的.cs

using System;
using System.Collections.Generic;

using Xamarin.Forms;

namespace LandAHand
{
    public partial class VolunteerView : ContentPage
    {
        public VolunteerView()
        {
            InitializeComponent();
            backgroundImage.Source = new UriImageSource
            {
                Uri = new Uri("https://s9.postimg.org/aq1jt3fu7/handshake_87122244_std.jpg"),CachingEnabled = true,CacheValidity = new TimeSpan(5,0)
            };
        }
    }
}

此代码成功使用iOS但不使用android.