UICollectionViewCell subclass init never run

Question

I have added a collection view in viewDidLoad like this...

self.collectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, 10, 10) collectionViewLayout:flowLayout];
self.collectionView.delegate = self;
self.collectionView.dataSource = self;
self.collectionView.backgroundColor = [UIColor whiteColor];
[self.collectionView registerClass:[CameraCell class] forCellWithReuseIdentifier:CameraCellReuseIdentifier];
[self.collectionView setTranslatesAutoresizingMaskIntoConstraints:NO];
[self.view addSubview:self.collectionView];

And I have a UICollectionViewCell subclass called CameraCell with an init like this...

- (id)init
{
    self = [super init];
    if (self) {
        // Add customisation here...
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(imageChanged:) name:@"image" object:nil];

        self.contentView.backgroundColor = [UIColor yellowColor];

        self.imageView = [[UIImageView alloc] initWithFrame:CGRectZero];
        self.imageView.contentMode = UIViewContentModeScaleAspectFill;
        self.imageView.clipsToBounds = YES;
        [self.imageView setTranslatesAutoresizingMaskIntoConstraints:NO];
        [self.contentView addSubview:self.imageView];

        NSDictionary *views = NSDictionaryOfVariableBindings(_imageView);

        [self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_imageView]|"
                                                                                 options:0
                                                                                 metrics:nil
                                                                                   views:views]];

        [self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|[_imageView]|"
                                                                                 options:0
                                                                                 metrics:nil
                                                                                   views:views]];
    }
    return self;
}

But when I run the app the collection view is there and I can scroll it but I can't see any cells. I have added a breakpoint in the cell's init and it never gets called. Is there another method I have to override?

EDIT

When I log the cell in cellForItemAtIndexPath...

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    CameraCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CameraCellReuseIdentifier forIndexPath:indexPath];

    NSLog(@"%@", cell);

    return cell;
}

It displays the correct class...

<CameraCell: 0x1f07ba30; baseClass = UICollectionViewCell; frame = (0 20; 320 280); layer = <CALayer: 0x1f07bb40>>

I mean, you are calling initWithFrame instead of init... – rocky May 13 '13 at 22:01 — rocky, May 13 '13 at 22:01

Alejandro · Accepted Answer · 2017-04-14T18:55:20.850

48

The method you need to implement is - (instancetype)initWithFrame:(CGRect)rect

edited Apr 14 '17 at 18:55

answered May 13 '13 at 22:01

Alejandro

3,726
1
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1

OMG I can't believe I did that. Thanks. – Fogmeister May 13 '13 at 22:02
1

But isn't the frame governed by `collectionView` itself—rendering this `initWithFrame` from the `collectionViewCell` useless? – mfaani May 24 '16 at 09:57
3

The frame argument you get is kind of useless, but you will still need to initialize your own properties here. – Alejandro May 24 '16 at 19:14

score 28 · Answer 2 · edited Mar 21 '15 at 23:09

28

I recently tried this in the iOS7 SDK, and I had to override initWithCoder because initWithFrame was never called.

edited Mar 21 '15 at 23:09

Glen Selle

3,966
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answered Sep 19 '13 at 02:03

Archit Baweja

973
7
18

1

Were you loading it from a storyboard or nib? Or all in code? – Fogmeister Sep 19 '13 at 06:40
The cell is loaded from a Storyboard. – Archit Baweja Sep 19 '13 at 17:55
42

^Then that's why. `initWithCoder` is the designated initializer for views built from the storyboard. `initWithFrame` is for views that are built programatically. – Matthew Quiros Jan 21 '14 at 07:42
2

Frequent problem :) I usually put all construction in `init`, and then call it from overridden `initWithFrame` and `initWithCoder`. it makes cell class more universal. Or, when I need to save original initWithCoder behavior, I make another one method `universalInit`, put all my custom code there and call it from all default initializers. Of course, with Swift this trick is no more handy. – Cemen Mar 13 '15 at 10:01

score 24 · Answer 3 · answered Aug 09 '16 at 22:23

If the cell is loaded from a StoryBoard then you will want to override the initializers like this:

Swift

override init?(coder aDecoder: NSCoder) {
  super.init(coder:aDecoder)
  //You Code here
}

Objective-C

- (id)initWithCoder:(NSCoder *)aDecoder {
  self = [super initWithCoder:aDecoder];
  //You code here
}

If you are loading from a nib, then you will want to override the initializers like this:

Swift

override init(frame: CGRect) {
  super.init(frame:frame)
  //You Code here
}

Objective-C

- (id)initWithFrame:(CGRect)frame {
  self = [super initWithFrame:frame];
  //You code here
}

score 2 · Answer 4 · answered Jun 28 '21 at 12:40

I know the question is way old, but personally I was lazy and wanted to copy-paste code from somewhere. Unfortunately, there is no 100% correct solution above so I wrote common pattern (for both IB-based and code-based cells)

    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        commonInit()
    }
    
    override func awakeFromNib() {
        commonInit()
    }
    
    private func commonInit() {
        
    }

score -1 · Answer 5 · answered May 18 '15 at 09:27

In my case, when I am using [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, 10, 10) collectionViewLayout:flowLayout] to programatically instantiate a collectionView, initWithFrame never get called, but initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout did.

score -1 · Answer 6 · answered Sep 28 '22 at 04:15

-1

Swift 5:

required init?(coder aDecoder: NSCoder) {
    super.init(coder:aDecoder)
    // Your code here.
}

answered Sep 28 '22 at 04:15

Joe

3,772
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Any reason for why you downvoted my question? – Fogmeister Sep 29 '22 at 18:53

UICollectionViewCell subclass init never run

6 Answers6