StorageUI with SwiftUI

[micheau-bastien]

StorageUI with SwiftUI

Description

I have been browsing to find SwiftUI Image Compatibility with FirebaseUI Storage and did not find anything that suited my need so I built a little helper class. This class syncs it's cache with UIKit existing StorageUI cache in order to avoid doubling the data consumption and cache size.

This work is heavily inspired from Ben McMahen's great article : https://benmcmahen.com/firebase-image-in-swiftui/

Feel free to reuse this !

Code

import Foundation
import SwiftUI
import FirebaseStorage
import SDWebImage
import FirebaseStorageUI

// TODO - Replace placeholder string to asset from your project
let placeholder = UIImage(named: "placeholder")!

/// SwiftUI View that will display placeholder, then Firebase Storage Image
struct StorageUIImage : View {

    /// Init
    /// - Parameter path: firebase path of the image (ex.: "storageFolder/subfolder/filename.jpg")
    init(path: String) {
        self.imageLoader = LiveLoader(path)
    }

    /// Image Loader observed object that will trigger image changes.
    @ObservedObject private var imageLoader: LiveLoader

    var body: some View {
        Image(uiImage: imageLoader.image ?? placeholder)
    }
}

/// LiveLoader class that will try to return image from memory cache, then disk cache, then network.
final class LiveLoader : ObservableObject {
    /// Published image object to be observed
    @Published var image: UIImage? = nil

    init(_ path: String){
        let storage = Storage.storage()
        let ref = storage.reference().child(path)
        let url = NSURL.sd_URL(with: ref) as? URL
        if let image = SDImageCache.shared.imageFromCache(forKey: SDWebImageManager.shared.cacheKey(for: url)) {
            // If image was present form memory cache, we display it
            print("Image loaded from memory cache")
            self.image = image
        } else if let image = SDImageCache.shared.imageFromDiskCache(forKey: SDWebImageManager.shared.cacheKey(for: url)) {
            // Else if image was present form disk cache, we cache it in memory again and display it
            print("Image loaded from disk cache")
            SDImageCache.shared.store(self.image, forKey: SDWebImageManager.shared.cacheKey(for: url), toDisk: false) {
                self.image = image
            }
        } else {
            // Else we fetch it from network, cache it in memory and disk, then display it
            print("Image downloaded")
            // maxSize can be set as parameter if needed
            ref.getData(maxSize: 1 * 1024 * 1024) { data, error in
                if let error = error {
                    print("\(error)")
                }
                guard let data = data else { return }
                SDImageCache.shared.store(self.image, forKey: SDWebImageManager.shared.cacheKey(for: url)) {
                    DispatchQueue.main.async {
                        self.image = UIImage.init(data: data)
                    }
                }
            }
        }
    }
}

Open points

• Usage of @StateObject instead of @ObservableObject
• Real testing of the load from disk without cache present was not done
• Operators like .resizable()don't work on StorageUIImage view

[micheau-bastien]

Linked to #811 that covers other FirebaseUI's parts in SwiftUI

[morganchen12]

Thanks @micheau-bastien! Would you like to contribute this as a PR?