private Task <bool> GetAppearedOrDisappearedTask(Page page)
{
TaskCompletionSource <bool> tcs = new TaskCompletionSource <bool> ();
NavigationRenderer.ParentingViewController parentViewController = Platform.GetRenderer((VisualElement)page).ViewController.ParentViewController as NavigationRenderer.ParentingViewController;
if (parentViewController == null)
{
throw new NotSupportedException("ParentingViewController parent could not be found. Please file a bug.");
}
EventHandler appearing = (EventHandler)null;
EventHandler disappearing = (EventHandler)null;
appearing = (EventHandler)((s, e) =>
{
parentViewController.Appearing -= appearing;
parentViewController.Disappearing -= disappearing;
Device.BeginInvokeOnMainThread((Action)(() => tcs.SetResult(true)));
});
disappearing = (EventHandler)((s, e) =>
{
parentViewController.Appearing -= appearing;
parentViewController.Disappearing -= disappearing;
Device.BeginInvokeOnMainThread((Action)(() => tcs.SetResult(false)));
});
parentViewController.Appearing += appearing;
parentViewController.Disappearing += disappearing;
return(tcs.Task);
}
private void UpdateLeftBarButtonItem(NavigationRenderer.ParentingViewController containerController)
{
/*
* Page child = containerController.Child;
* Page page = Enumerable.LastOrDefault<Page> ((IEnumerable<Page>)((NavigationPage)this.Element).get_StackCopy ());
* if (child != page && NavigationPage.GetHasBackButton (child) || this.parentMasterDetailPage == null)
* return;
* if (!this.parentMasterDetailPage.ShouldShowToolbarButton ())
* {
* containerController.NavigationItem.LeftBarButtonItem = (UIBarButtonItem)null;
* }
* else
* {
* bool flag = this.parentMasterDetailPage.Master.Icon != null;
* if (flag)
* {
* try
* {
* containerController.NavigationItem.LeftBarButtonItem = new UIBarButtonItem (new UIImage ((string)this.parentMasterDetailPage.Master.Icon), UIBarButtonItemStyle.Plain, (EventHandler)((o, e) => this.parentMasterDetailPage.IsPresented = !this.parentMasterDetailPage.IsPresented));
* }
* catch (Exception ex)
* {
* flag = false;
* }
* }
* if (flag)
* return;
* containerController.NavigationItem.LeftBarButtonItem = new UIBarButtonItem (this.parentMasterDetailPage.Master.Title, UIBarButtonItemStyle.Plain, (EventHandler)((o, e) => this.parentMasterDetailPage.IsPresented = !this.parentMasterDetailPage.IsPresented));
* }
*/
}