Question

我有一个带有NavigationController的简单测试应用程序，它扩展了UINavigationController

[MonoTouch.Foundation.Register("NavigationController")]
public class NavigationController : UINavigationController
{
    public NavigationController (IntPtr handle) : base (handle)
    {

    }

    [Export ("initWithCoder:")]
    public NavigationController (NSCoder coder) : base (coder)
    {

    }

    public NavigationController (UIViewController rootViewController) : base(rootViewController)
    {

    }

    public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();

        View.BackgroundColor = UIColor.Green;
    }
}

我还有一个扩展UITableViewController的CustomersTableViewController（这里Source不具影响力）。在ViewDidLoad方法中，我创建了一个UISearchBar，然后将其添加到TableHeaderView。

public class CustomersTableViewController : UITableViewController
{
    UISearchBar _searchBar;

    public CustomersTableViewController(UITableViewStyle style) : base(style)
    {
    }

    public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();

        _searchBar = CreateSearchBar ();
        _searchBar.SearchButtonClicked += OnSearchBarSearchButtonClicked;

        TableView.TableHeaderView = _searchBar;

    }

    void OnSearchBarSearchButtonClicked (object sender, EventArgs e)
    {

    }

    static UISearchBar CreateSearchBar ()
    {
        UISearchBar search = new UISearchBar ();
        search.Placeholder = "Search Customers";
        search.SizeToFit ();
        search.AutocorrectionType = UITextAutocorrectionType.No;
        search.AutocapitalizationType = UITextAutocapitalizationType.None;
        return search;
    }
}

在Main.cs中，我运行以下代码片段。如果我通过代码或通过xib创建navigationController，它是相同的。

// The name AppDelegate is referenced in the MainWindow.xib file.
public partial class AppDelegate : UIApplicationDelegate
{
    // This method is invoked when the application has loaded its UI and its ready to run
    public override bool FinishedLaunching (UIApplication app, NSDictionary options)
    {
        // If you have defined a view, add it here:
        //window.AddSubview (navigationController.View);

        NavigationController navigationController = new NavigationController(new CustomersTableViewController(UITableViewStyle.Plain));
        window.AddSubview (navigationController.View);

        window.MakeKeyAndVisible ();

        return true;
    }
}

图形界面显示正确，但是当我点击searchBar时，应用程序崩溃并出现以下错误。

Stacktrace:

 at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication.UIApplicationMain (int,string[],intptr,intptr) <IL 0x0009f, 0xffffffff>
 at MonoTouch.UIKit.UIApplication.Main (string[],string,string) [0x00042] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:29
 at MonoTouch.UIKit.UIApplication.Main (string[]) [0x00000] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:34
 at TestSearchBar.Application.Main (string[]) [0x00000] in /Users/lorenzo/Projects/TestSearchBar/TestSearchBar/Main.cs:13
 at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <IL 0x00050, 0xffffffff>

Native stacktrace:

0   TestSearchBar                       0x000d1e9c mono_handle_native_sigsegv + 343
1   TestSearchBar                       0x000100e0 mono_sigsegv_signal_handler + 322
2   libSystem.B.dylib                   0x9373205b _sigtramp + 43
3   ???                                 0xffffffff 0x0 + 4294967295
4   UIKit                               0x01d73227 -[UITextField canBecomeFirstResponder] + 204
5   UIKit                               0x01da7226 -[UIResponder becomeFirstResponder] + 171
6   UIKit                               0x01f6f961 -[UITextInteractionAssistant setFirstResponderIfNecessary] + 208
7   UIKit                               0x01f725e2 -[UITextInteractionAssistant oneFingerTap:] + 1676
8   UIKit                               0x01f694f2 -[UIGestureRecognizer _updateGestureWithEvent:] + 730
9   UIKit                               0x01f654fe -[UIGestureRecognizer _delayedUpdateGesture] + 47
10  UIKit                               0x01f6bafc _UIGestureRecognizerUpdateObserver + 584
11  UIKit                               0x01f6bce1 _UIGestureRecognizerUpdateGesturesFromSendEvent + 51
12  UIKit                               0x01cff32a -[UIWindow _sendGesturesForEvent:] + 1292
13  UIKit                               0x01cfaca3 -[UIWindow sendEvent:] + 105
14  UIKit                               0x01cddc37 -[UIApplication sendEvent:] + 447
15  UIKit                               0x01ce2f2e _UIApplicationHandleEvent + 7576
16  GraphicsServices                    0x04053992 PurpleEventCallback + 1550
17  CoreFoundation                      0x00ea6944 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
18  CoreFoundation                      0x00e06cf7 __CFRunLoopDoSource1 + 215
19  CoreFoundation                      0x00e03f83 __CFRunLoopRun + 979
20  CoreFoundation                      0x00e03840 CFRunLoopRunSpecific + 208
21  CoreFoundation                      0x00e03761 CFRunLoopRunInMode + 97
22  GraphicsServices                    0x040521c4 GSEventRunModal + 217
23  GraphicsServices                    0x04052289 GSEventRun + 115
24  UIKit                               0x01ce6c93 UIApplicationMain + 1160
25  ???                                 0x077f6764 0x0 + 125790052
26  ???                                 0x077f6630 0x0 + 125789744
27  ???                                 0x077f5f60 0x0 + 125788000
28  ???                                 0x077f5eac 0x0 + 125787820
29  ???                                 0x077f5f37 0x0 + 125787959
30  TestSearchBar                       0x0000fe9b mono_jit_runtime_invoke + 1332
31  TestSearchBar                       0x001ee961 mono_runtime_invoke + 137
32  TestSearchBar                       0x001f1048 mono_runtime_exec_main + 669
33  TestSearchBar                       0x001f0432 mono_runtime_run_main + 843
34  TestSearchBar                       0x000a3f9e mono_jit_exec + 200
35  TestSearchBar                       0x002a3d21 main + 3733
36  TestSearchBar                       0x00003179 _start + 208
37  TestSearchBar                       0x000030a8 start + 40

=================================================================
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.
=================================================================

有什么建议吗？这是一个MT bug吗？我错过了什么吗？提前谢谢。

编辑：我用Mono 2.10.4运行MT 4.2.2。使用Mono 2.10.5时，崩溃仍然存在。

Answer 1

改变你的：

   NavigationController navigationController = new NavigationController(new CustomersTableViewController(UITableViewStyle.Plain));

从一个局部变量（GC可以在不再使用后立即收集）到一个字段中（只要该类型的实例存在，它将使引用保持活动状态）。 E.g。

   private NavigationController navigationController;
   ...

   navigationController = new NavigationController(new CustomersTableViewController(UITableViewStyle.Plain));

请注意：

   window.AddSubview (navigationController.View);

只会保留对视图的引用，而不会引用它的父级（常见错误）。

UISearchBar，UITableViewController和UINavigationController，在执行本机代码时获得了SIGSEGV

1 个答案: