Swift - 从另一个函数访问 UIView 的实例

Question

在我的项目中，用户可以像这样创建UIView（“CustomWishlistView”）：

func createCustomWishlistView() -> CustomWishlistView {
    let v = CustomWishlistView()
    v.translatesAutoresizingMaskIntoConstraints = false
    v.backgroundColor = .darkGray
    v.layer.cornerRadius = 30
    return v
}

@IBAction func createListButtonTapped(_ sender: Any) {


    // "Liste erstellen" button was tapped
    self.appDidEnterBackgroundHandler()

    if let txt = listNameTextfield.text {

        self.newListTextfield.resignFirstResponder()

        // append user-entered text to the data array
        self.theData.append(txt)
        self.imageData.append(self.image!)

        let theCustomWishlistView = createCustomWishlistView()

        self.view.addSubview(theCustomWishlistView)
        // constrain CustomWishlistView
        theCustomWishlistView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 120.0).isActive = true
        theCustomWishlistView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 0).isActive = true
        theCustomWishlistView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor, constant: 30.0).isActive = true
        theCustomWishlistView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: -30.0).isActive = true
        theCustomWishlistView.wishlistImage.image = self.image
        theCustomWishlistView.wishlistLabel.text = txt
        theCustomWishlistView.transform = CGAffineTransform(translationX: 0, y: 1000)

        self.view.bringSubviewToFront(containerView)


        // reload the collection view
        theCollectionView.reloadData()
        theCollectionView.performBatchUpdates(nil, completion: {
            (result) in
            // scroll to make newly added row visible (if needed)
            let i = self.theCollectionView.numberOfItems(inSection: 0) - 1
            let idx = IndexPath(item: i, section: 0)
            self.theCollectionView.scrollToItem(at: idx, at: .bottom, animated: true)

            // close (hide) the "New List" view
            self.closeButtonTappedNewList(nil)
        })
    }
}

我 transform 那个 view 所以一开始它是不可见的。它应该在用户单击UICollectionView 内的cell 后出现。我的代码（在cellForItemAt 内）如下所示：

    if indexPath.item <= theData.count {
           let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ContentCell", for: indexPath) as! ContentCell

            cell.testLabel.text = theData[indexPath.item - 1]

            cell.buttonView.setImage(imageData[indexPath.item - 1], for: .normal)

        cell.customWishlistTapCallback = {
            // let CustomWishlistView appear
//            UIView.animate(withDuration: 0.3, delay: 0, options: .curveEaseIn, animations: {
//                theCustomWishlistView.transform = CGAffineTransform(translationX: 0, y: 0)
//            })
            // let welcomeText disappear
            UIView.animate(withDuration: 0.2, delay: 0, options: .curveEaseOut, animations: {
                self.welcomeTextLabel.transform = CGAffineTransform(translationX: 0, y: 0)
            })
        }
           return cell
       }

我的问题是我不能让我的customWishlistView 出现，因为我无法访问它。有没有办法解决这个问题？ :)

Answer 1

您需要将theCustomWishlistView 设为如下实例变量。您没有显示整个类代码，所以我的解决方案是尽可能完整的，而无需查看您的其余代码

class CustomViewController: UIViewController, UICollectionViewDataSource {

    var theCustomWishlistView: UIView?

    func createCustomWishlistView() -> CustomWishlistView {
        let v = CustomWishlistView()
        v.translatesAutoresizingMaskIntoConstraints = false
        v.backgroundColor = .darkGray
        v.layer.cornerRadius = 30
        return v
    }

    @IBAction func createListButtonTapped(_ sender: Any) {

        // "Liste erstellen" button was tapped
        self.appDidEnterBackgroundHandler()

        if let txt = listNameTextfield.text {

            self.newListTextfield.resignFirstResponder()

            // append user-entered text to the data array
            self.theData.append(txt)
            self.imageData.append(self.image!)

            let wishlistView = createCustomWishlistView()

            self.view.addSubview(wishlistView)
            // constrain wishlistView
            wishlistView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 120.0).isActive = true
            wishlistView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 0).isActive = true
            wishlistView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor, constant: 30.0).isActive = true
            wishlistView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: -30.0).isActive = true
            wishlistView.wishlistImage.image = self.image
            wishlistView.wishlistLabel.text = txt
            wishlistView.transform = CGAffineTransform(translationX: 0, y: 1000)

            // retain wishlist view in instance variable
            self.theCustomWishlistView = wishlistView
            self.view.bringSubviewToFront(containerView)

            // reload the collection view
            theCollectionView.reloadData()
            theCollectionView.performBatchUpdates(nil, completion: {
                (result) in
                // scroll to make newly added row visible (if needed)
                guard let i = self.theCollectionView.numberOfItems(inSection: 0) else { return }
                let idx = IndexPath(item: i - 1, section: 0)
                self.theCollectionView.scrollToItem(at: idx, at: .bottom, animated: true)
                // close (hide) the "New List" view
                self.closeButtonTappedNewList(nil)
            })

        }
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return theData.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

       let _cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ContentCell", for: indexPath)

        guard let cell = _cell as? ContentCell else { return _cell }

        cell.testLabel.text = theData[indexPath.item - 1]

        cell.buttonView.setImage(imageData[indexPath.item - 1], for: .normal)

        cell.customWishlistTapCallback = {
            // let CustomWishlistView appear
            UIView.animate(withDuration: 0.3, delay: 0, options: .curveEaseIn, animations: {
                self.theCustomWishlistView?.transform = CGAffineTransform(translationX: 0, y: 0)
            })
            // let welcomeText disappear
            UIView.animate(withDuration: 0.2, delay: 0, options: .curveEaseOut, animations: {
                self.welcomeTextLabel.transform = CGAffineTransform(translationX: 0, y: 0)
            })
        }
       return cell
   }

}