UIPresentationController 崩溃仅指向 AppDelegate

截图：

I am getting a lot of these crashes but the problem is I'm just being pointed to my appDelegate first line. I've no idea where to look for the issue. Any ideas where I could start to investigate from the following crash report?

Crashed: com.apple.main-thread
0  UIKit                          0x18d005640 __56-

[UIPresentationController runTransitionForCurrentState]_block_invoke + 460
1  UIKit                          0x18cf27aa8 _runAfterCACommitDeferredBlocks + 292
2  UIKit                          0x18cf1ae5c _cleanUpAfterCAFlushAndRunDeferredBlocks + 288
3  UIKit                          0x18ccac464 _afterCACommitHandler + 132
4  CoreFoundation                 0x1836a6cdc __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 32
5  CoreFoundation                 0x1836a4694 __CFRunLoopDoObservers + 412
6  CoreFoundation                 0x1836a4c50 __CFRunLoopRun + 1292
7  CoreFoundation                 0x1835c4c58 CFRunLoopRunSpecific + 436
8  GraphicsServices               0x185470f84 GSEventRunModal + 100
9  UIKit                          0x18cd1d5c4 UIApplicationMain + 236
10 AppName                        0x100ae3ca4 main (AppDelegate.swift:23)
11 libdyld.dylib                  0x1830e456c start + 4

Update:

基于以下几点：

应用程序在 runTransitionForCurrentState 上崩溃，但不知道为什么 https://stackoverflow.com/questions/39530125/app-crashing-on-runtransitionforcurrentstate-but-no-clue-as-to-why

我正在寻找潜在的原因，并对以下代码感到好奇。

我有以下功能，用于在执行同步过程时呈现带有活动指示器的视图。

public func displayActivityAlertWithCompletion(_ title: String, ViewController: UIViewController, completionHandler: @escaping ()->())
{
    let pending = UIAlertController(title: "\n\n\n"+title, message: nil, preferredStyle: .alert)
    //create an activity indicator
    let indicator = UIActivityIndicatorView(frame: pending.view.bounds)
    indicator.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    indicator.color = UIColor(rgba: Palette.loadingColour)
    //add the activity indicator as a subview of the alert controller's view
    pending.view.addSubview(indicator)
    indicator.isUserInteractionEnabled = false
    // required otherwise if there buttons in the UIAlertController you will not be able to press them
    indicator.startAnimating()


    ViewController.present(pending, animated: true, completion: completionHandler)
}

然后我像这样使用这个函数：

displayActivityAlertWithCompletion("Pushing Data", ViewController: self){_ in
    Helper_class.doSync(_cleanSync: false){
        //sync is complete
        Prefs.is_Syncing = false
        DispatchQueue.main.async {
            //dismiss my view with activity alert
            self.dismiss(animated: true){
                //dismiss my viewcontroller
                Toast(text: "Upload sync completed").show()
                self.dismiss(animated: true, completion: nil)
            }
        }
    }
}

这会是 UIKit 问题的潜在原因吗？

按照以下步骤，你就可以做到： 1. 打开导航器； 2.切换到断点导航器； 3、点击左下角“+”按钮； 4. 弹出窗口时，单击“异常断点”。

然后再次运行您的项目，它将在确切的位置中断。