App freezes when trying to dismiss a popup in a sheet

[zkline101]

I have an iOS app that is showing a popup in a sheet and when I try to dismiss that sheet by swiping down the whole app freezes and I see the memory starts to increase without stopping.

I have a reproducer for this that I can send if that helps.

[zkline101]

I am using an iOS 18.2 simulator, Xcode 16.2 and I am using the Toolkit branch OfflineMapAreasView and I am using 200.6 of the SDK.

[zkline101]

In my app, if I remove the scale bar from the app then this problem doesn't occur. This could be an iOS bug but not sure. It seems like if I have some toolkit components overlaid on my map then I show a popup in a sheet and I try to swipe to dismiss the sheet then it freezes.

[dfeinzimer]

Interestingly, not a problem with a floating panel, just sheets.

Reproducer

import ArcGIS
import ArcGISToolkit
import SwiftUI

struct PopupExampleView: View {
    static func makeMap() -> Map {
        let portalItem = PortalItem(
            portal: .arcGISOnline(connection: .anonymous),
            id: Item.ID("9f3a674e998f461580006e626611f9ad")!
        )
        return Map(item: portalItem)
    }
    
    /// The height of the map view's attribution bar.
    @State private var attributionBarHeight: CGFloat = 0
    
    /// The `Map` displayed in the `MapView`.
    @State private var map = makeMap()
    
    /// The point on the screen the user tapped on to identify a feature.
    @State private var identifyScreenPoint: CGPoint?
    
    /// The popup to be shown as the result of the layer identify operation.
    @State private var popup: Popup? {
        didSet { showPopup = popup != nil }
    }
    
    /// A Boolean value specifying whether the popup view should be shown or not.
    @State private var showPopup = false
    
    /// The detent value specifying the initial `FloatingPanelDetent`.  Defaults to "full".
    @State private var floatingPanelDetent: FloatingPanelDetent = .full
    
    private let alignment: Alignment = .bottomLeading
    private let maxWidth: Double = 175.0
    @State private var spatialReference: SpatialReference?
    @State private var unitsPerPoint: Double?
    @State private var viewpoint: Viewpoint?
    
    var body: some View {
        MapViewReader { proxy in
            MapView(map: map)
                .onSpatialReferenceChanged { spatialReference = $0 }
                .onUnitsPerPointChanged { unitsPerPoint = $0 }
                .onViewpointChanged(kind: .centerAndScale) { viewpoint = $0 }
                .onAttributionBarHeightChanged {
                    attributionBarHeight = $0
                }
                .onSingleTapGesture { screenPoint, _ in
                    identifyScreenPoint = screenPoint
                }
                .task(id: identifyScreenPoint) {
                    guard let identifyScreenPoint else { return }
                    let identifyResult = try? await proxy.identifyLayers(
                        screenPoint: identifyScreenPoint,
                        tolerance: 10,
                        returnPopupsOnly: true
                    ).first
                    popup = identifyResult?.popups.first
                }
                .overlay(alignment: alignment) {
                    Scalebar(
                        maxWidth: maxWidth,
                        spatialReference: spatialReference,
                        unitsPerPoint: unitsPerPoint,
                        viewpoint: viewpoint
                    )
                    .padding(.horizontal, 10)
                    .padding(.vertical, 10 + attributionBarHeight)
                }
                .sheet(
                    isPresented: $showPopup
                ) { [popup] in
                    PopupView(popup: popup!, isPresented: $showPopup)
                        .padding()
                }
        }
    }
}

[rolson]

This is bad bug affecting the epic app and other dev summit demos.

[mhdostal]

It does seem like SwiftUI is struggling with the Scalebar. I got it to freeze with @dfeinzimer 's reproducer. Breaking in the debugger produce the results below (this is just a representative sample, not all of them):

I have not been able to reproduce with either the Compass or OverviewMap components in an overlay, just the Scalebar.

Is removing the scalebar an acceptable solution for now? I suspect it will take some time to diagnose the issue with the Scalebar and (probably) attempt to simplify it.

[dfeinzimer]

This seems possibly related to #802.

Another workaround would be to remove the Scalebar from the hierarchy while the sheet is presented.

.overlay {
    if !sheetIsPresented {
        Scalebar(
            ...
        )
    }
}

[rolson]

I tried that in my app and it never came back... strange. Yes, probably best to just remove scalebar.

cc @nixta

[dfeinzimer]

Well, this is weird. Using overlay(alignment:content:) vs overlay(content:) seems to make all the difference. The alignment is throwing something off somehow. I've distilled the reproducer down to this:

import ArcGIS
import ArcGISToolkit
import SwiftUI

struct PopupExampleView: View {
    let map = Map(basemapStyle: .arcGISCommunity)
    
    @State private var showPopup = false
    
    @State private var spatialReference: SpatialReference?
    @State private var unitsPerPoint: Double?
    @State private var viewpoint: Viewpoint?
    
    var body: some View {
        MapView(map: map)
            .onSpatialReferenceChanged { spatialReference = $0 }
            .onUnitsPerPointChanged { unitsPerPoint = $0 }
            .onViewpointChanged(kind: .centerAndScale) { viewpoint = $0 }
            .onSingleTapGesture { _, _ in
                showPopup = true
            }
            .overlay {                          // <=== NO FREEZE
//            .overlay(alignment: .bottomLeading) { // <=== FREEZES
                Scalebar(
                    maxWidth: 175,
                    spatialReference: spatialReference,
                    unitsPerPoint: unitsPerPoint,
                    viewpoint: viewpoint
                )
            }
            .sheet(isPresented: $showPopup) { }
    }
}

[rolson]

Wow, nice! We can work with that. Great find.