C＃将C＃6.0转换为C＃4.0

Question

如何将此C＃6.0代码转换为C＃4.0？

public void Subscribe(string message, Action<IMessagingService> callback) =>
            MessagingCenter.Subscribe<MessagingService>(this, message, callback);

或

public object ConvertBack(object value, Type targetType, object parameter, 
                          CultureInfo culture) => null;

我可以简单地创建get属性吗？

Answer 1

你所展示的这种表达方式只是C＃6的简写：

public void Subscribe(string message, Action<IMessagingService> callback)
{
    MessagingCenter.Subscribe<MessagingService>(this, message, callback);
}