ios UICollectionViewCell 子类 init 永远不会运行
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UICollectionViewCell subclass init never run
提问by Fogmeister
I have added a collection view in viewDidLoad like this...
我在 viewDidLoad 中添加了一个集合视图，如下所示...
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...
我有一个名为 CameraCell 的 UICollectionViewCell 子类，它的初始化是这样的......
- (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?
但是当我运行应用程序时，集合视图就在那里，我可以滚动它但看不到任何单元格。我在单元格的 init 中添加了一个断点，它永远不会被调用。还有另一种方法我必须覆盖吗？
EDIT
编辑
When I log the cell in cellForItemAtIndexPath...
当我在 cellForItemAtIndexPath 中记录单元格时...
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
CameraCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CameraCellReuseIdentifier forIndexPath:indexPath];
NSLog(@"%@", cell);
return cell;
}
It displays the correct class...
它显示正确的类...
<CameraCell: 0x1f07ba30; baseClass = UICollectionViewCell; frame = (0 20; 320 280); layer = <CALayer: 0x1f07bb40>>
回答by Alejandro
The method you need to implement is - (instancetype)initWithFrame:(CGRect)rect
你需要实现的方法是 - (instancetype)initWithFrame:(CGRect)rect
回答by Archit Baweja
I recently tried this in the iOS7 SDK, and I had to override initWithCoderbecause initWithFramewas never called.
我最近在 iOS7 SDK 中尝试了这个，我不得不重写，initWithCoder因为initWithFrame从来没有被调用过。
回答by Barlow Tucker
If the cell is loaded from a StoryBoard then you will want to override the initializers like this:
如果单元格是从 StoryBoard 加载的，那么您将需要像这样覆盖初始值设定项：
Swift
迅速
override init?(coder aDecoder: NSCoder) {
super.init(coder:aDecoder)
//You Code here
}
Objective-C
目标-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:
如果您从笔尖加载，那么您将需要像这样覆盖初始值设定项：
Swift
迅速
override init(frame: CGRect) {
super.init(frame:frame)
//You Code here
}
Objective-C
目标-C
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
//You code here
}
回答by Jakehao
In my case, when I am using [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, 10, 10) collectionViewLayout:flowLayout]to programatically instantiate a collectionView, initWithFramenever get called, but initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layoutdid.
就我而言，当我使用[[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, 10, 10) collectionViewLayout:flowLayout]以编程方式实例化 collectionView 时，initWithFrame永远不会被调用，但initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout确实如此。
