ZoomableScrollView no longer works in SwiftUI - swiftui

Question

Using Swift 5.5, Xcode 13.0, iOS 15.0.1,
Since Apple does not a good job on ScrollViews for SwiftUI (yet?), I had to implement my own zoomable ScrollView. See code below.
I had it successfully running for iOS13 and iOS14 - but now updating to iOS 15.0.1 I had to realise that it no longer works !
The error message is as follows:
objc[10882]: Cannot form weak reference to instance (0x1078d5540) of class _TtGC7SwiftUI19UIHostingControllerGVS_15ModifiedContentVS_5ImageVS_18_AspectRatioLayout__. It is possible that this object was over-released, or is in the process of deallocation.
dyld4 config: DYLD_LIBRARY_PATH=/usr/lib/system/introspection DYLD_INSERT_LIBRARIES=/Developer/usr/lib/libBacktraceRecording.dylib:/Developer/usr/lib/libMainThreadChecker.dylib:/Developer/Library/PrivateFrameworks/DTDDISupport.framework/libViewDebuggerSupport.dylib
(lldb)
I have everything inside a SwiftUIPager, and the problem occurs on the very last page when swiping. However, I don't think it is the Pagers fault since I can replace the ZoomableScrolView by a normal ImageView and everything works. Therefore I think Apple messed something up in their UIViewRepresentable. But maybe you can tell me more ??
Here is the entire code of my ZoomableScrolView:
import SwiftUI
struct ZoomableScrollView<Content: View>: UIViewRepresentable {
#Binding var didZoom: Bool
private var content: Content
init(didZoom: Binding<Bool>, #ViewBuilder content: () -> Content) {
_didZoom = didZoom
self.content = content()
}
func makeUIView(context: Context) -> UIScrollView {
// set up the UIScrollView
let scrollView = UIScrollView()
scrollView.delegate = context.coordinator // for viewForZooming(in:)
scrollView.maximumZoomScale = 20
scrollView.minimumZoomScale = 1
scrollView.bouncesZoom = true
// create a UIHostingController to hold our SwiftUI content
let hostedView = context.coordinator.hostingController.view!
hostedView.translatesAutoresizingMaskIntoConstraints = true
hostedView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
hostedView.frame = scrollView.bounds
hostedView.backgroundColor = .black
scrollView.addSubview(hostedView)
return scrollView
}
func makeCoordinator() -> Coordinator {
return Coordinator(hostingController: UIHostingController(rootView: self.content), didZoom: $didZoom)
}
func updateUIView(_ uiView: UIScrollView, context: Context) {
// update the hosting controller's SwiftUI content
context.coordinator.hostingController.rootView = self.content
assert(context.coordinator.hostingController.view.superview == uiView)
}
// MARK: - Coordinator
class Coordinator: NSObject, UIScrollViewDelegate {
var hostingController: UIHostingController<Content>
#Binding var didZoom: Bool
init(hostingController: UIHostingController<Content>, didZoom: Binding<Bool>) {
self.hostingController = hostingController
_didZoom = didZoom
}
func viewForZooming(in scrollView: UIScrollView) -> UIView? {
return hostingController.view
}
func scrollViewDidEndZooming(_ scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat) {
didZoom = !(scrollView.zoomScale == scrollView.minimumZoomScale)
}
}
}

Answer 1

I finally found a workaround.
Add the following code inside the ZoomableScrollView-UIViewRepresentable class:
static func dismantleUIView(_ uiView: UIScrollView, coordinator: Coordinator) {
uiView.delegate = nil
coordinator.hostingController.view = nil
}