As the error message says: DataBinding: 'myNameSpace.helper' does not contain a
property with the name 'NavigationUrl'.
Looking at the helper class this is also very correct.
public class helper
{
public string NavigationUrl, DisplayText;
public helper(string inputUrl, string inputText)
{
NavigationUrl = inputUrl;
DisplayText = inputText;
}
}
You need to convert NavigationUrl, DisplayText to properties instead of public variables.
Good luck!