer method that will have my methods called only every current second. If a second (or minute or hour or day) has passed and for whatever reason the methods weren't called I want my app to just continue from the current moment in time.
Also, can we keep this while using NSTimer?
Thanks!
-(void)start
{
NSTimer * timer = [NSTimer timerWithTimeInterval:1.0 target:self selector:#selector(tasks:) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:timer forMode: NSDefaultRunLoopMode];
}
To handle the big time changes you can use the link UIApplicationSignificantTimeChangeNotification and unregister/reregister your timer.
To deal with the sleep issue, you can unregister and then reregister your timer whenever the machine goes to sleep and wakes up. See this technical note for information on how to do that. This solution won't work for changing the system time, though.
I have a -(void)save method that is called when a user clicks a navigation bar button. In that method is the following NSTimer:
[NSTimer scheduledTimerWithTimeInterval:.25f target:self selector:#selector(flashBackgroundRed) userInfo: nil repeats: flashRepeat];
The timer repeats 4 times since the flashBackgroundRed keeps a count and sets flashRepeat to NO after 4 hits. All works well the first time a user clicks to save. But if the user keeps hitting save with incorrect data, I keep them on the current view. For some reason, flashes get increasing faster. As if each one is 25% of the previous one's interval. I'm not retaining this timer. It only lives in the save method.
If the user clicks the cancel button, viewB (one with NSTimer) is popped and viewA displays. Going from viewA back to viewB seems to reset the timer invterval. But the increasingly fast flashes cycle starts again. Any ideas?
NSTimer is retained by the run loop as long as it is scheduled.
It sounds like the problem is that you keep creating equivalent repeating timers at slightly different times, so they visually mesh together into one effect with a different frequency than you want. Try storing a reference to the timer and invalidating it when you're going to create a new one.
It sounds like you are scheduling more timers than you intend to.
Once scheduled, timers are retained until invalidated. Repeating timers must be manually invalidated.
The repeats argument specifies if the timer will repeat. You can't specify how many times a timer should repeat, only whether or not it will.
Also, the method signature for your selector is wrong. It should look like
-(void)timerFireMethod:(NSTimer*)theTimer
In your timer callback you can determine if you want the timer to continue repeating or not; if not, call [timer invalidate].