Question

override func viewDidDisappear(_ animated: Bool) {
        tableView.visibleCells.forEach {
            if let cell = $0 as? PostsWithVideoCustom , let player = cell.player {
                player.pause()
                cell.player = nil
            }
        }
    }

我在viewDidDisappear上使用了此代码，通常没问题。

但是，如果我在performSegue上viewWillAppear

override func viewWillAppear(_ animated: Bool) {
        if userDefaults.string(forKey: "goToEvent") != nil {
            performSegue(withIdentifier: "postToEvent", sender: self)
        }
       }

我在第tableView.visibleCells.forEach行上崩溃了

如何处理此崩溃以及可能导致什么原因？

更新

此崩溃仅在应用被杀死后启动时发生，而从后台唤醒时则不会发生

崩溃

Crashed: com.apple.main-thread
0  APP                        0x104521cd4 specialized Posts.viewDidDisappear(_:) (Posts.swift:2127)
1  APP                        0x104519864 @objc Posts.viewWillAppear(_:) + 4334082148
2  UIKitCore                      0x247561684 -[UIViewController _setViewAppearState:isAnimating:] + 488
3  UIKitCore                      0x247562008 -[UIViewController __viewDidDisappear:] + 144
4  UIKitCore                      0x2474c31d8 -[UINavigationController viewDidDisappear:] + 232
5  UIKit                          0x23b4b5ea8 -[UINavigationControllerAccessibility viewDidDisappear:] + 40
6  UIKitCore                      0x247561684 -[UIViewController _setViewAppearState:isAnimating:] + 488
7  UIKitCore                      0x247562008 -[UIViewController __viewDidDisappear:] + 144
8  UIKitCore                      0x247498890 -[UITabBarController viewDidDisappear:] + 100
9  UIKitCore                      0x247561684 -[UIViewController _setViewAppearState:isAnimating:] + 488
10 UIKitCore                      0x247562008 -[UIViewController __viewDidDisappear:] + 144
11 UIKitCore                      0x247564168 __64-[UIViewController viewDidMoveToWindow:shouldAppearOrDisappear:]_block_invoke.1383 + 44
12 UIKitCore                      0x247562764 -[UIViewController _executeAfterAppearanceBlock] + 88
13 UIKitCore                      0x247b10ef8 _runAfterCACommitDeferredBlocks + 564
14 UIKitCore                      0x247aff93c _cleanUpAfterCAFlushAndRunDeferredBlocks + 352
15 UIKitCore                      0x247b1e5a8 __34-[UIApplication _firstCommitBlock]_block_invoke_2 + 136
16 CoreFoundation                 0x21b29ee68 __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 20
17 CoreFoundation                 0x21b29e76c __CFRunLoopDoBlocks + 272
18 CoreFoundation                 0x21b2997d0 __CFRunLoopRun + 1024
19 CoreFoundation                 0x21b2990b0 CFRunLoopRunSpecific + 436
20 GraphicsServices               0x21d49979c GSEventRunModal + 104
21 UIKitCore                      0x247b05978 UIApplicationMain + 212
22 APP                        0x1044f8504 main (InboxInterests.swift:22)
23 libdyld.dylib                  0x21ad5e8e0 start + 4

Answer 1

我通过添加

解决了这个问题

if tableView != nil {
        }

这是一个非常简单的修复程序。但是我认为iOS应该首先自己管理。

Answer 2

在viewWillAppear之后放置一些延迟，然后按顺序。在这里，该怎么做：

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated);
    DispatchQueue.main.asyncAfter(deadline: .now()+0.3) {
        if userDefaults.string(forKey: "goToEvent") != nil {
            performSegue(withIdentifier: "postToEvent", sender: self)
        }
    }
}

另一件事：在覆盖任何方法时，请不要忘记调用超级方法，否则有100％的错误行为机会。如果您了解方法重载，那么您一定知道这一点。

tableview visibleCells导致崩溃

2 个答案: