Xamarin.Forms SystemFontOfSize缺少一些重载

Question

According to Xamarin.Forms documentation , I should be able to set font attributes using Font.SystemFontOfSize([size], [FontAttributes]) method. But when I create a new Blank App (Xamarin.Forms Portable) project and add the following code to App.cs in the portable project, for some reason I don't have access to all of the overloads for Font.SystemFontOfSize(...) and no access to Xamarin.Forms.FontAttributes enum.

// FontExample/App.cs
using System;
using Xamarin.Forms;
namespace FontExample {
    public class App {
        public static Page GetMainPage() {
            return new ContentPage {
                Content = new Label {
                    Text = "Hello, Forms !",
                    Font = Font.SystemFontOfSize(14, FontAttributes.Italic)
                },
            };
        }
    }
}

There seem to be only two overloads of SystemFontOfSize and the compiler gives me:

The name 'FontAttributes' does not exist in the current context [...]

The project seem to have all the default references in place (.NET, Xamarin.Forms.Core, Xamarin.Forms.Xaml), I did not touch them.

But, if I download a sample project with exactly the same setup (calling Font.SystemFontOfSize from within the portable project with the same references), the project compiles fine and I seem to have access to all of the Font.SystemFontOfSize overloads as well as the Xamarin.Forms.FontAttributes enum.

Why don't I have access to all Xamarin.Forms API features when creating a new project myself? I can't find any significant difference between the newly created Blank App (Xamarin.Forms Portable) and the sample project linked above.

Answer 1

It sounds like your build is getting confused somewhere.

Try removing the Xamarin.Forms references via NuGet ; close-down the project and re-open; re-add Xamarin.Forms via NuGet . The current latest version should be like v1.2.3x.

If the above approach doesn't work, try doing a clean build (In Visual Studio, Build -> Clean Solution') and then try to rebuild.

As a final resort go into each application folder and delete the 'obj' and 'bin' directories and rebuild.

One of the above should resolve your issue.

Note - however that there is an issue with using Font.SystemFontOfSize({fontsize}, {font-attributes-enum}) , in a previous version of Xamarin.Forms that would cause this overload to crash the application with an exception .

Unless they have now corrected this you will need to use something like Font.SystemFontOfSize(30).WithAttributes(FontAttributes.Bold) instead to get around this.