how to add timer to loop. i am making a urlConnection so i want that the loop execute for a time and if there is no connection it should exit.
Does it work.....
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:0.1f]];
Thanks in advance.
NSURLConnection has a method - (void)scheduleInRunLoop:(NSRunLoop *)aRunLoop forMode:(NSString *)mode. Is this what you're looking for?
Sounds like you want #selector(timerWithTimeInterval:target:selector:userInfo:repeats:).
"Returns a new NSTimer that, when added to a run loop, will fire after a specified number of seconds." See http://developer.apple.com/iphone/library/documentation/Cocoa/Reference/Foundation/Classes/NSTimer_Class/Reference/NSTimer.html
Set repeats:YES and invalidate the timer after your timeout value is reached.
If you are trying to make your url connection attempt time out after a certain interval, you would be far better off looking at the timeout value on NSURLRequest. Synchronous connections should be avoided wherever possible.
Related
I have a problem with NSTimer. I start and repeat it every 100ms and I have a counter to check if i runed 10s. The problem is it stoped in near 1 minute, not in 10s.
Here is my code
timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:#selector(checkTimer) userInfo:nil repeats:YES];
-(void)checkTimer
{
timerCount += 1;
if(timerCount == 1)
{
NSLog(#"start");
}
if(timerCount == 103)
{
NSLog(#"i got it");
}
}
here is the log:
2012-11-19 08:57:42.063 Karagram[11708:540b] start
[Switching to process 8707 thread 0x2203]
2012-11-19 08:58:39.514 Karagram[11708:540b] i got it
I don't understand why it wrong. Somebody can tell me why?
Thanks.
NSTimers aren't guaranteed to be accurate to within more than 100 ms or so. The NSTimer documentation says:
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. Because of the various
input sources a typical run loop manages, the effective resolution of
the time interval for a timer is limited to on the order of 50-100
milliseconds. If a timer’s firing time occurs during a long callout or
while the run loop is in a mode that is not monitoring the timer, the
timer does not fire until the next time the run loop checks the timer.
Therefore, the actual time at which the timer fires potentially can be
a significant period of time after the scheduled firing time.
By having it fire every 100ms you're compounding the error, because if it's off 50 ms every 100ms, by the time 10s has passed it could be quite far from what you expect.
If you're wanting to take some action after 10s, why not just set the timer to fire after 10s?
NSLog( #"start" );
timer = [NSTimer scheduledTimerWithTimeInterval:10.0 target:self selector:#selector(checkTimer) userInfo:nil repeats:YES];
-(void)checkTimer
{
NSLog(#"i got it");
}
Also, are you doing your streaming on the main thread? NSTimers work on the main runloop, so if you're blocking the main thread, timers aren't going to fire until it's unblocked.
I have to stop and restart a simple method that takes from 1 to 2 seconds to execute. How can this be accomplished? I have already tried [NSObject cancelPreviousPerformRequestsWithTarget:self] but it works only with performselector after delay. I have also tried to create a new thread but it doesn't seem to work...
This is my method:
-(IBAction)MyMethod
{
NSLog(#"start");
//Here is the code that takes time to execute. It regards UI intervention,graphic calculation, x and y position etc.
NSLog(#"end");
}
I want this effect: one click on the linked UIButton and the method start (so print start log and end log). If I click the linked UIButton before the NSLog is printed, the method must stop. Is this possible?
You'll want to use a background task. I would suggest subclassing and using a NSOperation and checking for isCancelled within the body of main. See Apple's documentation on using NSOperation and NSOperationQueue.
Well, to do this with threads what I usually do is dividing things into 3 sections:
start.
processing.
finish.
And it looks like this:
-(void)start:(id)sender{
//prepare everything and anything
[NSThread detachNewThreadSelector:#selector(processing:) toTarget:self withObject:nil];
}
-(void)processing:(id)sender{
//Perform all your calculations, you can't modify UI elements here
[self performSelectorOnMainThread:#selector(finish:) withObject:nil waitUntilDone:NO];
}
-(void)finish:(id)sender{
//Wrap everything up and do any modifications to the UI
}
Now, to cancel this you could add maybe use:
Cancels perform requests previously registered with
performSelector:withObject:afterDelay:.
+ (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget selector:(SEL)aSelector object:(id)anArgument
I am working on an application that needs a method to be called at a certain time (15 minutes past the hour to be exact). Is there a way to make this happen without consuming a ton of CPU and battery life? I've tried searching and just can't find an answer anywhere.
They made this really easy. Alloc an NSTimer and initialize it with the fire date, using:
-(id)initWithFireDate:(NSDate *)date
interval:(NSTimeInterval)seconds
target:(id)target
selector:(SEL)aSelector
userInfo:(id)userInfo
repeats:(BOOL)repeats
then add it to the run loop using:
-(void)addTimer:(NSTimer *)aTimer forMode:(NSString *)mode
on the run loop, e.g. [NSRunLoop currentRunLoop]. Don't know if this will wake the device, or prevent it from sleeping.
edit some example code
// start in 5 minutes
NSDate *date = [NSDate dateWithTimeIntervalSinceNow:300];
// fire every minute from then on
NSTimer *t = [[NSTimer alloc]
initWithFireDate:date
interval:60
target:self
selector:#selector(stuff:) // -(void)stuff:(NSTimer*)theTimer
userInfo:nil
repeats:YES
];
// make it work
[[NSRunLoop currentRunLoop] addTimer:t forMode:NSDefaultRunLoopMode];
and
-(void)stuff:(NSTimer*)theTimer
{
if ( done ) [theTimer invalidate];
}
If you need this to happen while your application is not running, have a look a UILocalNotification in iOS 4.0. It's unclear whether your application is running at the time that you need this notification or not, but in either case this class should get you pointed in the right direction.
http://developer.apple.com/iphone/library/documentation/iPhone/Reference/UILocalNotification_Class/Reference/Reference.html#//apple_ref/occ/cl/UILocalNotification
Okay, I have searched online and even looked in a couple of books for the answer because I can't understand the apple documentation for the NSTimer. I am trying to implement 2 timers on the same view that each have 3 buttons (START - STOP - RESET).
The first timer counts down from 2 minutes and then beeps.
The second timer counts up from 00:00 indefinitely.
I am assuming that all of the code will be written in the methods behind the 3 different buttons but I am completely lost trying to read the apple documentation. Any help would be greatly appreciated.
Basically what you want is an event that fires every 1 second, or possibly at 1/10th second intervals, and you'll update your UI when the timer ticks.
The following will create a timer, and add it to your run loop. Save the timer somewhere so you can kill it when needed.
- (NSTimer*)createTimer {
// create timer on run loop
return [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(timerTicked:) userInfo:nil repeats:YES];
}
Now write a handler for the timer tick:
- (void)timerTicked:(NSTimer*)timer {
// decrement timer 1 … this is your UI, tick down and redraw
[myStopwatch tickDown];
[myStopwatch.view setNeedsDisplay];
// increment timer 2 … bump time and redraw in UI
…
}
If the user hits a button, you can reset the counts, or start or stop the ticking. To end a timer, send an invalidate message:
- (void)actionStop:(id)sender {
// stop the timer
[myTimer invalidate];
}
Hope this helps you out.
I would follow Jonathan's approach except you should use an NSDate as your reference for updating the UI. Meaning instead of updating the tick based on the NSTimer, when the NSTimer fires, you take the difference between NSDate for now and your reference date.
The reason for this is that the NSTimer has a resolution of 50-100 ms which means your timer can become pretty inaccurate after a few minutes if there's a lot going on to slow down the device. Using NSDate as a reference point will ensure that the only lag between the actual time and the time displayed is in the calculation of that difference and the rendering of the display.
I'm creating a Tic tac toe game, in that after click made by user automatically the cpu will respond. I want the cpu response after 0.50 seconds, the sleep() function takes too many time, I don't want that much time, is there any other way to do so?
use
[self performSelector:#selector(FunctionName) withObject:nil afterDelay:0.5 ];
usleep(500000)
use sleep property and give (more milliseconds)