How can I save a SwiftUI image to disk or get the data out?

Question

I'm trying to save a SwiftUI image (not a UIImage from UIKit) to disk.

I've looked everywhere but could not find any documented information on how to do this. I also cannot see a way to extract the Data from the SwiftUI image.

Can anybody help? Thanks in advance.

possible easy way -> https://stackoverflow.com/questions/65614931/uploading-an-image-instead-of-an-uiimage-to-firestore/65616306#65616306 — Yodagama, Jan 08 '21 at 00:41

score 6 · Accepted Answer · answered Aug 11 '19 at 06:46

With SwiftUI, things work a little differently. What you want to do, cannot be done in that fashion. Instead, you need to look at how the image was created and obtain the image data from the same place that your Image() got it in the first place.

Also if you need the actual binary data to save it to disk, you need a UIImage (note that I am not saying UIImageView).

Fortunately, Image can handle UIImage too, check this other question for that: https://stackoverflow.com/a/57028615/7786555

Exactly, SwiftUI's `Image()` is actually a view showing some image (cgImage, UIImage, loaded from disk, etc). — Vlad Lego, Aug 11 '19 at 07:58

score 2 · Answer 2 · answered Oct 15 '20 at 05:46

I convert the SwiftUI image to UIImage then save it to UserDefaults.

It's not the best solution, but I didn't find better one:

   // reading the saved image from userDefaults
   private func getSavedImage(for size: String) -> Image? {
    if let data = UserDefaults.standard.data(forKey: size) {
        if let image = UIImage(data: data) {
            return Image(uiImage: image)
        }
    }
    return nil
  }



// Converting SwiftUI Image to UIImage
extension View {

    public func toUIImage() -> UIImage {

        let controller = UIHostingController(rootView: self)
        controller.view.frame = CGRect(x: 0, y: CGFloat(Int.max), width: 1, height: 1)
        #if targetEnvironment(macCatalyst)

            UIApplication.shared.windows.first!.rootViewController?.view.addSubview(controller.view)

        #else

        var window: UIWindow? {
            guard let scene = UIApplication.shared.connectedScenes.first,
                  let windowSceneDelegate = scene.delegate as? UIWindowSceneDelegate,
                  let window = windowSceneDelegate.window else {
                return nil
            }
            return window
        }

        if let window = window, let rootViewController = window.rootViewController {
                var topController = rootViewController
                while let newTopController = topController.presentedViewController {
                    topController = newTopController
                }
            topController.view.insertSubview(controller.view, at: controller.view.subviews.count)
        } else {
            print("cant access window")
        }

        #endif

        let size = controller.sizeThatFits(in: UIScreen.main.bounds.size)
        controller.view.bounds = CGRect(origin: .zero, size: size)
        controller.view.sizeToFit()

        // here is the call to the function that converts UIView to UIImage: `.asImage()`
        let image = controller.view.toUIImage()
        controller.view.removeFromSuperview()
        return image
    }
}

Using the top helper & save the image:

extension Image {
    
func toData()-> Data {
    return self.toUIImage().jpegData(compressionQuality: 1)!
}

func save(for name: String) {
        UserDefaults.standard.setValue(self.toData(), forKey: name)
    }
}

Just to note: This solution uses "UIApplication.shared.windows.first!.rootViewController?" which is not appropriate anymore. — Hardy, Sep 24 '21 at 14:32

How can I save a SwiftUI image to disk or get the data out?

2 Answers2