Question

I want a timer class that can post messages to a delegate when there are 1/2/3 seconds to go.

My test target consistently crashes.

• iOS logic unit test target.
• Tests class that times a duration using a repeating NSTimer
• One test with no asserts. The test passes, but then the target crashes with:

/Developer/Tools/RunPlatformUnitTests.include: line 415: 770 Bus error "${THIN_TEST_RIG}" "${OTHER_TEST_FLAGS}" "${TEST_BUNDLE_PATH}"

It seems to me that it’s some kind of memory allocation error, but I can’t figure out what I’m missing. The problem is associated with the stop timer routine somehow. It’s only when the timer runs out that the target crashes.

Things I’ve tried

• Build and Analyze – no errors reported
• Remove -framework and UIKit from the linker flags
• Removing dealloc – this has no effect

Test Code

-(void)testGivenThreeSecondDurationAtOneSecondDelegateShouldBeToldToShowGreenCard {
    JGTimerController *timer = [JGTimerController timerWithDurationValue:1 delegate:nil];
    [timer startTimer];

    [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:1.1]];
}

Class Code

@interface JGTimerController : NSObject {
    NSNumber    *duration;
    NSTimer     *timer;
    id <NSObject, JGTimerControllerDelegate> _delegate;
}
@property (nonatomic, retain) NSNumber *duration;
... public methods...
@end


@implementation JGTimerController

@synthesize duration;

+(JGTimerController *)timerWithDurationValue:(NSUInteger)durationValue delegate:(id <JGTimerControllerDelegate>)delegate_ {
    JGTimerController *instance = [[[JGTimerController alloc] initWithDurationValue:durationValue delegate:delegate_] autorelease];
    return instance;
}

-(JGTimerController *)initWithDurationValue:(NSUInteger)durationValue delegate:(id <JGTimerControllerDelegate>)delegate_ {
    self = [super init];
    timer = nil;
    [self setDurationValue:durationValue];
    _delegate = delegate_;
    return self;
}

-(NSUInteger)durationValue {
    NSNumber *result = [self duration];
    return result ? [result intValue] : 0;
}

-(void)setDurationValue:(NSUInteger)value_ {
    [self setDuration:[NSNumber numberWithInt:value_]];
}

-(BOOL)stopTimerAtZeroDuration:(NSTimer *)timer_ {
    if ([self durationValue] == 0) {
        [self stopTimer];
        return YES;
    }
    return NO;
}

-(void)startTimer {
    if ([self stopTimerAtZeroDuration:nil])
        return;

    timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timerDidCountDownByASecond:) userInfo:nil repeats:YES];
}

-(void)stopTimer {
    if ([self durationValue] == 0 && [_delegate conformsToProtocol:@protocol(JGTimerControllerDelegate)])
        [_delegate showRedCard];

    [timer invalidate];
    [timer release];
}

-(BOOL)timerIsRunning {
    return (timer != nil);
}

-(void)timerDidCountDownByASecond:(NSTimer *)timer_ {
    [self setDurationValue:[self durationValue] - 1];
    [self stopTimerAtZeroDuration:timer_];
}

-(void)dealloc {
    [_delegate release];
    [timer release];
    [duration release];
    [super dealloc];
}

@end

Answer 1

Likewise, timer should not be released. NSTimer is like every other NSObject, if you did not alloc, copy or retain, you do not need to release.