C＃將C＃6.0轉換爲C＃4.0

Question

如何將C＃6.0代碼轉換爲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; 

我可以簡單地創建取得的財產？

Answer 1

你已經證明這種表達濃郁的方法僅僅是C＃6簡寫：

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