集合视图内容未显示在视图中
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【中文标题】集合视图内容未显示在视图中【英文标题】：Collection view content not showing in view 【发布时间】：2020-01-17 10:34:40 【问题描述】：我不知道为什么会发生这种情况，我有一个不同的 Xcode 项目，它具有完全相同的集合视图，只是为了测试并制作它，我已经完成了它，它在那个项目中运行良好。然后我将所有代码和项目移到我的主 Xcode 项目中，当我播放应用程序时，集合视图没有显示在我的视图控制器中。
如何调试集合视图？这两个：playerCollect?.cellForItem(at: path) 和 playerCollect.indexPathForItem(at: p) 如果这是个问题，都返回 nil？我不知道。一旦我将它转移到我的主要项目中，我可能还没有将所有东西重新连接在一起，但是你又是如何找到它的呢？这是包含 UICollectionView 的 viewController 的完整代码：
import UIKit
import AVKit
import Firebase
import MMPlayerView
class HomeViewController: UIViewController
var offsetObservation: NSKeyValueObservation?
lazy var mmPlayerLayer: MMPlayerLayer =
let l = MMPlayerLayer()
l.cacheType = .memory(count: 5)
l.coverFitType = .fitToPlayerView
l.videoGravity = AVLayerVideoGravity.resizeAspect
l.replace(cover: CoverA.instantiateFromNib())
l.repeatWhenEnd = true
return l
()
@IBOutlet weak var playerCollect: UICollectionView!
override func viewDidLoad()
super.viewDidLoad()
// remove previous download fails file
MMPlayerDownloader.cleanTmpFile()
self.navigationController?.mmPlayerTransition.push.pass(setting: (_) in
)
offsetObservation = playerCollect.observe(\.contentOffset, options: [.new]) [weak self] (_, value) in
guard let self = self, self.presentedViewController == nil else return
NSObject.cancelPreviousPerformRequests(withTarget: self)
self.perform(#selector(self.startLoading), with: nil, afterDelay: 0.2)
playerCollect.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 200, right:0)
DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) [weak self] in
self?.updateByContentOffset()
self?.startLoading()
mmPlayerLayer.getStatusBlock [weak self] (status) in
switch status
case .failed(let err):
let alert = UIAlertController(title: "err", message: err.description, preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
self?.present(alert, animated: true, completion: nil)
case .ready:
print("Ready to Play")
case .playing:
print("Playing")
case .pause:
print("Pause")
case .end:
print("End")
default: break
mmPlayerLayer.getOrientationChange (status) in
print("Player OrientationChange \(status)")
deinit
offsetObservation?.invalidate()
offsetObservation = nil
print("ViewController deinit")
@IBAction func profileButtonTap(_ sender: Any)
let uid = (Auth.auth().currentUser?.uid)!
let Splash = SpalshScreenViewController()
Splash.GetProfilePicture(uid: uid)
Splash.GetUsername(uid: uid)
Splash.GetName(uid: uid)
Splash.GetClipsNumber(uid: uid)
Splash.GetFollowersNumber(uid: uid)
Splash.GetFollowingsNumber(uid: uid)
performSegue(withIdentifier: "showProfile", sender: nil)
extension HomeViewController: MMPlayerFromProtocol
func backReplaceSuperView(original: UIView?) -> UIView?
guard let path = self.findCurrentPath(),
let cell = self.findCurrentCell(path: path) as? PlayerCell else
return original
return cell.imgView
// add layer to temp view and pass to another controller
var passPlayer: MMPlayerLayer
return self.mmPlayerLayer
func transitionWillStart()
// show cell.image
func transitionCompleted()
self.updateByContentOffset()
self.startLoading()
extension HomeViewController: UICollectionViewDelegateFlowLayout
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
let m = min(UIScreen.main.bounds.size.width, UIScreen.main.bounds.size.height)
return CGSize(width: m, height: m*0.75)
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath)
DispatchQueue.main.async [unowned self] in
if self.presentedViewController != nil || self.mmPlayerLayer.isShrink == true
//self.playerCollect.scrollToItem(at: indexPath, at: .centeredVertically, animated: true)
//self.updateDetail(at: indexPath)
else
self.presentDetail(at: indexPath)
fileprivate func updateByContentOffset()
if mmPlayerLayer.isShrink
return
if let path = findCurrentPath(),
self.presentedViewController == nil
self.updateCell(at: path)
//Demo SubTitle
if path.row == 0, self.mmPlayerLayer.subtitleSetting.subtitleType == nil
let subtitleStr = Bundle.main.path(forResource: "srtDemo", ofType: "srt")!
if let str = try? String.init(contentsOfFile: subtitleStr)
self.mmPlayerLayer.subtitleSetting.subtitleType = .srt(info: str)
self.mmPlayerLayer.subtitleSetting.defaultTextColor = .red
self.mmPlayerLayer.subtitleSetting.defaultFont = UIFont.boldSystemFont(ofSize: 20)
fileprivate func presentDetail(at indexPath: IndexPath)
self.updateCell(at: indexPath)
mmPlayerLayer.resume()
if let vc = UIStoryboard.init(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "DetailViewController") as? DetailViewController
vc.data = DemoSource.shared.demoData[indexPath.row]
self.present(vc, animated: true, completion: nil)
fileprivate func updateCell(at indexPath: IndexPath)
if let cell = playerCollect.cellForItem(at: indexPath) as? PlayerCell, let playURL = cell.data?.play_Url
// this thumb use when transition start and your video dosent start
mmPlayerLayer.thumbImageView.image = cell.imgView.image
// set video where to play
mmPlayerLayer.playView = cell.imgView
mmPlayerLayer.set(url: playURL)
@objc fileprivate func startLoading()
self.updateByContentOffset()
if self.presentedViewController != nil
return
// start loading video
mmPlayerLayer.resume()
private func findCurrentPath() -> IndexPath?
let p = CGPoint(x: playerCollect.contentOffset.x + playerCollect.frame.width/2, y: playerCollect.frame.height/2)
print(playerCollect.indexPathForItem(at: p))
return playerCollect.indexPathForItem(at: p)
private func findCurrentCell(path: IndexPath) -> UICollectionViewCell?
print(playerCollect?.cellForItem(at: path))
return playerCollect?.cellForItem(at: path)
extension HomeViewController: UICollectionViewDataSource
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
return DemoSource.shared.demoData.count
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "PlayerCell", for: indexPath) as? PlayerCell
cell.data = DemoSource.shared.demoData[indexPath.row]
return cell
return UICollectionViewCell()
【问题讨论】：
检查您的UICollectionView 代表和数据源？你有没有从情节提要中连接它？
@HardikS 我该怎么做才能从 swift 文件中做到这一点？
【参考方案1】：
您是否在此视图控制器中提供了集合视图的委托和数据源？
self.playerCollect.delegate = self
self.playerCollect.dataSource = self
并添加：
self.playerCollect.reloadData()
【讨论】：
我该怎么做才能从 swift 文件中做到这一点？ 在 ViewDidLoad ： playerCollect.dataSource = self 和 playerCollect.delegate = self 和 playerCollect.reloadData() 你的类应该是： class HomeViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource 这很奇怪，我之前的项目不需要设置两个就可以了，我猜这只是一个简单的连接？ 我不应该在课堂上这样做，因为我有扩展来这样做【参考方案2】：如下更新您的代码。
class HomeViewController: UIViewController
override func viewDidLoad()
super.viewDidLoad()
// Do any additional setup after loading the view.
self.playerCollect.delegate = self
self.playerCollect.dataSource = self
extension HomeViewController: UICollectionViewDataSource, UICollectionViewDataSource
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
return DemoSource.shared.demoData.count
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "PlayerCell", for: indexPath) as? PlayerCell
cell.data = DemoSource.shared.demoData[indexPath.row]
return cell
return UICollectionViewCell()
【讨论】：
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