我在ViewController.swift的第659行报告了崩溃。但是，我不确定崩溃日志中报告的问题，我无法设置背景颜色。请指教。提前谢谢。
mysql -u rootViewController.swift行是659
Thread 0 name: main Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0 libswiftCore.dylib 0x00000001015bca18 0x101588000 + 215576
1 libswiftCore.dylib 0x00000001015bca18 0x101588000 + 215576
2 libswiftCore.dylib 0x00000001015dc7c8 0x101588000 + 346056
3 libswiftCore.dylib 0x00000001015dc5d0 0x101588000 + 345552
4 Test UAT 0x00000001005a0fe4 ViewController.viewDidLoad() -> () (ViewController.swift:659)
5 Test UAT 0x00000001005a102c @objc ViewController.viewDidLoad() -> () (ViewController.swift:0)
6 UIKit 0x000000019206b924 -[UIViewController loadViewIfRequired] + 1056
7 UIKit 0x000000019206b4ec -[UIViewController view] + 28
8 UIKit 0x0000000192071c98 -[UIWindow addRootViewControllerViewIfPossible] + 76
9 UIKit 0x000000019206f138 -[UIWindow _setHidden:forced:] + 272
10 UIKit 0x00000001920e168c -[UIWindow makeKeyAndVisible] + 48
11 UIKit 0x00000001922edcb8 -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 4068
12 UIKit 0x00000001922f3808 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1656
13 UIKit 0x0000000192308104 __84-[UIApplication _handleApplicationActivationWithScene:transitionContext:completion:]_block_invoke.3139 + 48
14 UIKit 0x00000001922f07ec -[UIApplication workspaceDidEndTransaction:] + 168
15 FrontBoardServices 0x000000018dd9392c __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 36
16 FrontBoardServices 0x000000018dd93798 -[FBSSerialQueue _performNext] + 176
17 FrontBoardServices 0x000000018dd93b40 -[FBSSerialQueue _performNextFromRunLoopSource] + 56
18 CoreFoundation 0x000000018c16ab5c __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24
19 CoreFoundation 0x000000018c16a4a4 __CFRunLoopDoSources0 + 524
20 CoreFoundation 0x000000018c1680a4 __CFRunLoopRun + 804
21 CoreFoundation 0x000000018c0962b8 CFRunLoopRunSpecific + 444
22 UIKit 0x00000001920d67b0 -[UIApplication _run] + 608
23 UIKit 0x00000001920d1534 UIApplicationMain + 208
24 Test UAT 0x000000010053a780 main (AppDelegate.swift:43)
25 libdyld.dylib 0x000000018b0795b8 start + 4