Frequent custom control and converter problems

Most of the issues that arise when working with custom controls regularly have to do with bindable properties. Often, a small typo or a little oversight might cause your custom control to not react as expected or to display the wrong data.

Troubleshooting bindable properties

On a custom control, there is a lot of ceremony needed to define bindable properties. It’s very easy to make a mistake that is very hard to spot when troubleshooting. Here are a couple of things to look out for:

• The propertyName parameter in the Create method: Make sure the propertyName parameter matches the exact naming of the property:

  public static readonly BindableProperty
    IsFavoriteProperty =
      BindableProperty.Create(nameof(IsFavorite), …);
  public bool IsFavorite
  {
      ...
  }

  As this code sample shows, it is advised to use the nameof expression to prevent typos!

• The returnType parameter...