Xamarin.forms-区分后台和前台应用中心推送通知

Question

我已经看到了一些实现这一点的方法，但它们都是特定于平台的（本例中是iOS）。在PCL中是否有同样的方法？

Answer 1

我认为Xamarin Forms没有给出一个api来获取应用程序的状态。

可以通过在Xamarin.forms中使用dependencyservice来实现：

首先在PCL项目中定义接口：

public interface IGetAppState
{
    bool appIsInBackground();
}

[assembly: Dependency(typeof(GETAppState_iOS))]

namespace App129.iOS
{
    public class GETAppState_iOS : IGetAppState
    {
        public bool appIsInBackground()
        {
            UIApplicationState state = UIApplication.SharedApplication.ApplicationState;
            bool result = (state == UIApplicationState.Background);

            return result;
        }
    }
}

[assembly: Dependency(typeof(GETAppState_Android))]

namespace App129.Droid
{
    public class GETAppState_Android : IGetAppState
    {
        public bool appIsInBackground()
        {
            bool isInBackground;

            RunningAppProcessInfo myProcess = new RunningAppProcessInfo();
            GetMyMemoryState(myProcess);
            isInBackground = myProcess.Importance != Importance.Foreground;

            return isInBackground;
        }
    }
}

bool isInBackground = DependencyService.Get<IGetAppState>().appIsInBackground();