介紹ViewController時崩潰

Question

我正在嘗試presentViewController，但由於以下堆棧跟蹤而崩潰。 可以請一個人檢查和幫助。

呈現給presentViewController的代碼

func moveToChatView(){
 SwiftSpinner.show(Strings.loading)

  let destViewController:GroupChatViewController  = UIStoryboard(name:      "GroupChat", bundle:  nil).instantiateViewControllerWithIdentifier("GroupChatViewController") as!    GroupChatViewController
 destViewController.currentRiderRideID = self.riderRideId!
if NSThread.isMainThread() == true{
self.presentViewController(destViewController, animated: true, completion:   nil)
 }else{
    dispatch_sync(dispatch_get_main_queue()){
  self.presentViewController(destViewController, animated: true, completion:   nil)
   }
 }
}

致命例外：NSRangeException 0的CoreFoundation 0x182b482d8 exceptionPreprocess 1 libobjc.A.dylib 0x1948140e4 objc_exception_throw 2的CoreFoundation 0x182a2f4c0 CFStringConvertNSStringEncodingToEncoding 3的UIKit 0x1879e01b4 - [UINib instantiateWithOwner：選擇：] 4的UIKit 0x1878dc318 - [UIViewController中_loadViewFromNibNamed：束：] 5的UIKit 0x1875c09bc - [UIViewController中loadViewIfRequired] 6 UIKit 0x1875c0928-[UIViewController視圖] 7 UIKit 0x187cb618c-[_ UIFullscreenPresentationController _setPresentedViewController：] 8 UIKit 0x1878c60dc-[UIPresentationController initWithPresentedViewController：presentingViewController：] 9 UIKit 0x1878e2present-[UIViewController：]動畫：完成：] _ block_invoke 11 UIKit 0x1876ae0ec-[UIViewController presentViewController：動畫：完成：] 12 Quickride 0x100451968部分申請LiveRideMapViewController。（moveToChatView （） - >（））（閉合＃1）（LiveRideMapViewController.swift：1868）13 libdispatch.dylib 0x194e91954 _dispatch_client_callout 14 libdispatch.dylib 0x194e9f590 _dispatch_barrier_sync_f_slow_invoke 15 libdispatch.dylib 0x194e91954 _dispatch_client_callout 16 libdispatch.dylib 0x194e9620c _dispatch_main_queue_callback_4CF 17的CoreFoundation 0x182aff7f8 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE 18的CoreFoundation 0x182afd8a0 __CFRunLoopRun 19 CoreFoundation 0x182a292d4 CFRunLoopRunSpecific 20 GraphicsServices 0x18c47f6fc GSEventRunModal 21 UIKit 0x187626f40 UIApplicationMain 22 Quickride 0x100259a70 main（AppDelegate.swift：23）23 libdyld.dylib 0x194

Answer 1

作為一個規則不使用DISPATCH- 同步 ，而是使用DISPATCH- 異步和你沒有，如果你檢查主線程上，如果它是一個UI操作有一個機會，這將是上一回線剛將dispatch_ async同步到主隊列，它將在主隊列的下一個運行循環上執行UI操作，並且UI將“平滑”，請嘗試以下操作：

func moveToChatView(){
    SwiftSpinner.show(Strings.loading)

    let destViewController:GroupChatViewController  = UIStoryboard(name:"GroupChat", bundle:  nil).instantiateViewControllerWithIdentifier("GroupChatViewController") as!    GroupChatViewController
    destViewController.currentRiderRideID = self.riderRideId!
    dispatch_async(dispatch_get_main_queue()){
       self.presentViewController(destViewController, animated: true,completion:nil)
   }
}