防止UIDocumentInteractionController PresentPreview崩潰我的應用程序

Question

我試圖用UidocumentInteractionController預覽文件。似乎很簡單，但隨機的應用程序與SIGSEGV崩潰，幾個小時後嘗試所有類型的黑客，我只是沒有得到什麼失蹤。

此代碼是從我的UIViewController類叫做：

void Initialize() 
{ 
    mInteractionControllerDelegate = new UIDocumentInteractionControllerDelegateClass(this, mFile); 
    mInteractionController = UIDocumentInteractionController.FromUrl(NSUrl.FromFilename(mFile.Name)); 
    mInteractionController.Delegate = mInteractionControllerDelegate; 
} 

mInteractionControllerDelegate和mInteractionController是我的視圖控制器類的成員變量（我試過了，爲了確保事件不是一個變量射擊那會是GCed）

我提出一個按鈕點擊預覽（與MPMoviePlayerViewController部分工作正常：

void btnShowTouchUpInside (object sender, EventArgs e) 
{ 
    if (mFile.Name.EndsWith(".mpeg") || mFile.Name.EndsWith(".avi") || mFile.Name.EndsWith(".mpg")) 
    { 
     MPMoviePlayerViewController mp = new MPMoviePlayerViewController(NSUrl.FromString(mFile.VideoURL)); 
     this.PresentMoviePlayerViewController(mp); 
    } 
    else 
    { 
     InvokeOnMainThread(delegate { 
      mInteractionController.PresentPreview(true); 
     });; 
    } 
} 

在某些情況下，預覽會起作用（例如小txt文件：但我不確定文件大小=>崩潰相關性）。但是，如果我試圖用例如（500 KO）一些較大的PNG文件，我看到預覽幾秒鐘，然後再應用程序崩潰與下面的堆棧跟蹤：

Stacktrace: 

at (wrapper managed-to-native) MonoTouch.ObjCRuntime.Messaging.void_objc_msgSend (intptr,intptr) <IL 0x00024, 0xffffffff> 
at MonoTouch.Foundation.NSObject/MonoTouch_Disposer.Drain (MonoTouch.Foundation.NSObject) [0x0002a] in /Users/plasma/Source/iphone/monotouch/Foundation/NSObject.cs:305 
at (wrapper runtime-invoke) <Module>.runtime_invoke_void__this___object (object,intptr,intptr,intptr) <IL 0x00052, 0xffffffff> 
at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication.UIApplicationMain (int,string[],intptr,intptr) <IL 0x0009f, 0xffffffff> 
at MonoTouch.UIKit.UIApplication.Main (string[],string,string) [0x00038] in /Users/plasma/Source/iphone/monotouch/UIKit/UIApplication.cs:26 
at MonoTouch.UIKit.UIApplication.Main (string[]) [0x00000] in /Users/plasma/Source/iphone/monotouch/UIKit/UIApplication.cs:31 
at DTS.Application.Main (string[]) [0x00000] in /Users/seb/Projects/DTS/DTS/Main.cs:14 
at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <IL 0x00050, 0xffffffff> 

Native stacktrace: 

0 DTS         0x000d1965 mono_handle_native_sigsegv + 343 
1 DTS         0x0000ffb4 mono_sigsegv_signal_handler + 322 
2 libSystem.B.dylib     0x98a9f45b _sigtramp + 43 
3 ???         0xffffffff 0x0 + 4294967295 
4 ???         0x0d24837c 0x0 + 220496764 
5 ???         0x077520d6 0x0 + 125116630 
6 DTS         0x0000fd6f mono_jit_runtime_invoke + 1332 
7 DTS         0x001ee239 mono_runtime_invoke + 137 
8 DTS         0x0029e9ab monotouch_trampoline + 2527 
9 Foundation       0x0140e94e __NSThreadPerformPerform + 251 
10 CoreFoundation      0x00ea08ff __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15 
11 CoreFoundation      0x00dfe88b __CFRunLoopDoSources0 + 571 
12 CoreFoundation      0x00dfdd86 __CFRunLoopRun + 470 
13 CoreFoundation      0x00dfd840 CFRunLoopRunSpecific + 208 
14 CoreFoundation      0x00dfd761 CFRunLoopRunInMode + 97 
15 GraphicsServices     0x0404c1c4 GSEventRunModal + 217 
16 GraphicsServices     0x0404c289 GSEventRun + 115 
17 UIKit        0x01ce0c93 UIApplicationMain + 1160 
18 ???         0x09d540a3 0x0 + 164970659 
19 ???         0x09d53e74 0x0 + 164970100 
20 ???         0x09d53474 0x0 + 164967540 
21 ???         0x09d532cc 0x0 + 164967116 
22 ???         0x09d5341e 0x0 + 164967454 
23 DTS         0x0000fd6f mono_jit_runtime_invoke + 1332 
24 DTS         0x001ee239 mono_runtime_invoke + 137 
25 DTS         0x001f0920 mono_runtime_exec_main + 669 
26 DTS         0x001efd0a mono_runtime_run_main + 843 
27 DTS         0x000a3c62 mono_jit_exec + 200 
28 DTS         0x002a25eb main + 3838 
29 DTS         0x000030c9 _start + 208 
30 DTS         0x00002ff8 start + 40 

Debug info from gdb: 

/tmp/mono-gdb-commands.VWK7bK:1: Error in sourced command file: 
unable to debug self 

================================================================= 
Got a SIGSEGV while executing native code. This usually indicates 
a fatal error in the mono runtime or one of the native libraries 
used by your application. 
================================================================= 

最後的線索：這是代碼對於UIDocumentInteractionControllerDelegateClass（從其他問題上創建SO）：

public class UIDocumentInteractionControllerDelegateClass : UIDocumentInteractionControllerDelegate 
{ 
    private UIViewController mViewController; 
    private DTSVirtualFile mFile; 

    public UIDocumentInteractionControllerDelegateClass(UIViewController viewController, DTSVirtualFile file) 
    { 
     mViewController = viewController; 
     mFile = file; 
    } 

    public override UIViewController ViewControllerForPreview (UIDocumentInteractionController controller) 
    { 
     return mViewController; 
    } 

    public override UIView ViewForPreview (UIDocumentInteractionController controller) 
    { 
     return mViewController.View; 
    } 

    public override RectangleF RectangleForPreview (UIDocumentInteractionController controller) 
    { 
     return mViewController.View.Frame; 
    } 

    public override void DidEndPreview (UIDocumentInteractionController controller) 
    { 
     mFile.DeleteCopy(); 
    } 

    public override void DidDismissOptionsMenu (UIDocumentInteractionController controller) 
    { 
     // TODO: Implement - see: http://go-mono.com/docs/index.aspx?link=T%3aMonoTouch.Foundation.ModelAttribute 
    } 

    public override void WillBeginPreview (UIDocumentInteractionController controller) 
    { 
     Console.WriteLine("WillBeginPreview");   
    } 

    public override void WillBeginSendingToApplication (UIDocumentInteractionController controller) 
    { 
     // TODO: Implement - see: http://go-mono.com/docs/index.aspx?link=T%3aMonoTouch.Foundation.ModelAttribute 
    } 

    public override void WillPresentOpenInMenu (UIDocumentInteractionController controller) 
    { 
     // TODO: Implement - see: http://go-mono.com/docs/index.aspx?link=T%3aMonoTouch.Foundation.ModelAttribute 
    } 

    public override void WillPresentOptionsMenu (UIDocumentInteractionController controller) 
    { 
     // TODO: Implement - see: http://go-mono.com/docs/index.aspx?link=T%3aMonoTouch.Foundation.ModelAttribute 
    } 
} 

當我調試我能跨過PresentPreview罰款，但隨後崩潰之後的權利。如果我評論PresentPreview行，不會崩潰。

任何指針，解決方案？

Answer 1

有一個ABI bug影響MonoTouch的方法時，返回結構（而不​​是類），如的RectangleF並導致再次發生類似事故。設備構建（使用不同的ABO）不受此問題影響。

一種解決方法是避免返回結構，如重載方法：

public override RectangleF RectangleForPreview (UIDocumentInteractionController controller)