Xamarin：如何从iOS库项目加载图像

Question

I have a Xamarin Project styled with MvvmCross. There are Subprojects:

• Core (PCL)
• ViewModel (PCL)
• iOS (Executable)

If i add an image to my iOS project (Resoureces/Images/test_image.png), then i can load it with this code:

UIImage image = UIImage.FromBundle("Images/test_icon.png");

Now, i want to use a new Subproject

• Controls (iOS Library)

This library should load an image. I added an image to Controls (Resoureces/Images/test_image.png)

But i can not load this image in Controls proj.

My Question: How to load images from iOS libraries?

    public class MyButton : UIButton
    {
        public MyButton () : base()
        {
            Initialize ();
        }

        void Initialize()
        {
            // load image from bundle
            UIImage image = UIImage.FromBundle("Images/test_icon.png");
            // image is null
            this.SetImage (image, UIControlState.Normal);
        }
    }

and the ViewController class is :

    public partial class FirstView : MvxViewController
    {
        public FirstView () : base ("FirstView", null)
        {
        }

        public override void ViewDidLoad ()
        {
            base.ViewDidLoad ();

            // load image from bundle
//          UIImage image = UIImage.FromBundle("Images/test_icon.png");
//          image is not null if added in iOS Proj
//          this.imageView.Image = image;

            MyButton button = new MyButton ();

            View.Add (button);

            View.AddConstraint (NSLayoutConstraint.Create (button, NSLayoutAttribute.Right, NSLayoutRelation.Equal, View, NSLayoutAttribute.Right, 1, 10));
            View.AddConstraint (NSLayoutConstraint.Create (button, NSLayoutAttribute.Top, NSLayoutRelation.Equal, View, NSLayoutAttribute.Top, 1, 74));
            View.AddConstraint (NSLayoutConstraint.Create (button, NSLayoutAttribute.Width, NSLayoutRelation.Equal, null, NSLayoutAttribute.NoAttribute, 0, 64)); 
            View.AddConstraint (NSLayoutConstraint.Create (button, NSLayoutAttribute.Height, NSLayoutRelation.Equal, null, NSLayoutAttribute.NoAttribute, 0, 64)); 
        }
    }

Here is full proj: https://bitbucket.org/ww_wschaefer/xamarin-first-crossover-app/overview

Answer 1

A little explanation on my comment.

You have to change

UIImage image = UIImage.FromBundle("Images/test_icon.png");

to

UIImage image = UIImage.FromFile("Images/test_icon.png");

As the image is not added as bundled resource.

The UIImage.FromFile() method loads the image asynchronously. It also allows the application to load the image from an external location .

Unlike the UIImage.FromFile() method, the UIImage.FromBundle() method is a blocking call and only loads images from within the application bundle . However, it caches the images after loading it.

For further understanding have a look at the book - Developing C# Apps for iPhone and iPad using MonoTouch