如何在将文本添加到 Xamarin Forms 中的条目之前加载视图

Question

I have a problem with OnAppearing function. I want to load the page first before adding the a text inside my entry. What is happening right now is that it is happening early meaning the text was inserted before the page has been loaded. Is there a way to solve this?

protected override async void OnAppearing()
{
    base.OnAppearing();
    entEncodedBy.Text = "Admin";
}

Answer 1

You can use any overloads of await Task.Delay(); to wait a long as you want and then change the text.

Or

You can use Device.StartTimer(TimeSpan, Func<Boolean>);

Answer 2

I not sure, but you can try add only await base.OnAppearing(); or you can just await Task.Run(()=>base.OnAppearing()); if this first method dont work.

Answer 3

A simple method is to use MessagingCenter , you can refer to the following code:

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();

        MessagingCenter.Subscribe<MainPage>(this, "Hi", async (sender) =>
        {
            await Task.Delay(2000); // 2000ms == 2s
            entEncodedBy.Text = "Admin";
        });
    }

    protected override  void OnAppearing()
    {
        base.OnAppearing();

        MessagingCenter.Send<MainPage>(this, "Hi");
    }
}

For more details, you can check: https://docs.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/messaging-center