FetchImage is a Swift package that makes it easy to download images using Nuke and display them in SwiftUI apps.
FetchImage is an observable object (ObservableObject) that allows you to manage the download of an image and observe the results of the download.
public final class FetchImage: ObservableObject, Identifiable { /// Returns the fetched image. /// /// - note: In case pipeline has `isProgressiveDecodingEnabled` option enabled /// and the image being downloaded supports progressive decoding, the `image` /// might be updated multiple times during the download. @Published public private(set) var image: PlatformImage? /// Returns an error if the previous attempt to fetch the most recent attempt /// to load the image failed with an error. @Published public private(set) var error: Error? /// Returns `true` if the image is being loaded. @Published public private(set) var isLoading: Bool = false /// The progress of the image download. @Published public var progress = Progress() }FetchImage doesn't ship an image view because it's trivial to create one using SwiftUI and customize it precisely the way you want.
An example of FetchImage usage in a custom SwiftUI view:
struct ImageView: View { let url: URL @StateObject private var image = FetchImage() var body: some View { ZStack { Rectangle().fill(Color.gray) image.view? .resizable() .aspectRatio(contentMode: .fill) .clipped() } .onAppear { image.load(url) } .onDisappear(perform: image.reset) } }Usage with a list:
struct DetailsView: View { @State var refresh: Bool = false var body: some View { List(imageUrls, id: \.self) { ImageView(url: $0) .frame(height: 200) } } }For iOS 13, use
@ObservedObject. WARNING:@ObservedObjectdoes not own the instance, you need to maintain the strong references to theFetchImageinstances somewhere else.
FetchImage gives you full control over how to manage the download and how to display the image. For example, one thing that you could do is to replace onAppear and onDisappear hooks to lower the priority of the requests instead of cancelling them. This might be useful if you want to continue loading and caching the images even if the user leaves the screen, but you still want the images the are currently on screen to be downloaded first.
.onAppear { self.image.priority = .normal self.image.fetch() // Restart the request if previous download failed } .onDisappear { self.image.priority = .low }Animations:
```swift struct ImageView: View { let url: URL @StateObject private var image = FetchImage() var body: some View { // ... create image view .onAppear { // Ensure that memory cache lookup is performed without animations withoutAnimation { image.load(url) } } .onDisappear(perform: image.reset) .animation(.default) } } private func withoutAnimation(_ closure: () -> Void) { var transaction = Transaction(animation: nil) transaction.disablesAnimations = true withTransaction(transaction, closure) }| Nuke | Swift | Xcode | Platforms |
|---|---|---|---|
| FetchImage | Swift 5.1 | Xcode 11.3 | iOS 13.0 / watchOS 6.0 / macOS 10.15 / tvOS 13.0 |
FetchImage is available under the MIT license. See the LICENSE file for more info.