Objective-C self.delegate is null after being set

Question

I've setup a pretty simple delegate, for a UIView. However, when I try to do:

if ([self.delegate respondsToSelector:@selector(selectedPlayTrailer:)]){
    [self.delegate selectedPlayTrailer:self];
}

My self.delegate is null. I checked the setter that the class being set as the delegate is right by:

- (void)setDelegate:(id<MyViewDelegate>)delegateClass
{
    // Whether I overwrite this method or not, it's still null.
    NSLog(@"%@", delegate);
    _delegate = delegateClass;
}

And it's correct. But by the time it's called in my IBAction - it's null.

EDIT: To clarify, I only dropped this in to see what was being passed in. If I don't overwrite this method, it's still null.

My code:

MyView.h

#import <UIKit/UIKit.h>

@class MyView;

@protocol MyViewDelegate <NSObject>
@optional
- (void) myDelegateMethod:(MyView *)sender;
@end

@interface MyView : UIView

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

- (IBAction)myButton:(id)sender;

@end

MyView.m

@implementation MyView

@synthesize delegate;

- (id)init
{
    if (!(self = [super init])) return nil;

    NSArray *subviewArray = [[NSBundle mainBundle] loadNibNamed:@"MyView"
                                                          owner:self
                                                        options:nil];

    return self;
}

- (IBAction)myButton:(id)sender
{
    // NOTE: Here, self.delegate is null
    if ([self.delegate respondsToSelector:@selector(myDelegateMethod:)]){
        [self.delegate myDelegateMethod:self];
    }
}

@end

MyCollectionViewCell.m

#import "MyCollectionViewCell.h"
#import "MyView.h"

@interface MyCollectionViewCell() <MyViewDelegate>
@property (nonatomic, strong) MyView *myView;
@end

@implementation MyCollectionViewCell

@synthesize myView;

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];

    if (self){
        [self setup];
    }

    return self;
}

- (void)setup
{
    self.myView = [MyView new];
    self.myView.frame = CGRectMake(0,0,self.bounds.size.width, self.bounds.size.height);
    self.myView.alpha = 0.0;
    self.myView.layer.cornerRadius = 5.0f;
    self.myView.layer.masksToBounds = YES;
    self.myView.delegate = self;

    [self addSubview:self.myView];
}

// The delegate method
- (void)myDelegateMethod:(MyView *)sender
{
    NSLog(@"This is never called...");
}

@end

Answer 1

To MyCollectionViewCell add this:

- (void)dealloc
{
    NSLog(@"MyCollectionViewCell dealloc called")
}

delegate is a weak reference. So if the instance which is set to the delegate is released, it will become nil. The purpose of the above is to confirm this is happening.

Why would this happen? If nothing is maintaining a strong reference to the MyCollectionViewCell instance, then it will be released.

Ideally, you'd also want to add an NSLog to myButtonPressed:. It would also be beneficial if you NSLog'd the setting of the delegate. So your output could be potentially something like:

Delegate set
MyCollectionViewCell dealloc called <- this would indicate that the delegate becomes nil based on the instance being released
myButtonPressed: hit

This is a working theory, given the amount of info you have provided.

Answer 2

Set the viewcontroller as the delegate of MyView object instead of collection view cell.

In your view controller, inside the datasource method

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView 
                  cellForItemAtIndexPath:(NSIndexPath *)indexPath

do something like this.

cell.myView.delegate = self;

Update

As observed, the problem is in allocating the UIView subclass. Initializing the view as

self.myView = [MyView new];

does not work for some reason. To properly allocate the view, the following approach can be used.

 self.myView = [[[NSBundle mainBundle]
        loadNibNamed:@"MyView"
        owner:self options:nil]
         firstObject];