how to use UIViewRepresentable Coordinator delegate - swift

Question

I'm using Pulley a maps drawer library which is written in UIKit in a SwiftUI project. I have a SwiftUI ListView that I'm using in the project via a UIHostingController but I want to disable scrolling when the drawers position is not open and to do that I'm pretty sure I need to use one of the delegate functions Pulley provides (drawerPositionDidChange) but I'm not sure how to use the delegate in the Coordinator or if I should even try to use the delegate, maybe I just need to use some type of state variable?
Delegate in the view controller
#objc public protocol PulleyDelegate: AnyObject {
/** This is called after size changes, so if you care about the bottomSafeArea property for custom UI layout, you can use this value.
* NOTE: It's not called *during* the transition between sizes (such as in an animation coordinator), but rather after the resize is complete.
*/
#objc optional func drawerPositionDidChange(drawer: PulleyViewController, bottomSafeArea: CGFloat)
}
This is the UIViewRepresentable where I'm trying to use the delegate.
import SwiftUI
struct DrawerPosition: UIViewControllerRepresentable {
#Binding var bottomSafeArea: CGFloat?
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
func makeUIViewController(context: Context) -> some UIViewController {
let vc = PulleyViewController()
vc.delegate = context.coordinator
return vc
}
func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
// Updates the state of the specified view controller with new information from SwiftUI.
}
class Coordinator: NSObject, PulleyDrawerViewControllerDelegate {
var parent: DrawerPosition
init (_ parent: DrawerPosition) {
self.parent = parent
}
func drawerPositionDidChange(drawer: PulleyViewController, bottomSafeArea: CGFloat){
self.parent.bottomSafeArea = bottomSafeArea
}
}
}
the ListView where I want to disable the scroll.
import SwiftUI
struct ListView: View {
#State private var bottomSafeArea: CGFloat?
var body: some View {
ScrollViewReader { proxy in
VStack {
Button("Jump to #50") {
proxy.scrollTo(50)
}
List(0..<100, id: \.self) { i in
Text("Example")
.id(i)
}.scrollDisabled(bottomSafeArea == 0 ? true : false)
}
}
}
}
class ListViewVHC: UIHostingController<ListView> {
required init?(coder: NSCoder) {
super.init (coder: coder, rootView: ListView())
}
}
struct ListView_Previews: PreviewProvider {
static var previews: some View {
ListView()
}
}

Answer 1

Here is the correct way to set up a Coordinator:
func makeCoordinator() -> Coordinator {
Coordinator()
}
func makeUIViewController(context: Context) -> PullyViewController {
context.coordinator.pullyViewController
}
func updateUIViewController(_ uiViewController: PullyViewController, context: Context) {
// Updates the state of the specified view controller with new information from SwiftUI.
context.coordinator.bottomSafeAreaChanged = { bottomSafeArea in
self.bottomSafeArea = bottomSafeArea
}
}
class Coordinator: NSObject, PulleyDrawerViewControllerDelegate {
lazy var pullyViewController: PulleyViewController = {
let vc = PulleyViewController()
vc.delegate = self
return vc
}()
var bottomSafeAreaChanged: ((CGFloat) -> Void)?
func drawerPositionDidChange(drawer: PulleyViewController, bottomSafeArea: CGFloat){
bottomSafeAreaChanged?(bottomSafeArea)
}