ios - 运行此代码时如何以及为何会出现信号 SIGABRT？

Question

当我运行我的应用程序时， View Controller 中会调用一个函数，当发生这种情况时，我会收到信号 SIGABRT。

如何解决这个问题？

功能:

func setRootViewController()
{
    if Auth.auth().currentUser != nil
    {
        let tabVC = storyboard?.instantiateViewController(withIdentifier: "TabVC") as! TestViewController
        view.window?.rootViewController = tabVC
        view.window?.makeKeyAndVisible()
    }
    else
    {
        let welcomeVC = storyboard?.instantiateViewController(withIdentifier: Constants.Storyboard.welcomeVC) as! ViewController
        view.window?.rootViewController = welcomeVC
        view.window?.makeKeyAndVisible()
    }
}

当它崩溃时，我会在控制台区域看到这个:

21 CoreFoundation 0x00007fff23ac4241 CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 17 22 CoreFoundation 0x00007fff23ac416c __CFRunLoopDoSource0 + 76 23 CoreFoundation 0x00007fff23ac3944 __CFRunLoopDoSources0 + 180 24 CoreFoundation
0x00007fff23abe64f __CFRunLoopRun + 1263 25 CoreFoundation
0x00007fff23abde36 CFRunLoopRunSpecific + 438 26 GraphicsServices
0x00007fff37f64bb0 GSEventRunModal + 65 27 UIKitCore
0x00007fff46d562a3 UIApplicationMain + 1621 28 Do It !
0x000000010f1b654b main + 75 29 libdyld.dylib
0x00007fff51175cf5 start + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException (lldb)

Answer 1

尽量避免强行解开。试试这个:

func setRootViewController() {
    if Auth.auth().currentUser != nil {
        if let tabVC = storyboard?.instantiateViewController(withIdentifier: "TabVC") as? TestViewController {
            view.window?.rootViewController = tabVC
            view.window?.makeKeyAndVisible()
        } else {
            print("TabVC doesn't exist or is not a TestViewController")
        }
    } else {
        let welcomeVC = storyboard?.instantiateViewController(withIdentifier: Constants.Storyboard.welcomeVC)
        // you don't need to cast welcomeVC to a ViewController. 
        view.window?.rootViewController = welcomeVC
        view.window?.makeKeyAndVisible()
    }
}

如果这有帮助或者您有任何后续问题，请告诉我。