ios 如何设置 CG_CONTEXT_SHOW_BACKTRACE 环境变量？
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How can I set CG_CONTEXT_SHOW_BACKTRACE environmental variable?
提问by l1ghthouse
I have three buttons in my view. After setting the cornerRadus in the viewDidLoad() : button.layer.cornerRadius = 20I get the following error message in the log:
我有三个按钮。在 viewDidLoad() 中设置 cornerRadus 后：button.layer.cornerRadius = 20我在日志中收到以下错误消息：
<Error>: CGContextSaveGState: invalid context 0x0.
If you want to see the backtrace, please set
CG_CONTEXT_SHOW_BACKTRACE environmental variable.
Questions:
问题：
How can I set CG_CONTEXT_SHOW_BACKTRACE environmental variable?- Or how can I fix this warning?
如何设置 CG_CONTEXT_SHOW_BACKTRACE 环境变量？- 或者我该如何解决这个警告？
Okay I've the backtrace now from the message. It doesn't make any sense to me. Some help please...
好的，我现在从消息中获得了回溯。这对我来说没有任何意义。请一些帮助...
Aug 7 14:27:00 <Error>: CGContextSaveGState: invalid context 0x0. Backtrace:
<-[UIStatusBarItemView updateContentsAndWidth]+33>
<-[UIStatusBarItemView initWithItem:data:actions:style:]+477>
<+[UIStatusBarItemView createViewForItem:withData:actions:foregroundStyle:]+134>
<-[UIStatusBarLayoutManager _createViewForItem:withData:actions:]+163>
<-[UIStatusBarLayoutManager _prepareEnabledItemType:withEnabledItems:withData:actions:itemAppearing:itemDisappearing:]+36
<-[UIStatusBarLayoutManager prepareEnabledItems:withData:actions:]+92>
<-[UIStatusBarForegroundView _setStatusBarData:actions:animated:]+797>
<-[UIStatusBarForegroundView setStatusBarData:actions:animated:]+332>
<__51-[UIStatusBar _prepareToSetStyle:animation:forced:]_block_invoke+360>
<+[UIView(Animation) performWithoutAnimation:]+65>
<-[UIStatusBar _prepareToSetStyle:animation:forced:]+866>
<-[UIStatusBar _requestStyleAttributes:animationParameters:forced:]+391>
<-[UIStatusBar requestStyle:animationParameters:forced:]+437>
<-[UIStatusBar requestStyle:animated:forced:]+90>
<-[UIStatusBar _evaluateServerRegistration]+250>
<__45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke+590>
<-[UIView(Hierarchy) _postMovedFromSuperview:]+544>
<-[UIView(Internal) _addSubview:positioned:relativeTo:]+1967>
<-[UIStatusBarWindow setStatusBar:]+288>
<-[UIApplication _createStatusBarWithRequestedStyle:orientation:hidden:]+340>
<-[UIApplication _runWithMainScene:transitionContext:completion:]+950>
<-[UIApplication workspaceDidEndTransaction:]+188>
<-[FBSSerialQueue _performNext]+192>
<-[FBSSerialQueue _performNextFromRunLoopSource]+45>
<__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__+17>
<__CFRunLoopDoSources0+556>
<__CFRunLoopRun+867>
<CFRunLoopRunSpecific+488>
<-[UIApplication _run]+402>
<UIApplicationMain+171>
<main+117>
Aug 7 14:27:00 <Error>: CGContextTranslateCTM: invalid context 0x0. Backtrace:
<-[UIStatusBarItemView updateContentsAndWidth]+33>
<-[UIStatusBarItemView initWithItem:data:actions:style:]+477>
<+[UIStatusBarItemView createViewForItem:withData:actions:foregroundStyle:]+134>
<-[UIStatusBarLayoutManager _createViewForItem:withData:actions:]+163>
<-[UIStatusBarLayoutManager _prepareEnabledItemType:withEnabledItems:withData:actions:itemAppearing:itemDisappearing:]+36
<-[UIStatusBarLayoutManager prepareEnabledItems:withData:actions:]+92>
<-[UIStatusBarForegroundView _setStatusBarData:actions:animated:]+797>
<-[UIStatusBarForegroundView setStatusBarData:actions:animated:]+332>
<__51-[UIStatusBar _prepareToSetStyle:animation:forced:]_block_invoke+360>
<+[UIView(Animation) performWithoutAnimation:]+65>
<-[UIStatusBar _prepareToSetStyle:animation:forced:]+866>
<-[UIStatusBar _requestStyleAttributes:animationParameters:forced:]+391>
<-[UIStatusBar requestStyle:animationParameters:forced:]+437>
<-[UIStatusBar requestStyle:animated:forced:]+90>
<-[UIStatusBar _evaluateServerRegistration]+250>
<__45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke+590>
<-[UIView(Hierarchy) _postMovedFromSuperview:]+544>
<-[UIView(Internal) _addSubview:positioned:relativeTo:]+1967>
<-[UIStatusBarWindow setStatusBar:]+288>
<-[UIApplication _createStatusBarWithRequestedStyle:orientation:hidden:]+340>
<-[UIApplication _runWithMainScene:transitionContext:completion:]+950>
<-[UIApplication workspaceDidEndTransaction:]+188>
<-[FBSSerialQueue _performNext]+192>
<-[FBSSerialQueue _performNextFromRunLoopSource]+45>
<__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__+17>
<__CFRunLoopDoSources0+556>
<__CFRunLoopRun+867>
<CFRunLoopRunSpecific+488>
<-[UIApplication _run]+402>
<UIApplicationMain+171>
<main+117>
Aug 7 14:27:00 <Error>: CGContextRestoreGState: invalid context 0x0. Backtrace:
<-[UIStatusBarItemView updateContentsAndWidth]+33>
<-[UIStatusBarItemView initWithItem:data:actions:style:]+477>
<+[UIStatusBarItemView createViewForItem:withData:actions:foregroundStyle:]+134>
<-[UIStatusBarLayoutManager _createViewForItem:withData:actions:]+163>
<-[UIStatusBarLayoutManager _prepareEnabledItemType:withEnabledItems:withData:actions:itemAppearing:itemDisappearing:]+36
<-[UIStatusBarLayoutManager prepareEnabledItems:withData:actions:]+92>
<-[UIStatusBarForegroundView _setStatusBarData:actions:animated:]+797>
<-[UIStatusBarForegroundView setStatusBarData:actions:animated:]+332>
<__51-[UIStatusBar _prepareToSetStyle:animation:forced:]_block_invoke+360>
<+[UIView(Animation) performWithoutAnimation:]+65>
<-[UIStatusBar _prepareToSetStyle:animation:forced:]+866>
<-[UIStatusBar _requestStyleAttributes:animationParameters:forced:]+391>
<-[UIStatusBar requestStyle:animationParameters:forced:]+437>
<-[UIStatusBar requestStyle:animated:forced:]+90>
<-[UIStatusBar _evaluateServerRegistration]+250>
<__45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke+590>
<-[UIView(Hierarchy) _postMovedFromSuperview:]+544>
<-[UIView(Internal) _addSubview:positioned:relativeTo:]+1967>
<-[UIStatusBarWindow setStatusBar:]+288>
<-[UIApplication _createStatusBarWithRequestedStyle:orientation:hidden:]+340>
<-[UIApplication _runWithMainScene:transitionContext:completion:]+950>
<-[UIApplication workspaceDidEndTransaction:]+188>
<-[FBSSerialQueue _performNext]+192>
<-[FBSSerialQueue _performNextFromRunLoopSource]+45>
<__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__+17>
<__CFRunLoopDoSources0+556>
<__CFRunLoopRun+867>
<CFRunLoopRunSpecific+488>
<-[UIApplication _run]+402>
<UIApplicationMain+171>
<main+117>
采纳答案by Greg Robertson
It's a bug in 9b5:
https://forums.developer.apple.com/thread/13683
这是 9b5 中的一个错误：https://forums.developer.apple.com/thread/13683
File a RADAR with Apple.
向 Apple 提交 RADAR。
回答by utogaria
You can set an environmental variable via this menu: Product -> Scheme -> Edit Scheme. Under the "Run" item, locate the "Arguments" tab, you'll see "Environmental Variables" in the tab, Add CG_CONTEXT_SHOW_BACKTRACEand set its value to YES.
您可以通过此菜单设置环境变量：产品 -> 方案 -> 编辑方案。在“运行”项下，找到“参数”选项卡，您将在选项卡中看到“环境变量”，添加CG_CONTEXT_SHOW_BACKTRACE并将其值设置为 YES。
回答by Weles
回答by Nghia Luong
On Xcode 7:
在 Xcode 7 上：
In case you still want the status bar is hidden, just change UIViewControllerBasedStatusBarAppearancein the Info.plistfile into View controller-based status bar appearance. Don't forget to set it by NO
如果您仍然希望隐藏状态栏，只需UIViewControllerBasedStatusBarAppearance将Info.plist文件更改为View controller-based status bar appearance. 不要忘记设置它NO
