How to make a button appear and disappear throughout a timer - ios

Question

I have this app which has a timer in it and I want to be able to display a button at random points in that timer. Sort Of like a game setting where you have to get the button to get more time before it disappears. I already have some code , but the problem is that the timer that i already have is being messed up ( i can tell because it is linked to a label. It messed up because it goes down by 2 instead of 1 and this only happens when i have the code to make the button appear and disappear with the timer.
Here is the code to my timer that is being messed up:
-(IBAction)Ready:(id)sender {
[self performSelector:#selector(TimerDelay) withObject:nil afterDelay:1.0];
[self performSelector:#selector(randomTimer) withObject:nil afterDelay:0.5];
}
-(void)TimerDelay {
MainInt = 36;
timer = [NSTimer scheduledTimerWithTimeInterval:1.0
target:self
selector:#selector(countDownDuration)
userInfo:nil
repeats:YES];
}
Here is the code to the button:
-(IBAction)Ready:(id)sender { //the same ready action as above
[self performSelector:#selector(TimerDelay) withObject:nil afterDelay:1.0];
[self performSelector:#selector(randomTimer) withObject:nil afterDelay:0.5];
}
-(void)TimerDelay {
MainInt = 36;
timer = [NSTimer scheduledTimerWithTimeInterval:1.0
target:self
selector:#selector(countDownDuration)
userInfo:nil
repeats:YES];
}
- (void)randomTimer {
NSInteger randomTime = arc4random_uniform(0); //Some number between 0 and 9
timer = [NSTimer scheduledTimerWithTimeInterval:randomTime
target:self
selector:#selector(showButton)
userInfo:nil
repeats:NO];
}
- (void)showButton {
if(self.plus5.hidden == YES) {
self.plus5.hidden = NO;
}
else {
self.plus5.hidden = YES;
}
[self TimerDelay]; //Call random timer function again to run this method at a future random time
}

Answer 1

You are calling "randomTimer" and "TimerDelay" (this should be "timerDelay") one after the other and scheduling and REscheduling "timer".
I think you should reconsider your architecture, here...
EDIT: Use just one timer and let it manage your button.
- (void)somewhereInYourCode
{
shouldShowButton = YES;
timer = [NSTimer scheduledTimerWithTimeInterval:1.0
target:self
selector:#selector(timeFired)
userInfo:nil
repeats:YES];
}
- (void)timeFired
{
// Here your countdown and...
if (shouldShowButton) {
NSInteger randomTimeInt = arc4random_uniform(9); // as suggested by Bergasms
float randomTimeFloat = randomTimeInt;
[self performSelector:#selector(showButton) withObject:nil afterDelay:randomTimeFloat];
shouldShowButton = NO;
}
}
This way your timer won't (probably) mess up.

Answer 2

This:
arc4random_uniform() will return a uniformly distributed random number
less than upper_bound.
is one of your problems.
NSInteger randomTime = arc4random_uniform(0); //Some number between 0 and 9
needs to be
NSInteger randomTime = arc4random_uniform(9); //Some number between 0 and 9
I cannot say for the rest of your code. But the line you have will always return 0, which means the random timer will always execute instantly.