Trouble to make a custom UIView aspect scale fit/fill with SwiftUI - swiftui

Question

No Public API in SwiftUI to response for the resizable modifier of View protocol. Only Image in SwiftUI could work with .resizable(). Custom UIView like UIView for GIF is not resizable now.
I use SDWebImageSwiftUI AnimatedImage, which is backing UIKit View SDAnimatedImageView. AnimatedImage is not response to .resizable(), .scaleToFit, .aspectRatio(contentMode: .fit), etc. WebImage is backing SwiftUI Image, so it's working fine.
import SwiftUI
import SDWebImageSwiftUI
struct ContentView: View {
let url = URL(string: "https://media.giphy.com/media/H62DGtBRwgbrxWXh6t/giphy.gif")!
var body: some View {
VStack {
AnimatedImage(url: url)
.scaledToFit()
.frame(width: 100, height: 100)
WebImage(url: url)
.scaledToFit()
.frame(width: 100, height: 100)
}
}
}
Not sure if it's an Apple bug. Expect custom view like SDWebImageSwiftUI AnimatedImage is responsive to SwiftUI size related modifiers like .scaledToFit().
Related issue: https://github.com/SDWebImage/SDWebImageSwiftUI/issues/3

Answer 1

SwiftUI uses the compression resistance priority and the content hugging priority to decide what resizing is possible.
If you want to resize a view below its intrinsic content size, you need to reduce the compression resistance priority.
Example:
func makeUIView(context: Context) -> UIView {
let imageView = UIImageView(image: UIImage(named: "yourImage")!)
imageView.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
imageView.setContentCompressionResistancePriority(.defaultLow, for: .vertical)
return imageView
}
This will allow you to set .frame(width:height:) to any size you want.

Answer 2

Finally found a solution.
Make a UIView wrapper outside of the SDAnimationImageView or UIImageView, then override layoutSubviews() set the frame of subview.
Here is full code by me.
And SDWebImageSwiftUI also release a new version which uses wrapper to solve this problem.
class ImageModel: ObservableObject {
#Published var url: URL?
#Published var contentMode: UIView.ContentMode = .scaleAspectFill
}
struct WebImage: UIViewRepresentable {
#ObservedObject var imageModel = ImageModel()
func makeUIView(context: UIViewRepresentableContext<WebImage>) -> ImageView {
let uiView = ImageView(imageModel: imageModel)
return uiView
}
func updateUIView(_ uiView: ImageView, context: UIViewRepresentableContext<WebImage>) {
uiView.imageView.sd_setImage(with: imageModel.url)
uiView.imageView.contentMode = imageModel.contentMode
}
func url(_ url: URL?) -> Self {
imageModel.url = url
return self
}
func scaledToFit() -> Self {
imageModel.contentMode = .scaleAspectFit
return self
}
func scaledToFill() -> Self {
imageModel.contentMode = .scaleAspectFill
return self
}
}
class ImageView: UIView {
let imageView = UIImageView()
init(imageModel: ImageModel) {
super.init(frame: .zero)
addSubview(imageView)
}
override func layoutSubviews() {
super.layoutSubviews()
imageView.frame = bounds
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}