我已将CG_CONTEXT_SHOW_BACKTRACE环境变量设置为YES,因为我有以下错误CGContextSaveGState：无效上下文0x0.
以下堆栈跟踪没有帮助我.
<Error>: CGContextSaveGState: invalid context 0x0. Backtrace:
<-[UIStatusBarBatteryItemView contentsImage]+773>
<-[UIStatusBarItemView updateContentsAndWidth]+36>
<-[UIStatusBarItemView initWithItem:data:actions:style:]+503>
<+[UIStatusBarItemView createViewForItem:withData:actions:foregroundStyle:]+159>
<-[UIStatusBarLayoutManager _createViewForItem:withData:actions:]+168>
<-[UIStatusBarLayoutManager _prepareEnabledItemType:withEnabledItems:withData:actions:itemAppearing:itemDisappearing:]+3
<-[UIStatusBarLayoutManager prepareEnabledItems:withData:actions:]+108>
<-[UIStatusBarForegroundView _setStatusBarData:actions:animated:]+951>
<-[UIStatusBarForegroundView setStatusBarData:actions:animated:]+874>
<__51-[UIStatusBar _prepareToSetStyle:animation:forced:]_block_invoke+443>
<+[UIView(Animation) performWithoutAnimation:]+82>
<-[UIStatusBar _prepareToSetStyle:animation:forced:]+935>
<-[UIStatusBar _requestStyleAttributes:animationParameters:forced:]+404>
<-[UIStatusBar requestStyle:animationParameters:forced:]+490>
<-[UIStatusBar requestStyle:animated:forced:]+113>
<-[UIStatusBar forceUpdateStyleOverrides:]+97>
<-[UIStatusBar _evaluateServerRegistration]+294>
<-[UIStatusBar didMoveToSuperview]+33>
<__45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke+683>
<-[UIView(Hierarchy) _postMovedFromSuperview:]+484>
<-[UIView(Internal) _addSubview:positioned:relativeTo:]+2305>
<-[UIView(Hierarchy) addSubview:]+56>
<-[UIStatusBarWindow setStatusBar:]+311>
<-[UIApplication _createStatusBarWithRequestedStyle:orientation:hidden:]+384>
<-[UIApplication _runWithMainScene:transitionContext:completion:]+1047>
<__84-[UIApplication _handleApplicationActivationWithScene:transitionContext:completion:]_block_invo
<-[UIApplication workspaceDidEndTransaction:]+163>
<__37-[FBSWorkspace clientEndTransaction:]_block_invoke_2+71>
<__40-[FBSWorkspace _performDelegateCallOut:]_block_invoke+54>
<-[FBSSerialQueue _performNext]+184>
<-[FBSSerialQueue _performNextFromRunLoopSource]+52>
<FBSSerialQueueRunLoopSourceHandler+33>
<__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__+15>
<__CFRunLoopDoSources0+523>
<__CFRunLoopRun+1032>
<CFRunLoopRunSpecific+470>
<CFRunLoopRunInMode+123>
<-[UIApplication _run]+540>
<UIApplicationMain+160>
<main+94>
在发布时发生错误,电池视图似乎有问题.这个错误是否响了你的任何钟声？
FWW我的应用程序大多是用Swift 2.0编写的,在iOS9上使用Xcode 7b6.
