当我运行该项目时，它崩溃在“AppDelegate.swift”。
错误消息：
Optional(<UIButton: 0x7f9a0bd06610; frame = (0 0; 49 42); opaque = NO; autoresize = RM+BM; layer = <CALayer: 0x600001a316a0>>)
2019-04-07 11:10:54.335048+0800 IRIS iOS[60993:2979677] -[UIView setConstant:]: unrecognized selector sent to instance 0x7f9a0bd247f0
2019-04-07 11:10:54.351958+0800 IRIS iOS[60993:2979677] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIView setConstant:]: unrecognized selector sent to instance 0x7f9a0bd247f0'
*** First throw call stack:
(
0 CoreFoundation 0x00000001044ce6fb __exceptionPreprocess + 331
1 libobjc.A.dylib 0x0000000103a72ac5 objc_exception_throw + 48
2 CoreFoundation 0x00000001044ecab4 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
3 UIKitCore 0x000000010f950c3d -[UIResponder doesNotRecognizeSelector:] + 287
4 CoreFoundation 0x00000001044d3443 ___forwarding___ + 1443
5 CoreFoundation 0x00000001044d5238 _CF_forwarding_prep_0 + 120
6 IRIS iOS 0x000000010300cf1a $s8IRIS_iOS20SecondViewControllerC12isProcessingSbvW + 1418
7 IRIS iOS 0x000000010300d4c2 $s8IRIS_iOS20SecondViewControllerC12isProcessingSbvs + 274
8 IRIS iOS 0x000000010300d637 $s8IRIS_iOS20SecondViewControllerC11viewDidLoadyyF + 151
9 IRIS iOS 0x000000010300d844 $s8IRIS_iOS20SecondViewControllerC11viewDidLoadyyFTo + 36
10 UIKitCore 0x000000010f32243b -[UIViewController loadViewIfRequired] + 1183
11 UIKitCore 0x000000010f322868 -[UIViewController view] + 27
12 UIKitCore 0x000000010f95ac33 -[UIWindow addRootViewControllerViewIfPossible] + 122
13 UIKitCore 0x000000010f95b327 -[UIWindow _setHidden:forced:] + 289
14 UIKitCore 0x000000010f96df86 -[UIWindow makeKeyAndVisible] + 42
15 UIKitCore 0x000000010f91df1c -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 4555
16 UIKitCore 0x000000010f9230c6 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1617
17 UIKitCore 0x000000010f1686d6 __111-[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:]_block_invoke + 904
18 UIKitCore 0x000000010f170fce +[_UICanvas _enqueuePostSettingUpdateTransactionBlock:] + 153
19 UIKitCore 0x000000010f1682ec -[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:] + 236
20 UIKitCore 0x000000010f168c48 -[__UICanvasLifecycleMonitor_Compatability activateEventsOnly:withContext:completion:] + 1091
21 UIKitCore 0x000000010f166fba __82-[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:]_block_invoke + 782
22 UIKitCore 0x000000010f166c71 -[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:] + 433
23 UIKitCore 0x000000010f16b9b6 __125-[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:]_block_invoke + 576
24 UIKitCore 0x000000010f16c610 _performActionsWithDelayForTransitionContext + 100
25 UIKitCore 0x000000010f16b71d -[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:] + 223
26 UIKitCore 0x000000010f1706d0 -[_UICanvas scene:didUpdateWithDiff:transitionContext:completion:] + 392
27 UIKitCore 0x000000010f9219a8 -[UIApplication workspace:didCreateScene:withTransitionContext:completion:] + 514
28 UIKitCore 0x000000010f4d8dfa -[UIApplicationSceneClientAgent scene:didInitializeWithEvent:completion:] + 361
29 FrontBoardServices 0x000000010d982125 -[FBSSceneImpl _didCreateWithTransitionContext:completion:] + 448
30 FrontBoardServices 0x000000010d98bed6 __56-[FBSWorkspace client:handleCreateScene:withCompletion:]_block_invoke_2 + 283
31 FrontBoardServices 0x000000010d98b700 __40-[FBSWorkspace _performDelegateCallOut:]_block_invoke + 53
32 libdispatch.dylib 0x0000000108294db5 _dispatch_client_callout + 8
33 libdispatch.dylib 0x00000001082982ba _dispatch_block_invoke_direct + 300
34 FrontBoardServices 0x000000010d9bd146 __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 30
35 FrontBoardServices 0x000000010d9bcdfe -[FBSSerialQueue _performNext] + 451
36 FrontBoardServices 0x000000010d9bd393 -[FBSSerialQueue _performNextFromRunLoopSource] + 42
37 CoreFoundation 0x0000000104435be1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
38 CoreFoundation 0x0000000104435463 __CFRunLoopDoSources0 + 243
39 CoreFoundation 0x000000010442fb1f __CFRunLoopRun + 1231
40 CoreFoundation 0x000000010442f302 CFRunLoopRunSpecific + 626
41 GraphicsServices 0x000000010b4bb2fe GSEventRunModal + 65
42 UIKitCore 0x000000010f924ba2 UIApplicationMain + 140
43 IRIS iOS 0x000000010303135b main + 75
44 libdyld.dylib 0x0000000108309541 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
有人可以解释一下，或者至少告诉我需要写什么才能使它正确无误？
它的意思是你创建了一个按钮，但它的选择器方法还没有创建。