I am very new in Iphone Development. I have an issue . I am using a NSTimer which update a UiLabel in every second. now i have two problem :
when my app goes in background and after it when i open app . app goes hangs.
if i goes next or back on other ui screen then wen i comes on timer screen then my label again shows 0.
can anyone help me.
code which i am using :
timer = [NSTimer scheduledTimerWithTimeInterval: 1.0 target:self selector:#selector(updateCountdown) userInfo:nil repeats: YES];
-(void) updateCountdown
{
secondsLeft--;
//nits testing
if(secondsLeft == 1)
{
[self.view addSubview:recipePage6View.view];
}
if (secondsLeft<0)
{
[timer invalidate];
timer=nil;
lblDisplayTimer.text =#"00:00:00";
}
else
{
hours = secondsLeft / 3600;
minutes = (secondsLeft % 3600) / 60;
seconds = (secondsLeft %3600) % 60;
lblDisplayTimer.text = [NSString stringWithFormat:#"%02d:%02d:%02d", hours, minutes, seconds];
//lblDisplayTimer.text = [NSString stringWithFormat:#"%02d:%02d",minutes,seconds];
}
}
You need to set up a special background timer task and not have an NSTimer on the main run loop which gets suspended in background. The documentation on how to do this is here
Related
I have CountDown timer like below:
- (void)updateCounterLabel:(NSTimer *)theTimer {
if(secondsLeft > 0 ){
secondsLeft -- ;
hours = secondsLeft / 3600;
minutes = (secondsLeft % 3600) / 60;
seconds = (secondsLeft %3600) % 60;
countDownLabel.text = [NSString stringWithFormat:#"%02d:%02d:%02d", hours, minutes, seconds];
}
else{
secondsLeft = timeInterval;
}
-(void)countdownTimer {
if([timer isValid]){
[timer invalidate];
timer = nil;
}
timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:#selector(updateCounterLabel:) userInfo:nil repeats:YES];
}
----My problem is that every time recall this timer it increments like this : secondLeft-3 , secondLeft -5 ,secondLeft - 7..................
Each time my view loads, i create a new timer, but the old ones still exist.in my timer's action method, i am decrementing an index variable that keeps track of the seconds, and each timer runs that method every time it fires. So, if i have three timers, the index will decrements by three each time.
For example:
First Load: 60, 59, 58...
Second Load: 60, 58, 56...
Third Load: 60, 57, 54...
Question : How can i restart or recreate a timer without above problem? somebody help me out pls.
The
timer = [NSTimer scheduledTimerWithTimeInterval:...];
call retains the target (the view controller) while the timer is running,
so that the view controller
is never deallocated and the timer continues to run even if the view controller
is popped off the navigation stack or dismissed.
Therefore, if the view is loaded again, you have two instances of the view controller and
therefore two timers, which both decrement the same global variable secondsLeft.
This hopefully explains why the value is decremented by two each second.
As a solution, you can create the timer in viewWillAppear, and invalidate it
in viewWillDisappear.
I am developing a QuiZ app. It needs a countdown timer, In that I want to start a timer at 75:00.00 (mm:ss.SS) and decrease it to 00:00.00 (mm:ss.SS) by reducing 1 millisecond. I want to display an alert that Time UP! when time reaches to 00:00.00 (mm:ss.SS).
I am displaying the time by following below link
Stopwatch using NSTimer incorrectly includes paused time in display
Here is a simple solutions to your problem.
Declarations
#interface ViewController : UIViewController
{
IBOutlet UILabel * result;
NSTimer * timer;
int currentTime;
}
- (void)populateLabelwithTime:(int)milliseconds;
-(IBAction)start;
-(IBAction)pause;
#end
Definition
- (void)viewDidLoad
{
[super viewDidLoad];
currentTime = 270000000; // Since 75 hours = 270000000 milli seconds
}
-(IBAction)start{
timer = [NSTimer scheduledTimerWithTimeInterval:.01 target:self selector:#selector(updateTimer:) userInfo:nil repeats:YES];
}
-(IBAction)pause{
[timer invalidate];
}
- (void)updateTimer:(NSTimer *)timer {
currentTime -= 10 ;
[self populateLabelwithTime:currentTime];
}
- (void)populateLabelwithTime:(int)milliseconds {
int seconds = milliseconds/1000;
int minutes = seconds / 60;
int hours = minutes / 60;
seconds -= minutes * 60;
minutes -= hours * 60;
NSString * result1 = [NSString stringWithFormat:#"%#%02dh:%02dm:%02ds:%02dms", (milliseconds<0?#"-":#""), hours, minutes, seconds,milliseconds%1000];
result.text = result1;
}
Use following code for reducing timer.
double dblRemainingTime=60; //1 minute
if(dblRemainingTime >0)
{
dblRemainingTime -= 1;
int hours,minutes, seconds;
hours = dblRemainingTime / 3600;
minutes = (dblRemainingTime - (hours*3600)) / 60;
seconds = fmod(dblRemainingTime, 60);
[lblRemainingTime setText:[NSString stringWithFormat:#"%02d:%02d",minutes, seconds]];
}
else
alert('Time up buddy');
I'm looking to make a UILabel display the current progress of a timer. Right now to get the current time left I call [timer1 timeLeft]; which returns an int. In this way I can update the label ONCE, at one instant. In what way can I update the label (mainLabel) constantly so that it is always displaying the current timer progress while being somewhat resource efficient?
Thanks for all your help!
Use following code for Countdown timer.
dblElapsedSeconds=0.0; //Declare this in header
tmrElapsedTime = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(updateElapsedTime) userInfo:nil repeats:YES]; //Declare timer variable in header
-(void)updateElapsedTime
{
dblElapsedSeconds += 1;
//double seconds = [[NSDate date] timeIntervalSinceDate:self.startTime];
int hours,minutes, lseconds;
hours = dblElapsedSeconds / 3600;
minutes = (dblElapsedSeconds - (hours*3600)) / 60;
lseconds = fmod(dblElapsedSeconds, 60);
[lblTimeElapsed setText:[NSString stringWithFormat:#"%02d:%02d",minutes, lseconds]];
}
in my application i have an UILabel showing a time updated every second.
I have also draggable objects in the screen.
When I hide the label or i stop the timer everything is perfect but when i start the timer the animation performance of dragging objects go down.
I put the UILabel updating in a separate thread but no luck.
I need help friends :)
This is my code:
self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(onTimer:) userInfo:nil repeats:YES];
-(void) onTimer:(NSTimer *)timer;
{
timeInterval ++;
int hours = (int)timeInterval / 3600;
int minutes = (timeInterval %3600)/ 60;
int seconds = ((timeInterval%3600)%60);
NSString *timeDiff = [NSString stringWithFormat:#"%d:%02d:%02d", hours,minutes,seconds];
[NSThread detachNewThreadSelector:#selector(setText:) toTarget:self.time withObject:timeDiff];
}
I am working on a count down timer and am having trouble getting the if statement to stop the timer when the count is less that 0. Any guidance on solving this would be greatly appreciated. Thanks in advance for your help..
-(void) startCountdown{
time = 90;
//NSLog[#"Time Left %d Seconds", time];
//This timer will call the function updateInterface every 1 second
myTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(updateInterface:) userInfo:nil repeats:YES];
}
-(void) updateInterface:(NSTimer*)theTimer{
if(time >= 0){
time --;
CountDownText.text = [NSString stringWithFormat:#"%d", time];
NSLog(#"Time Left %d Seconds", time);
}
else{
CountDownText.text =#"Times Up!";
NSLog(#"Times Up!");
// Timer gets killed and no longer calls updateInterface
[myTimer invalidate];
}
}
I tested your code and it worked perfectly and the timer stopped at -1. So my best guess is that time might be declared as unsigned value, so it never becomes less than zero.
Looks like your countdown won't stop until it gets to -1 (instead of 0) because you're checking for greater-than-or-equal to zero and then decrementing (and then displaying).
Either decrement first and then check if time is greater-than zero:
-(void) updateInterface:(NSTimer*)theTimer{
time --;
if(time > 0){
CountDownText.text = ...
or check if time is greater-than 1:
-(void) updateInterface:(NSTimer*)theTimer{
if(time > 1){
time --;
CountDownText.text = ...