Memory leak on `initWithNibName`

Question

I'm having an issue with a memory leak. In Instruments, I'm getting a memory leak on this line:

VDLPlaybackViewController *videoController = [[VDLPlaybackViewController alloc] initWithNibName:@"VDLPlaybackView" bundle:nil];

I'm not sure what could be the issue on this. Here is the header file for VDLPlaybackViewController.h :

@protocol VDLPlaybackViewControllerDelegate <NSObject>
@required
-(void)playerShouldClose;
@end

@interface VDLPlaybackViewController : UIViewController <UIDocumentInteractionControllerDelegate>


@property (nonatomic, strong) id<VDLPlaybackViewControllerDelegate> delegate;

// content file stuff.
@property (nonatomic, strong) File *file;
@property (nonatomic, strong) NSNumber *contentID;
@property (nonatomic, strong) NSURL *fileURL;
@property (nonatomic, strong) NSString *pageTitle;

// layout stuff
@property (strong, nonatomic) IBOutlet NSLayoutConstraint *topTimeViewHeight;
@property (strong, nonatomic) IBOutlet NSLayoutConstraint *bottomControlViewHeight;

@property (nonatomic, strong) IBOutlet UIView *movieView;
@property (nonatomic, strong) IBOutlet UIView *navBarView;
@property (nonatomic, strong) IBOutlet UISlider *positionSlider;
@property (nonatomic, strong) IBOutlet UIButton *timeDisplay;
@property (nonatomic, strong) IBOutlet UIButton *playPauseButton;
@property (nonatomic, strong) IBOutlet UIButton *subtitleSwitcherButton;
@property (nonatomic, strong) IBOutlet UIButton *audioSwitcherButton;
@property (nonatomic, strong) IBOutlet UIButton *screenSizeSwitcherButton;
//@property (nonatomic, strong) IBOutlet UINavigationBar *toolbar;
@property (nonatomic, strong) IBOutlet UIView *controllerPanel;
@property (nonatomic, strong) IBOutlet UISlider *volumeSlider;
@property (nonatomic, strong) IBOutlet MPVolumeView *volumeView;
@property (nonatomic, strong) IBOutlet MPVolumeView *airplayView;

@property (nonatomic, assign) CGRect shareButtonFrame;
@property (nonatomic, strong) MultiFileShareButtonController *shareButtonController;
@property (nonatomic, strong) FavoriteFileButtonView *favoriteButtonController;
@property (nonatomic, strong) UIDocumentInteractionController *interactionController;
@property (nonatomic, assign) BOOL isDestroying;

- (void)setMediaURL:(NSURL*)theURL;

- (IBAction)closePlayback:(id)sender;

- (IBAction)positionSliderDrag:(id)sender;
- (IBAction)positionSliderAction:(id)sender;
- (IBAction)toggleTimeDisplay:(id)sender;

- (IBAction)playandPause:(id)sender;
//- (IBAction)switchAudioTrack:(id)sender;
//- (IBAction)switchSubtitleTrack:(id)sender;
- (IBAction)switchVideoDimensions:(id)sender;

@end

Does anyone know what causes this?

Answer 1

The instrumentation tool tells you that there is a leak on the following line:

VDLPlaybackViewController *videoController = [[VDLPlaybackViewController alloc] initWithNibName:@"VDLPlaybackView" bundle:nil];

It does not mean, that it's just this line which is causing the leak, the tool is telling you that a reference of this variable exists as a leak.

You should look for instances where a strong reference to VDLPlaybackViewController *videoController was passed.. may be as delegates or in completion blocks.

The interface which you have in the question has a little problem. It should be weak instead of strong

@property (nonatomic, weak) id<VDLPlaybackViewControllerDelegate> delegate;

Find more instances like this, where you've passed around VDLPlaybackViewController as a strong reference delegate and you would be able to resolve the problem.

To understand more on why the leak is actually happening. Go through https://cocoacasts.com/what-are-strong-reference-cycles