内联属性实例化不适用于通用UICollectionViewCell子类 [英] Inline property instantiation not working for generic UICollectionViewCell subclasses

问题描述

如果我定义了UICollectionViewCell子类:

If I define a UICollectionViewCell subclass:

class TestCell<T>: UICollectionViewCell {
  var float: CGFloat? = 3
  var string = "abc"
}

注册:

collectionView.registerClass(TestCell<String>.self, forCellWithReuseIdentifier: "Test")

然后使用它:

collectionView.dequeueReusableCellWithReuseIdentifier("Test", forIndexPath: indexPath) as! TestCell<String>

我注意到应该初始化的属性具有奇怪的行为.

I notice strange behavior with the properties that should have been initialized.

• float ==可选(0.0)
• string =="

为什么会这样，我该如何解决?

Why is this happening and how can I fix it?

这是在Xcode 7.3上

This is on Xcode 7.3

推荐答案

看起来像是与泛型相关的错误.

Looks like this was a bug related to generics.

如果摆脱了通用说明符，变量将按预期进行初始化.

If you get rid of the generic specifier, the variables are initialized as you expect.

如果需要通用说明符，可以通过实例化init方法而不是内联方法的属性来解决此问题:

If you need the generic specifier, you can workaround the issue by instantiating the properties in the init method rather than inline:

class TestCell<T>: UICollectionViewCell {
  override init(frame: CGRect) {
    float = 3
    string = "abc"
    super.init(frame: frame)
  }

  var float: CGFloat?
  var string: String
}

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