Question

好的，我仍然是新的协议，但我需要从另一个类调用一个函数（我知道在头类中调用时工作）。

要做到这一点，在Im调用函数的类（它是一个MSMessagesAppViewController）我有：

public protocol MSMessagesAppViewControllerDelegate: class {
    func shrinkHeight(height:CGFloat)
    func growHeight(height: CGFloat)
}

weak var delegate: MSMessagesAppViewControllerDelegate?
delegate?.shrinkHeight(height: 90)

然后我在class HeaderCollectionReusableView: UICollectionReusableView, MSMessagesAppViewControllerDelegate中有实际的功能：

 func shrinkHeight(height:CGFloat)
    {
        print("WORKING!!");  //NOT printed

        UIView.animate(withDuration: 0.7, delay: 0.0, usingSpringWithDamping:
            0.6, initialSpringVelocity: 1.1, options: [], animations: {
                //thing being animated

                self.frame = CGRect(x: 0, y: 0, width: self.bounds.width, height: self.screenSize.height * (height/self.screenSize.height))

                //change out
                    self.squareLogo.isHidden = true
                    self.logoLabel.isHidden = false
        }, completion: { finished in
            //code that runs after the transition is complete here


        })
    }

    func growHeight(height:CGFloat)
    {

它编译但我知道上面的函数没有被调用，因为没有print语句。我在这里做错了什么？

Answer 1

几秒钟前我遇到了同样的问题。我觉得你和我有同样的问题。

在您实现MSMessagesAppViewControllerDelegate的自定义UICollectionView类中，您必须为可重用单元添加委托。

类似的东西：

override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
    if kind == UICollectionElementKindSectionHeader {
        let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "headerCell", for: indexPath) as! YourCustomClassForHeader
        headerView.delegate = self // here was my problem, I just forgot to set the delegate
        return headerView
    } else {
        return UICollectionReusableView()
    }
}

Swift：collectionviewHeader委托不工作？

1 个答案: