private bool HasViewModel(object view, Type viewModelType)
{
if (_navigationTargetVm != null && _navigationTargetVm.GetType().Equals(viewModelType))
{
return(true);
}
if (view == null)
{
return(false);
}
var viewModel = ViewManagerEx.GetDataContext(view) as IViewModel;
if (viewModel == null)
{
return(false);
}
var vmType = viewModel.GetType();
#if NETFX_CORE || WINDOWSCOMMON || XAMARIN_FORMS
if (!viewModelType.GetTypeInfo().IsGenericType)
#else
if (!viewModelType.IsGenericType)
#endif
{ return(vmType.Equals(viewModelType)); }
#if NETFX_CORE || WINDOWSCOMMON || XAMARIN_FORMS
if (!vmType.GetTypeInfo().IsGenericType)
#else
if (!vmType.IsGenericType)
#endif
{ return(false); }
return(vmType.GetGenericTypeDefinition().Equals(viewModelType.GetGenericTypeDefinition()));
}
protected virtual IViewModel GetViewModelForView([NotNull] NavigationEventArgsBase args,
[CanBeNull] IViewModel navigationViewModel, [NotNull] INavigationContext context, [NotNull] Type vmType)
{
var view = args.Content;
if (navigationViewModel != null)
{
ViewManager.InitializeViewAsync(navigationViewModel, view).WithTaskExceptionHandler(this);
return(navigationViewModel);
}
//Trying to get from cache.
IViewModel vm = TryTakeViewModelFromCache(context, view);
if (HasViewModel(view, vmType))
{
return((IViewModel)ViewManagerEx.GetDataContext(view));
}
if (vm == null)
{
IDataContext viewModelState = null;
#if WINDOWS_PHONE || NETFX_CORE || WINDOWSCOMMON
viewModelState = PlatformExtensions.GetViewModelState(view);
if (viewModelState != null)
{
PlatformExtensions.SetViewModelState(view, null);
}
#endif
vm = ViewModelProvider.RestoreViewModel(viewModelState, new DataContext
{
{ InitializationConstants.ViewModelType, vmType }
}, false);
}
if (vm != null)
{
ViewManager.InitializeViewAsync(vm, view).WithTaskExceptionHandler(this);
}
return(vm);
}
