Xamarin - 在导航后重新载入页面.PopModalAsync（）

Question

我使用Xamarin为iOS和Android创建应用程序，我有一个用例，我按下一个按钮，它将打开一个Modal，然后选择一个按钮后模式，它会更新一些信息，然后我需要弹出模态并重新加载它下面的主页面。这怎么可能？

主页：

public partial class MainPage : ContentPage 
{ 
    public MainPage(Object obj) 
    { 

     InitializeComponent(); 

     // do some things with obj... 

     BindingContext = this; 

    } 

    public ButtonPressed(object sender, EventArgs args) 
    { 
     Navigation.PushModalAsync(new SecondaryPage(newObj)); 
    } 

} 

次页面：

public partial class SecondaryPage : ContentPage 
{ 
    public SecondaryPage(Object newObj) 
    { 

     InitializeComponent(); 

     BindingContext = this; 

    } 

    public ButtonPressed(object sender, EventArgs args) 
    { 
     // Do something to change newObj 

     Navigation.PopModalAsync(); 
    } 

} 

打完PopModalAsync（），我需要能够调用的MainPage（）构造函数，但它传递了 “newObj”我在SecondaryPage中进行了更改。这甚至有可能吗？

Answer 1

的正确方法在.NET中做到这一点是建立一个事件：

public partial class SecondaryPage : ContentPage 
{ 
    public SecondaryPage(Object newObj) 
    { 

     InitializeComponent(); 

     BindingContext = this; 

    } 

    // Add an event to notify when things are updated 
    public event EventHandler<EventArgs> OperationCompeleted; 

    public ButtonPressed(object sender, EventArgs args) 
    { 
     // Do something to change newObj 
     OperationCompleted?.Invoke(this, EventArgs.Empty); 
     Navigation.PopModalAsync(); 
    } 

} 

public partial class MainPage : ContentPage 
{ 
    public MainPage(Object obj) 
    { 

     InitializeComponent(); 

     // do some things with obj... 

     BindingContext = this; 

    } 

    public ButtonPressed(object sender, EventArgs args) 
    { 
     var secondaryPage = new SecondaryPage(newObj); 
     // Subscribe to the event when things are updated 
     secondaryPage.OperationCompeleted += SecondaryPage_OperationCompleted; 
     Navigation.PushModalAsync(secondaryPage); 
    } 

    private void SecondaryPage_OperationCompleted(object sender, EventArgs e) 
    { 
     // Unsubscribe to the event to prevent memory leak 
     (sender as SecondaryPage).OperationCompeleted -= SecondaryPage_OperationCompleted; 
     // Do something after change 
    } 
}