Question

在我的swift应用中，我创建了代表UICollectionViewController的课程。另外，我还有其他类负责处理'UICollectionReusableView`。

所以在第一堂课我有一个方法：

override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {

    let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "Header", for: indexPath) as! UserProfileHeaderCollectionReusableView

并且由于这个 - 在这种方法中 - 我可以访问存储在标题视图中的所有按钮和标签，例如：

headerView.followButton.isHidden = false

headerView.followButton.addGestureRecognizer(
           UITapGestureRecognizer(target: self, action: #selector(followThisUser)))

稍后，我有一个方法followThisUser：

@objc private func followThisUser(tapGestureRecognizer: UITapGestureRecognizer) {

    if (!doIFollow) {

        followUser(userId)
    } else {
        unfollowUser(userId)
    }
}

并基于标志doIFollow我正在执行特定方法。

我想在用户按下按钮时给予用户反馈，并在按下按钮后立即更改颜色。我试图通过添加：

来访问此按钮

    let tapLocation = tapGestureRecognizer.location(in: self.userProfileCollectionView)

    let indexPath : NSIndexPath = self.userProfileCollectionView.indexPathForItem(at: tapLocation)! as NSIndexPath

到followThisUser方法，但它会抛出错误：

fatal error: unexpectedly found nil while unwrapping an Optional value

如何访问followButton呢？

Answer 1

您可以执行的操作，因为您在按钮上设置了UITapGestureRecognizer - 从处理程序方法中的手势识别器获取原始UIView。像这样将按钮背景颜色变为橙色：

@objc private func buttonTap(tapGestureRecognizer: UITapGestureRecognizer) {

    // Get the view that the gesture is attached to
    let button = tapGestureRecognizer.view

    // Change the view's background color
    button?.backgroundColor = UIColor.orange

}

现在，如果您的原始按钮是UIButton，并且您需要使用UIButton类的某些特殊属性，则可以将视图转换为UIButton

@objc private func buttonTap(tapGestureRecognizer: UITapGestureRecognizer) {

    // Get the view that the gesture is attached to
    let button = tapGestureRecognizer.view as! UIButton

    // Change the UIButton's title label text color
    button.setTitleColor(UIColor.orange, for: .normal)

}

Answer 2

试试这个

var tapGesture : UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: "processTapGesture:")
        tapGesture.numberOfTapsRequired = 1
        collectionView.addGestureRecognizer(tapGesture)

处理手势

func processTapGesture (sender: UITapGestureRecognizer)
    {
        if sender.state == UIGestureRecognizerState.Ended
        {
            var point:CGPoint = sender.locationInView(collectionView)
            var indelPath:NSIndexPath =collectionView.indexPathForItemAtPoint(point)
            if indexPath
            {
                print("image taped")
            }
            else
            {
               //Do Some Other Stuff Here That Isnt Related;
            }
        }
    }

tapGestureRecognizer.location在UICollectionView中带来nil

2 个答案: