这个错误的困扰了我半天，具体错误如下：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[meetingbot4ios.AppDelegate window]: unrecognized selector sent to instance 0x60000370c0c0'

*** First throw call stack:

(

0   CoreFoundation                      0x00000001804ae0f8 __exceptionPreprocess + 172

1   libobjc.A.dylib                     0x0000000180087db4 objc_exception_throw + 56

2   CoreFoundation                      0x00000001804c2f48 +[NSObject(NSObject) instanceMethodSignatureForSelector:] + 0

3   CoreFoundation                      0x00000001804b2024 ___forwarding___ + 732

4   CoreFoundation                      0x00000001804b456c _CF_forwarding_prep_0 + 92

5   MobileRTC                           0x00000001125bed2c MobileRTC + 16624940

6   CoreFoundation                      0x00000001803de7a8 __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 140

7   CoreFoundation                      0x00000001803de6cc ___CFXRegistrationPost_block_invoke + 84

8   CoreFoundation                      0x00000001803ddbbc _CFXRegistrationPost + 404

9   CoreFoundation                      0x00000001803dd598 _CFXNotificationPost + 688

10  MobileRTC                           0x0000000112792840 MobileRTC + 18540608

11  MobileRTC                           0x0000000113b82624 MobileRTC + 39446052

12  MobileRTC                           0x0000000113b7f7a8 MobileRTC + 39434152

13  MobileRTC                           0x0000000113d0f0b0 MobileRTC + 41070768

14  MobileRTC                           0x0000000113cfc4b0 MobileRTC + 40993968

15  MobileRTC                           0x0000000113cfe520 MobileRTC + 41002272

16  MobileRTC                           0x0000000111675520 MobileRTC + 595232

17  MobileRTC                           0x0000000113cfde1c MobileRTC + 41000476

18  MobileRTC                           0x0000000113b83188 MobileRTC + 39448968

19  MobileRTC                           0x0000000113516a04 MobileRTC + 32713220

20  MobileRTC                           0x00000001116540bc MobileRTC + 458940

21  meetingbot4ios                      0x0000000102d00fe8 $s14meetingbot4ios11AppDelegateC11joinMeeting33_AF24E5846D9D1EA8BDA822FD40DAC3E8LLyyF + 700

22  meetingbot4ios                      0x0000000102d00858 $s14meetingbot4ios11AppDelegateC21onMobileRTCAuthReturnyySo0eF5ErrorVF + 308

23  meetingbot4ios                      0x0000000102d00b28 $s14meetingbot4ios11AppDelegateC21onMobileRTCAuthReturnyySo0eF5ErrorVFTo + 44

24  libdispatch.dylib                   0x00000001030a7ec4 _dispatch_call_block_and_release + 24

25  libdispatch.dylib                   0x00000001030a973c _dispatch_client_callout + 16

26  libdispatch.dylib                   0x00000001030b93f8 _dispatch_main_queue_drain + 1228

27  libdispatch.dylib                   0x00000001030b8f1c _dispatch_main_queue_callback_4CF + 40

28  CoreFoundation                      0x000000018040e960 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12

29  CoreFoundation                      0x0000000180409078 __CFRunLoopRun + 1936

30  CoreFoundation                      0x00000001804084d4 CFRunLoopRunSpecific + 572

31  GraphicsServices                    0x000000018ef2aae4 GSEventRunModal + 160

32  UIKitCore                           0x00000001853d0a28 -[UIApplication _run] + 868

33  UIKitCore                           0x00000001853d46b0 UIApplicationMain + 124

34  SwiftUI                             0x00000001ccf100e4 OUTLINED_FUNCTION_65 + 492

35  SwiftUI                             0x00000001ccf0ff8c OUTLINED_FUNCTION_65 + 148

36  SwiftUI                             0x00000001ccbcd6d8 OUTLINED_FUNCTION_0 + 92

37  meetingbot4ios                      0x0000000102cf7618 $s14meetingbot4ios10MeetingBotV5$mainyyFZ + 40

38  meetingbot4ios                      0x0000000102d07e10 main + 12

39  dyld                                0x0000000103635544 start_sim + 20

40  ???                                 0x000000010314a154 0x0 + 4346650964

41  ???                                 0x8e7d000000000000 0x0 + 10267362725474598912

)

libc++abi: terminating due to uncaught exception of type NSException

下面是我的解决办法。

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

    // 其他代码...
}

只需要在其中增加var window: UIWindow?这行代码就可以了。