Question

I have BackButton that inherits UIButton.
It doesn’t have a xib, is pretty simple and contains some layout logic which I omit.

Here is how I declared it:

[Register("BackButton")]
public class BackButton : UIButton
{
    public BackButton (string text, EventHandler handler)
        : base (UIButtonType.Custom)
    {
        TouchUpInside += handler;
        SetTitle (text, UIControlState.Normal);
    }

    public BackButton(IntPtr handle) : base(handle) { }
}

If I use BackButton in another view’s xib, its underlying class is seen as BackButton:

However, when I create an instance from code, the underlying class is just UIButton:

This is frustrating because I’m trying to use UIAppearance for this class and I need it to be the right instance.

What’s the problem?

Answer 1

Turns out, I had to call the parameterless UIButton constructor, and not the one I was calling.
Removing : base (UIButtonType.Custom) from constructor defnition was enough to make it work:

public BackButton (string text, EventHandler handler)
     // : base (UIButtonType.Custom) -- remove this line
{
    TouchUpInside += handler;
    SetTitle (text, UIControlState.Normal);
}

In hindsight, this makes perfect sense because UIButton(UIButtonType) constructor provided by MonoTouch actually calls [UIButton buttonWithType:]:

public UIButton (UIButtonType type) : base (
    Messaging.IntPtr_objc_msgSend_int (UIButton.class_ptr,
        UIButton.selButtonWithType_, (int)type)
    ) { }

There is no way, I presume, for [UIButton buttonWithType:] to know about my custom view so it just creates a UIButton.