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 = ...
Related
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
Currently I am developing a game which needs a stop watch say 1 minute,when user taps the play button it enters the game screen,I want the to run the stop watch count down of 1 minute 01:00,00:59,00:58 etc. For that reason I searched and found NSTimer would be the ideal choice to implement a stop watch.Hence I took a label,created an instance of NSTimer,assigned time interval and started decrementing the value in timer label,i.e.:
-(void)viewDidAppear:(BOOL)animated
{
self.stopWatchTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(viewWillAppear:) userInfo:nil repeats:YES];
[super viewDidAppear:YES];
}
-(void)viewWillAppear:(BOOL)animated
{
static int currentTime = 60;
int newTime = currentTime--;
int minutesRemaining = newTime / 60; // integer division, truncates fractional part
int secondsRemaining = newTime % 60; // modulo division
self.timerLabel.text = [NSString stringWithFormat:#"%02d:%02d", minutesRemaining, secondsRemaining];
if ([self.timerLabel.text isEqualToString:#"00:00"])
{
[stopWatchTimer invalidate];
}
[super viewWillAppear:YES];
}
The problem here is the timer starts running 01:00,00:59,00:58 and goes on,say at 53rd second,I navigated to another view and came back,it is running from 00:53,00:52 and so on,but I want it to run from 01:00 and for that I implemented invalidating NSTimer in viewDidDisappear i.e.
-(void)viewDidDisappear:(BOOL)animated
{
if ([stopWatchTimer isValid])
{
[stopWatchTimer invalidate];
self.stopWatchTimer = nil;
}
[super viewDidDisappear:YES];
}
Still the same issue exists!
Done lots of Research on the issue and found no answer useful and working.
Can some one please guide me,any help is appreciated.
Thanks every one in advance :)
You are use the selector viewWillAppear for the timer. viewWillAppear is a method on a viewController that gets called when the view appears on screen, you should not call it yourself. Instead, create your own method that decrements the timer:
-(void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
self.stopWatchTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(updateTime:) userInfo:nil repeats:YES];
currentTime = 60; // This could be an instance variable
self.timerLabel.text = #"01:00";
}
-(void)updateTime {
int newTime = currentTime--;
int minutesRemaining = newTime / 60; // integer division, truncates fractional part
int secondsRemaining = newTime % 60; // modulo division
self.timerLabel.text = [NSString stringWithFormat:#"%02d:%02d", minutesRemaining, secondsRemaining];
if ([self.timerLabel.text isEqualToString:#"00:00"])
{
[self.stopWatchTimer invalidate];
}
}
-(void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];
if ([self.stopWatchTimer isValid])
{
[self.stopWatchTimer invalidate];
self.stopWatchTimer = nil;
}
}
With this technique the timer is responsible for calling every second, but you will probably have timing issues after some seconds. To have a more accurate timing, you should store the time that you started the countdown and then on every updateTime call, compare the current time with the stored started time.
Add to your interface:
#property (nonatomic) NSTimeInterval startTime;
then in the implementation:
-(void)viewDidAppear:(BOOL)animated
{
self.startTime = [NSDate timeIntervalSinceReferenceDate];
self.duration = 60; // How long the countdown should be
self.stopWatchTimer = [NSTimer scheduledTimerWithTimeInterval:0.1
target:self
selector:#selector(updateTime)
userInfo:nil
repeats:YES];
self.timerLabel.text = #"01:00"; // Make sure this represents the countdown time
}
-(void)updateTime {
int newTime = self.duration - (round([NSDate timeIntervalSinceReferenceDate] - self.startTime));
int minutesRemaining = newTime / 60; // integer division, truncates fractional part
int secondsRemaining = newTime % 60; // modulo division
self.timerLabel.text = [NSString stringWithFormat:#"%02d:%02d", minutesRemaining, secondsRemaining];
if (newTime < 1)
{
[self.stopWatchTimer invalidate];
/* Do more stuff here */
}
}
-(void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];
if ([self.stopWatchTimer isValid])
{
[self.stopWatchTimer invalidate];
self.stopWatchTimer = nil;
}
}
Some extra (unrelated) comments on the code:
when implementing viewDidDisappear: pass the animated parameter to the call to super:
[super viewDidDisappear:animated];
when implementing viewDidAppear: pass the animated parameter to the call to super, also, make sure you call super first this in the method, before doing anything else
I have a -(void) method being executed and at one point it gets to a while loop that gets values from the accelerometer directly the moment it asks for them
I went throughout the documentation regarding the NSTimer class but I couldn't make sense of how exactly I am to use this object in my case :
e.g.
-(void) play
{
......
...
if(accelerationOnYaxis >0 && accelerationOnYaxis < 0.9 )
{
startTimer;
}
while(accelerationOnYaxis >0 && accelerationOnYaxis < 0.9)
{
if(checkTimer >= 300msec)
{
printOut_AccelerationStayedBetweenThoseTwoValuesForAtLeast300msecs;
break_Out_Of_This_Loop;
}
}
stopTimerAndReSetTimerToZero;
.....
more code...
....
...
}
Any help?
You cannot do it with NSTimer, because it needs your code to exit in order to fire. NSTimer uses the event loop to decide when to call you back; if your program holds the control in its while loop, there is no way for the timer to fire, because the code that checks if it's time to fire or not is never reached.
On top of that, staying in a busy loop for nearly a second and a half is going to deplete your battery. If you simply need to wait for 1.4s, you are better off calling sleepForTimeInterval:, like this:
[NSThread sleepForTimeInterval:1.4];
You can also use clock() from <time.h> to measure short time intervals, like this:
clock_t start = clock();
clock_t end = start + (3*CLOCKS_PER_SEC)/10; // 300 ms == 3/10 s
while(accelerationOnYaxis >0 && accelerationOnYaxis < 0.9)
{
if(clock() >= end)
{
printOut_AccelerationStayedBetweenThoseTwoValuesForAtLeast300msecs;
break_Out_Of_This_Loop;
}
}
NSTimer works a little different than you want. What you need is a counter for your timer, to get how many times it looped. If your counter gets on 14 (if it's an integer), you can invalidate it.
//start timer
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.1
target:self
selector:#selector(play:)
userInfo:nil
repeats:YES];
//stop timer
[timer invalidate];
You can create your function without that while.
- (void)play {
......
...
counter++; //declare it in your header
if(counter < 14){
x++; //your integer needs to be declared in your header to keep it's value
} else {
[timer invalidate];
}
useValueofX;
}
Take a look at the documentation.
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Change the time interval of a Timer
So I have a timer:
timer=[NSTimer scheduledTimerWithTimeInterval:2 target:self selector:#selector(createNewImage) userInfo:nil repeats:YES];
And I would like that the timer decrease every ten seconds, that scheduledTimerWithTimeInterval goes to 1.5 after ten seconds then to 1.0 after 10 seconds... Is it possible to do this, and if it is possible, how can I do it?
You can't modify a timer after you created it. To change the timer interval, invalidate the old timer and create a new one with the new interval.
You don't have to use several timers, all you have to do is add a variable to use for the time interval, then create a method that invalidates the timer, changes the variable and starts the timer again. For instance you could make a method that starts the timer.
int iTimerInterval = 2;
-(void) mTimerStart {
timer = [NSTimer scheduledTimerWithTimeInterval:iTimerInterval target:self selector:#selector(createNewImage) userInfo:nil repeats:YES];
}
-(void) mTimerStop {
[timer invalidate];
iTimerInterval = iTimerInterval + 5;
[self mTimerStart];
}
This would be the simple way to decrease the timer interval and keep the timer going, but I would personally prefer using the one below, because it makes sure that the timer has only ran once, that way it will not duplicate the instance, forcing your app to become glitchy and it also makes things easier for you.
int iTimerInterval = 2;
int iTimerIncrementAmount = 5;
int iTimerCount;
int iTimerChange = 10; //Variable to change the timer after the amount of time
bool bTimerRunning = FALSE;
-(void) mTimerToggle:(BOOL)bTimerShouldRun {
if (bTimerShouldRun == TRUE) {
if (bTimerRunning == FALSE) {
timer = [NSTimer scheduledTimerWithTimeInterval:iTimerInterval target:self selector:#selector(mCreateNewImage) userInfo:nil repeats:YES];
bTimerRunning = TRUE;
}
} else if (bTimerShouldRun == FALSE) {
if (bTimerRunning == TRUE) {
[timer invalidate];
bTimerRunning = FALSE;
}
}
}
-(void) mCreateNewImage {
//Your Code Goes Here
if (iTimerCount % iTimerChange == 0) { //10 Second Increments
iTimerInterval = iTimerInterval + iTimerIncrementAmount; //Increments by Variable's amount
[self mTimerToggle:FALSE]; //Stops Timer
[self mTimerToggle:TRUE]; //Starts Timer
}
iTimerCount ++;
}
-(void) mYourMethodThatStartsTimer {
[self mTimerToggle:TRUE];
}
I didn't finish all of the coding, but this is most of what you will need. Just change a few things and you'll be good to go!
You will need a set or sequence of timers, one for each different time interval. Stop/invalidate one timer and start the next timer when you want to change to the next time interval in your time sequence.
I have a countdown timer in my game and I'm trying to figure out how to make it so that it shows two decimal places and records with 2 decimal places in my table. Right now it counts down as a whole number and records as a whole number. Any ideas?
-(void)updateTimerLabel{
if(appDelegate.gameStateRunning == YES){
if(gameVarLevel==1){
timeSeconds = 100;
AllowResetTimer = NO;
}
timeSeconds--;
timerLabel.text=[NSString stringWithFormat:#"Time: %d", timeSeconds];
}
countdownTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(updateTimerLabel) userInfo:nil repeats:YES];
To have sub-second updates, the timer's interval needs to be < 1. But the precision of NSTimer is just around 50 ms, so scheduledTimerWithTimeInterval:0.01 will not work.
Moreover, the timer can be delayed by various activities, so using timeSeconds will lead to inaccurate timing. The usual way is compare the NSDate now with the date when the timer starts. However, as this code is for a game, the current approach may cause less frustration to players esp. if the program or background processes consumes lots of resources.
The first thing to do is to convert the countdownTimer to sub-second interval.
countdownTimer = [NSTimer scheduledTimerWithTimeInterval:0.67 target:self selector:#selector(updateTimerLabel) userInfo:nil repeats:YES];
Then, don't count down the time by seconds, but centiseconds:
if(appDelegate.gameStateRunning == YES){
if(gameVarLevel==1){
timeCentiseconds = 10000;
AllowResetTimer = NO;
}
}
timeCentiseconds -= 67;
Finally, divide by 100 in the output:
timerLabel.text=[NSString stringWithFormat:#"Time: %d.%02d", timeCentiseconds/100, timeCentiseconds%100];
Alternatively, use a double:
double timeSeconds;
...
if(appDelegate.gameStateRunning == YES){
if(gameVarLevel==1){
timeSeconds = 100;
AllowResetTimer = NO;
}
}
timeSeconds -= 0.67;
timerLabel.text=[NSString stringWithFormat:#"Time: %.2g", timeSeconds];