MonoTouch 异常未在设备上捕获

Question

我正在开发一个应用程序，该应用程序以前是在不使用故事板的情况下开发的，即所有视图都是在代码中创建的。因此，根据 this link，我正在尝试将自定义 MvxTouchViewsContainer 传递给 MvxTouchSetup.CreateTouchViewsContainer。

protected override IMvxTouchView CreateViewOfType(Type viewType, MvxViewModelRequest request)
    {

        UIStoryboard storyboard;

        try
        {

            storyboard = UIStoryboard.FromName(viewType.Name, null);
        }
        catch (Exception)
        {
            try {
                storyboard = UIStoryboard.FromName("MainStoryBoard_iPhone", null);
            }
            catch (Exception) {
                return base.CreateViewOfType (viewType, request);
            }
        }

        IMvxTouchView resultView = null;
        try {
             resultView = (IMvxTouchView) storyboard.InstantiateViewController(viewType.Name);

        } catch(Exception) {
            resultView = base.CreateViewOfType (viewType, request);

        }
        return resultView;
    }

基本上我会尝试找到故事板（如果存在），否则我会回退到从代码加载视图。 try - catch 异常在模拟器中运行良好。但是，当运行在实际 iOS 设备上并且应用程序崩溃时，不会捕获异常。

我得到一个 MonoTouch.Foundation.MonoTouchException，其中包含 NSInvalidArgumentException，这基本上是预期的，因为某些视图可能没有与之关联的故事板。

这是 Xamarin 错误吗？

Answer 1

使用自定义属性比 try/catch-method:

效果更好

public class FromStoryboardAttribute : Attribute
{
    public string StoryboardName { get; set; }

    public FromStoryboardAttribute(string storyboardName = null)
    {
        StoryboardName = storyboardName;
    }
}

这里是 StoryBoardContainer:

public class StoryBoardContainer : MvxTouchViewsContainer
{
    protected override IMvxTouchView CreateViewOfType(Type viewType, MvxViewModelRequest request)
    {
        var storyboardAttribute = viewType.GetCustomAttribute<FromStoryboardAttribute>();
        if (storyboardAttribute != null) {
            var storyboard = UIStoryboard.FromName(storyboardAttribute.StoryboardName ?? viewType.Name, null);
            var viewController = storyboard.InstantiateViewController(viewType.Name);
            return (IMvxTouchView) viewController;
        }
        return base.CreateViewOfType(viewType, request);
    }
}

用法：

// Will look for a UIViewController with identifier "MyView" inside a Storyboard named "MyView.storyboard"
[FromStoryboard]
public class MyView : MvxViewController
{
    public MyView(IntPtr handle) : base(handle) {}
}

// Will look for a UIVIewController with identifier "MyOtherViewInSameStoryboard" inside a Storyboard named "MyView.storyboard"
[FromStoryboard(StoryboardName = "MyView")]
public class MyOtherViewInSameStoryboard : MvxViewController
{
    public MyOtherViewInSameStoryboard(IntPtr handle) : base(handle) {}
}

MonoTouch 异常未在设备上捕获

MonoTouch Exception not getting caught on device

xamarin.ios

xamarin.android

ios

mvvmcross

xamarin