Windows Phone App data

Question

我想做的是我想在我的应用程序中为我的用户维护个人资料图片。用户可以从本地图片库中进行图片分析。 因此，每当应用程序加载时，它都应该检查本地应用程序数据是否存在图片，如果存在，则应将图像设置为该图片。 我尝试这样做，但它不起作用。

// Saving
BitmapImage bitmapImage = image.Source as BitmapImage;
Windows.Storage.ApplicationDataContainer localSettings = Windows.Storage.ApplicationData.Current.LocalSettings;
string path = bitmapImage.UriSource.ToString();
localSettings.Values["ProfilePic"] = path;
// In constructor retrieving like this.
string sourceVal = localSettings.Values["ProfilePic"] as string;
if (sourceVal != null) {
    Image img = new Image();
    BitmapImage bi = new BitmapImage();
    Uri uri = new Uri(sourceVal);
    bi.UriSource = uri;
    img.Source = bi;
}

它抛出异常，任何人都可以使用 C# 给他们适当的代码吗？

System.NullReferenceException发生了。

Answer 1

在这里和那里修改了你的代码，它对我来说工作正常。看一看

XAML

    <Image Name="img" Height="100" Width="100"/>

代码隐藏：

// define on top
Windows.Storage.ApplicationDataContainer localSettings = Windows.Storage.ApplicationData.Current.LocalSettings;

//in constructor or in OnNavigatedTo()
 string sourceVal = localSettings.Values["ProfilePic"] as string;
 if (sourceVal != null)
        {
            //  Image img1 = new Image();
            BitmapImage bi = new BitmapImage();
            Uri uri = new Uri(sourceVal, UriKind.Relative);
            bi.UriSource = uri;
            img.Source = bi;
        }
        else
        {
            // hardcoding image source for testing. You can set image here from gallery
            img.Source = new BitmapImage(new Uri("/Assets/AlignmentGrid.png", UriKind.Relative));
        }
// Save image (in OnNavigatedFrom())
BitmapImage bitmapImage = img.Source as BitmapImage;
string path = bitmapImage.UriSource.ToString();
localSettings.Values["ProfilePic"] = path;

试试这个，如果有任何问题，请告诉我。