MvvmCross bind to progress indicator in MvxDialogViewController - xamarin.ios

Question

I have a MvxDialogViewController and I'm trying to use the progress indicator shown in the Xamarin example by adding bindable properties.
I can get the indicator to appear when I set Visble to true programatically but not when I bind to a vm property.
Here is the view code:
var bindings = this.CreateInlineBindingTarget<LoginViewModel>();
Root = new RootElement("Login")
{
new Section("Login Credentials")
{
new EntryElement("Username", "Enter user name").Bind(bindings, vm => vm.UserName),
new EntryElement("Password", "Enter password", "", true).Bind(bindings, vm => vm.Password)
}
};
_bindableProgress = new BindableProgress(UIScreen.MainScreen.Bounds).Bind(bindings, b => b.Visible, vm => vm.IsBusy);
_bindableProgress.Title = "Logging in...";
View.Add(_bindableProgress);
I also tried to bind like this:
var set = this.CreateBindingSet<LoginView, LoginViewModel>();
set.Bind(_bindableProgress).For(b => b.Title).To(vm => vm.ProgressTitle);
set.Bind(_bindableProgress).For(b => b.Visible).To(vm => vm.IsBusy);
set.Apply();
But neither way worked.
Here is by BindableProgress class:
public class BindableProgress : UIView
{
private UIActivityIndicatorView _activitySpinner;
private UILabel _loadingLabel;
public string Title { get; set; }
private bool _visible;
public bool Visible
{
get { return _visible; }
set
{
_visible = value;
if (_visible)
{
Show();
}
else
{
Hide();
}
}
}
public BindableProgress(RectangleF frame) : base(frame)
{
// configurable bits
BackgroundColor = UIColor.Black;
Alpha = 0;
AutoresizingMask = UIViewAutoresizing.FlexibleDimensions;
float labelHeight = 22;
float labelWidth = Frame.Width - 20;
// derive the center x and y
float centerX = Frame.Width/2;
float centerY = Frame.Height/2;
// create the activity spinner, center it horizontally and put it 5 points above center x
_activitySpinner = new UIActivityIndicatorView(UIActivityIndicatorViewStyle.WhiteLarge);
_activitySpinner.Frame = new RectangleF(
centerX - (_activitySpinner.Frame.Width / 2),
centerY - _activitySpinner.Frame.Height - 20,
_activitySpinner.Frame.Width,
_activitySpinner.Frame.Height);
_activitySpinner.AutoresizingMask = UIViewAutoresizing.FlexibleMargins;
AddSubview(_activitySpinner);
// create and configure the label
_loadingLabel = new UILabel(new RectangleF(
centerX - (labelWidth/2),
centerY + 20,
labelWidth,
labelHeight
));
_loadingLabel.BackgroundColor = UIColor.Clear;
_loadingLabel.TextColor = UIColor.White;
_loadingLabel.TextAlignment = UITextAlignment.Center;
_loadingLabel.AutoresizingMask = UIViewAutoresizing.FlexibleMargins;
AddSubview(_loadingLabel);
}
private void Show()
{
_loadingLabel.Text = Title;
Alpha = 0.75f;
_activitySpinner.StartAnimating();
}
/// <summary>
/// Fades out the control and then removes it from the super view
/// </summary>
private void Hide()
{
_activitySpinner.StopAnimating();
Animate(
0.5, // duration
() => { Alpha = 0; },
() => { RemoveFromSuperview(); }
);
}
}
Any ideas?
UPDATE
My vm property looks like this
private bool _isBusy;
public bool IsBusy
{
get { return _isBusy; }
set { _isBusy = value; RaisePropertyChanged(() => IsBusy); }
}
It works fine in Android so I'm guessing the problem in not with that.

Answer 1

IsBusy is probably false at binding time. So _visible is set to false and Hide() is called. Now the view is removed from the superview and you can't show it anymore, because Show() doesn't add it to the superview again. Try to omit the RemoveFromSuperview();. Or modify the Visible property like this:
public bool Visible
{
get { return _visible; }
set
{
if(_visible == value)
return;
_visible = value;
if (_visible)
{
Show();
}
else
{
Hide();
}
}
}