Update UILabel continuously — Objective-c - ios

Question

I'm trying to display the count of a timer in a UILabel. The timer works fine but I'm not able to update the label. The NSTimer is set up like this in Class1.
- (void)startTimer {
int timerCount = 5;
timer = [NSTimer scheduledTimerWithTimeInterval:4.0
target:self
selector:#selector(timerDecrement)
userInfo:nil
repeats:YES];
[timer fire];
}
- (void)timerDecrement {
Class2 *cls2 = [[Class2 alloc] init];
timerCount = timerCount-1;
[cls2 updateTimeLeftLabel];
}
+ (int)getTimerCount {
return timerCount;
}
In Class2:
- (void)viewDidLoad {
if (timeLeftLabel == nil) {
timeLeftLabel = [[UILabel alloc] initWithFrame:CGRectMake(200, 70, 120, 30)];
timeLeftLabel.text = #"Time left";
[self.view addSubview:timeLeftLabel];
}
- (void)updateTimeLeftLabel {
NSLog(#"%#", [NSString stringWithFormat:#"%i",
[Class1 getTimerCount]]);
timeLeftLabel.text = [NSString stringWithFormat:#"Time left: %i",
[Class1 getTimerCount]];
}
The correct timer value is logged but the UILabel isn't updated at all. What's wrong?

Answer 1

Try to make timerCount as a #property of your class or static.

Answer 2

You create a new instance of the Class2 and do not present it. You should store instance of Class2 somewhere and work with it.

Answer 3

I needed to update count on my UIButton so i have done like this
-(void)viewDidLoad {
self.myLeagueTimer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:#selector(updateCountdown) userInfo:nil repeats: YES];
}
- (int)timeIndervalRemain {
NSDate *currentTime = [NSDate date];
return (TIME_INTERVAL - [currentTime timeIntervalSinceDate:self.startTime]);
}
-(void) updateCountdown {
if ([self timeIndervalRemain] > 0) {
self.title = [NSString stringWithFormat:#"%d", [self timeIndervalRemain]];
} else {
[self timeExpire];
}
}
-(void) timeExpire {
if (_myLeagueTimer) {
[_myLeagueTimer invalidate];
_myLeagueTimer = nil;
}
}

Answer 4

You can simply pass the time left to the method updating the UILabel as a parameter:
- (void)updateTimeLeftLabel:(NSInteger)timeLeft {
timeLeftLabel.text = [NSString stringWithFormat:#"Time left: %i",
timeLeft];
}
- (void)timerDecrement {
Class2 *cls2 = [[Class2 alloc] init];
timerCount = timerCount-1;
[cls2 updateTimeLeftLabel:timerCount];
}