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POProblems invalidating & re-creating NSTimer(s)
 

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  1. POProblems invalidating & re-creating NSTimer(s)
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    <p>I'm having problems starting &amp; stopping NSTimers. The docs say that a timer is stopped by [timer invalidate];</p> <p>I have a timer object declared as such</p> <pre><code>.h NSTimer *incrementTimer; @property (nonatomic, retain) NSTimer *incrementTimer; .m @synthesize incrementTimer; -(void)dealloc { [incrementTimer release]; [super dealloc]; } </code></pre> <p>-The usual.</p> <p>When it's needed, my method does the following:</p> <pre><code>-(void)setGenCount { if(!condition1 &amp;&amp; condition2) { incrementTimer = [NSTimer scheduledTimerWithTimeInterval: 2.0 target: self selector:@selector(incrementBatteryVoltage:) userInfo: nil repeats: YES]; } } </code></pre> <p>Everything above works fine. However, once that timer does it's job, I want it to invalidate itself. I invalidate the timer because there is an equal decrement method that could be called and would fight against the incrementTimer if it was still active. (Previously, I noticed that my two timers, if active, were acting on the same ivar by increasing &amp; decreasing the value (a sort of fight)... without crashing) The selector called works as follows: </p> <pre><code>-(void)incrementBatteryVoltage:(NSTimer *)timer { if(battVoltage &lt; 24.0) { generatorDisplay.battVoltage += 0.1; } if(battery1Voltage == 24.0) { [timer invalidate]; } } </code></pre> <p>I have an equal method that Decrements the battery count. (previously mentioned)<br> Due to my program design: the interface simulates a voltage display. When the "machine" is turned off, I want all the timers invalidated, regardless of what any voltage value is. I'm doing this by checking to see if the timer is valid.</p> <pre><code>-(void)deEnergizeDisplays { if([decrementTimer isValid]) { [decrementTimer invalidate]; decrementTimer = nil; } if([incrementTimer isValid]) { [incrementTimer invalidate]; incrementTimer = nil; } </code></pre> <p>I'm getting numerous "BAD_ACCESS" crashes. The erroneous line call is always pointing toward my [timer isValid] call. It seems that if the timer is invalidated... the pointer doesn't exist either. I know that the [timer invalidate] message disables the timer and then it is removed from the run loop and then it is released. And my understanding is: it is an autoreleased object per it's naming covention.</p> <p>My thought are: If I'm sending a retain message, shouldn't the reference still exist? I've tried several combinations, taking away:</p> <pre><code>timer = nil; </code></pre> <p>or even instead of: </p> <pre><code>if([timer isValid]) </code></pre> <p>I tried :</p> <pre><code>if([timer != nil]) </code></pre> <p>and: </p> <pre><code>if(timer) </code></pre> <p>I always get the same crash. Thanks for any help on starting &amp; stopping NSTimers.</p>
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    1. USsamfu_1
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      1. USMike Reedell
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    1. COUnrelated to your crash, I think, but you probably don't want to be checking floating point numbers for explicit equality.
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      1. USCarl Norum
    2. COHow would you accomplish this task? Check for (battVoltage > 24)?
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    3. COThat's a better way to go, yeah.
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      1. USCarl Norum
 

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