UIRefreshControl endRefresh 在启用 Large Title 时跳转

Question

我正在尝试使用 UIRefreshControl，但是当我调用 endRefreshing() 时它会跳转 UINavigationBar。只有当我将 UIRefreshControl 与大标题一起使用时才会出现此问题。看了这里报的一些类似的问题（），我试过拖动结束才刷新，但是还是出现bug。还尝试使用

self.navigationController?.navigationBar.isTranslucent = false 和 self.extendedLayoutIncludesOpaqueBars = true

但是，none在其他问题上找到的解决方案似乎解决了问题，但仍然不顺利。

现场视频：

https://www.youtube.com/watch?v=2BBRnZ444bE

应用委托

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?

    func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
        ) -> Bool {

        let window = UIWindow(frame: UIScreen.main.bounds)
        window.makeKeyAndVisible()
        let nav = UINavigationController()
        nav.title = "My Nav"
        nav.navigationBar.prefersLargeTitles = true
        nav.viewControllers = [ViewController()]
        window.rootViewController = nav

        self.window = window
        return true
    }

}

请注意我使用的是大标题：

        let nav = UINavigationController()
        nav.title = "My Nav"
        nav.navigationBar.prefersLargeTitles = true

ViewController:

import UIKit
import Foundation

final class ViewController: UICollectionViewController {
    let randomHeight = Int.random(in: 100..<300)

    init() {
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .vertical
        layout.estimatedItemSize = CGSize(width: 20, height: 20)
        super.init(collectionViewLayout: layout)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        navigationItem.title = "Try to refresh"

        self.navigationController?.navigationBar.isTranslucent = false
        self.extendedLayoutIncludesOpaqueBars = true

        collectionView.backgroundColor = .white
        registerCells()
        setupRefreshControl()
    }

    private func registerCells() {
        self.collectionView.register(
            Cell.self,
            forCellWithReuseIdentifier: "Cell"
        )
    }

    private func setupRefreshControl() {
        let refreshControl = UIRefreshControl()
        refreshControl.addTarget(
            self,
            action: #selector(refreshControlDidFire),
            for: .valueChanged
        )
        self.collectionView.refreshControl = refreshControl
    }

    @objc private func refreshControlDidFire(_ sender: Any?) {
        if let sender = sender as? UIRefreshControl, sender.isRefreshing {
            refresh()
        }
    }

    override func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
        if collectionView.refreshControl!.isRefreshing {
            refresh()
        }
    }

    private func refresh() {
        if !collectionView.isDragging {
            collectionView.refreshControl!.endRefreshing()
            collectionView.perform(#selector(collectionView.reloadData), with: nil, afterDelay: 0.05)
        }
    }
}

extension ViewController {
    override func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }

    override func collectionView(
        _ collectionView: UICollectionView,
        numberOfItemsInSection section: Int
        ) -> Int {
        return 10
    }

    override func collectionView(_ collectionView: UICollectionView,
                                 cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        guard let cell = collectionView.dequeueReusableCell(
            withReuseIdentifier: "Cell", for: indexPath
            ) as? Cell else {
                return UICollectionViewCell()
        }

        cell.label.text = "Text number \(indexPath.row), with height \(randomHeight)"
        cell.heightAnchorConstraint.constant = CGFloat(randomHeight)
        return cell
    }
}

extension ViewController: UICollectionViewDelegateFlowLayout {

    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets(top: 20, left: 0, bottom: 0, right: 0)
    }
}

final class Cell: UICollectionViewCell {
    private let shadowView = UIView()
    private let containerView = UIView()
    private let content = UIView()
    let label = UILabel()
    var heightAnchorConstraint: NSLayoutConstraint!

    override init(frame: CGRect = .zero) {
        super.init(frame: frame)
        setupViews()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    private func setupViews() {
        insertSubview(shadowView, at: 0)
        addSubview(containerView)
        containerView.addSubview(label)
        containerView.addSubview(content)
        activateConstraints()
    }

    private func activateConstraints() {
        self.translatesAutoresizingMaskIntoConstraints = false
        shadowView.translatesAutoresizingMaskIntoConstraints = false
        containerView.translatesAutoresizingMaskIntoConstraints = false
        label.translatesAutoresizingMaskIntoConstraints = false
        content.translatesAutoresizingMaskIntoConstraints = false

        shadowView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
        shadowView.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
        shadowView.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
        shadowView.bottomAnchor
            .constraint(equalTo: self.bottomAnchor).isActive = true

        containerView.backgroundColor = .white
        containerView.layer.cornerRadius = 14

        containerView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
        containerView.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
        containerView.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
        containerView.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
        let widthAnchorConstraint = containerView.widthAnchor.constraint(equalToConstant: UIScreen.main.bounds.width - 20)
        widthAnchorConstraint.identifier = "Width ContainerView"
        widthAnchorConstraint.priority = .defaultHigh
        widthAnchorConstraint.isActive = true

        label.numberOfLines = 0
        label.textAlignment = .center
        label.centerXAnchor.constraint(equalTo: containerView.centerXAnchor).isActive = true
        label.centerYAnchor.constraint(equalTo: containerView.centerYAnchor).isActive = true
        label.leadingAnchor.constraint(equalTo: containerView.leadingAnchor).isActive = true
        label.trailingAnchor.constraint(equalTo: containerView.trailingAnchor).isActive = true

        content.leadingAnchor.constraint(equalTo: containerView.leadingAnchor, constant: 20).isActive = true
        content.topAnchor.constraint(equalTo: containerView.topAnchor, constant: 10).isActive = true
        content.bottomAnchor.constraint(lessThanOrEqualTo: containerView.bottomAnchor, constant: -10).isActive = true
        heightAnchorConstraint = content.heightAnchor.constraint(greaterThanOrEqualToConstant: 220)
        heightAnchorConstraint.identifier = "Height Content"
        heightAnchorConstraint.priority = .defaultHigh
        heightAnchorConstraint.isActive = true
        content.widthAnchor.constraint(equalToConstant: 40).isActive = true
        content.backgroundColor = .red

    }

    override func layoutSubviews() {
        super.layoutSubviews()
        applyShadow(width: 0.20, height: -0.064)
    }

    private func applyShadow(width: CGFloat, height: CGFloat) {
        let shadowPath = UIBezierPath(roundedRect: shadowView.bounds, cornerRadius: 14.0)
        shadowView.layer.masksToBounds = false
        shadowView.layer.shadowRadius = 8.0
        shadowView.layer.shadowColor = UIColor.black.cgColor
        shadowView.layer.shadowOffset = CGSize(width: width, height: height)
        shadowView.layer.shadowOpacity = 0.3
        shadowView.layer.shadowPath = shadowPath.cgPath
    }
}

Answer 1

所以，我尝试了您的代码，一切正常。

但我运行它在 iPhone 7 - 那里没有大标题。

我认为，这是 largeTitle 的问题。

您可以尝试使用此代码段：

self.navigationController?.navigationBar.prefersLargeTitles = false
self.navigationController?.navigationBar.prefersLargeTitles = true

Answer 2

问题与layout.estimatedItemSize = CGSize(width: 20, height: 20)

有关

当我们使用 AutoLayout 调整单元格大小时，它会产生 UIRefreshControl 和导航栏大标题的错误。因此，如果您使用 layout.estimatedItemSize 且大小等于或大于我们的预期。所以bug不会发生，故障也不会发生。

基本上，问题是当我们调用 updateData 但单元格比我们预期的要大并且 UICollectinView 的每个单元格将调整到更大的大小然后 UICollectionViewController 将故障。

UIRefreshControl endRefresh 在启用 Large Title 时跳转

UIRefreshControl endRefresh jumps when used with Large Title enabled

ios

swift

uicollectionview

uiscrollview

uirefreshcontrol