How to tell if an object has been released

Question

How can I tell if an object has been released?

If the UITableViewCell has been moved out screen, kkcell object will be autoreleased by UITableView.

When the audioPlayer finishes, program calls " [kkcell stopSpeakAmination]", but this causes the program to crash.

- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag{

    [kkcell stopSpeakAmination];
    playing=NO;
}

I also use

if(kkcell)

or

if(kkcell!=nil)

but it still crashes.

Here is some more code that I am using:

//KKMessageCell2.m
....
@property(nonatomic, retain) UIImageView *SenderVoiceNodePlaying;
@property(nonatomic, retain) UIImageView *ReceiverVoiceNodePlaying;
....

-(void)stopSpeakAmination{
    [self.SenderVoiceNodePlaying stopAnimating];
    [self.ReceiverVoiceNodePlaying stopAnimating];
}

-(void)speakAminationOnRight:(UIButton*)btn{

    //rightside
    NSArray *speekImageAry = [[NSArray alloc]initWithObjects:
    [UIImage imageNamed:@"SenderVoiceNodePlaying001"],
    [UIImage imageNamed:@"SenderVoiceNodePlaying002"],
                          [UIImage imageNamed:@"SenderVoiceNodePlaying003"], nil];


    self.SenderVoiceNodePlaying.animationImages = speekImageAry; 
    self.SenderVoiceNodePlaying.animationDuration = 1.0; 
    self.SenderVoiceNodePlaying.animationRepeatCount = 0; 
    [self.SenderVoiceNodePlaying startAnimating];

    NSString *fileName=btn.titleLabel.text;
    fileName=[fileName substringFromIndex:10];
    KKMessageCell2 *cell=(KKMessageCell2*)[btn superview];
    [[NSNotificationCenter defaultCenter]postNotificationName:@"nPlayAmr"
                                    object:nil userInfo:[NSDictionary dictionaryWithObjectsAndKeys:
                                                         fileName,@"fileName",
                                                         cell,@"cell",nil]];
}

//KKMessageCell2.m
....

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
    static NSString *identifier = @"msgCell";
    NSDictionary *dict = [messages objectAtIndex:indexPath.row];
    KKMessageCell2 *cell = [[[KKMessageCell2 alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:identifier] autorelease];
    cell.selectionStyle = UITableViewCellSelectionStyleNone;
    [cell setCellView:dict andMy_avatar_url:self.my_avatar_url];
    [cell.avatarLeftImageButton addTarget:self action:@selector(pushToUserDetail:) forControlEvents:UIControlEventTouchUpInside];
    [cell.avatarRightImageButton addTarget:self action:@selector(pushToUserDetail:) forControlEvents:UIControlEventTouchUpInside];
    [cell.chatphoto addTarget:self action:@selector(photoClick:) forControlEvents:UIControlEventTouchUpInside];
    return cell;

}

- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag{

    [kkcell stopSpeakAmination];
    playing=NO;
}

Answer 1

Convert your project to ARC. It is much easier and automated than you would think. I've converted about 3 real life projects that were quite large in mid-development and never had any issues (put aside one hour to do it, you probably won't need that much time and its definitely worth it)

in Xcode, select edit->refactor->convert to Objective-C ARC

You can also find tutorials online but its pretty straight forward overall.

Answer 2

Your program crashes most likely because the object was indeed fully released but that doesn't mean that kkcell would be set to nil , hence your checks failing, kkcell is "dangling".

To answer your specific question, one way to test for release is to override dealloc as in

-(void)dealloc
{
    NSLog(@"deallocated");
    [super dealloc];
}

This may help you troubleshoot by telling you exactly when the final release happens.