Call an action at specific intervals in iOS

Question

I am trying to invoke a function that contains ccactioninterval in Cocos3d. I want to call that function at specific time intervals.When I tried NSTimer , i found that it works sometimes and sometimes not.

      NSTimer makeTarget=[NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(createTargets) userInfo:nil repeats:YES];

Here createTargets is the function that contains action events. when i run the function straightit works fine for single time. Problem comes when i try to schedule it. I ve tried different methods already explained for related questions . But nothing worked for me. . . .

Here is the code

-(void) addTargets {      
    NSTimer *makeTarget = [NSTimer scheduledTimerWithTimeInterval:2.0
              target:self selector:@selector(createTargets) userInfo:nil repeats:YES]; 
}

-(void)createTargets {
    CC3MeshNode *target = (CC3MeshNode*)[self getNodeNamed: @"obj1"];    
    int minVal=-5;
    int maxVal=5;    
    float avgVal; 
    avgVal = maxVal- minVal;      
    float Value = ((float)arc4random()/ARC4RANDOM_MAX)*avgVal+minVal ;          
    [target setLocation:cc3v(Value, 5.0, 0.0)];    
    CCActionInterval *moveTarget = [CC3MoveBy actionWithDuration:7.0 moveBy:cc3v(0.0, -10.0, 0.0)];     
    CCActionInterval *removeTarget = [CCCallFuncN actionWithTarget:self selector:@selector(removeTarget:)];       
    [target runAction:[CCSequence actionOne:moveTarget two:removeTarget]];   
}

-(void)removeTarget:(CC3MeshNode*)targ {  
    [self removeChild:targ];  
    targ=nil; 
}

Answer 1

Without much code its hard to tell what you issues is, but here are some things to try apologies if any of this is obvious.

---

Are you holding onto a reference to the timer?

This might be useful for debugging. If you have a property called makeTargetTimer, then you could do this:

NSTimer * makeTargetTimer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(createTargets) userInfo:nil repeats:YES];
self.makeTargetTimer = makeTargetTimer // Save to a property for later use (or just use an iVar)

The only way to stop a re-occurring timer is to invalidate it. Therefore you could check to see if its been invalidated.

BOOL isInvalidated = [self.makeTargetTimer isValid];

Also you might want to do this in your dealloc method anyway:

- (void) dealloc {
    [_makeTargetTimer invalidate];  // Stops the timer from firing (Assumes ARC)
}

---

Are you scrolling when the even should be received?

If you want the timer to be fired while scrolling then you need to use NSRunLoopCommonModes. There is a excellent expiation in this question.

 [[NSRunLoop currentRunLoop] addTimer:makeTargetTimer forMode:NSRunLoopCommonModes]; 

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What is your implementation of createTargets like?

• Have you put NSLog statements on the body of this method. Are you certain its not being called?