Crash on iOS + MacOS with 100.12

Question

I want to store the viewpoint from the viewpointChanged signal. This works well on PC & Android, but crashes on MacOS and iOS. Actually the crash is intermittent on iOS.

Starting from the QML template, add the following in the MapView:

onViewpointChanged: {           
    let point = GeometryEngine.project(mapView.screenToLocation(width / 2, height / 2), Factory.SpatialReference.createWgs84())           
    //point.x // Weird hack which fixes crash on MacOS/iOS           
    let viewpoint =  ArcGISRuntimeEnvironment.createObject("ViewpointCenter", {center: point, targetScale: mapView.mapScale})           
    console.log(viewpoint.json)       
}

Note that if I uncomment the "point.x", then the crash goes away.

mapbug.zip

JamesBallard1 · Answer

@JustinSteventon sorry for the delay. I will log an internal issue for the team to keep looking into this. In the meantime I encourage you to open an official support request.

JustinSteventon · Answer

@JamesBallard1 the line that faults consistently is the last one in your snippet, i.e. containing "console.log(viewpoint.json)".

Note, that the snippet misses a log line after the 'viewpoint' creation, but before referencing 'viewpoint.json'. So it seems that the issue is related to creating the json for the ViewpointCenter object.

My repro is 100%, but as soon as I add that "point.x" line, I can no longer repro. The repro is 100% only on MacOS and is less consistent on iOS. However, my app was rejected from the iOS Appstore due to this crash, so it is not just my machine.

I am not blocked, but this kind of bug is a bit worrying. I am not very familiar with MacOS debug symbols, but if you would like to walk me through adding them so you can get a better stack, then I would be happy to help.

JamesBallard1 · Answer

@JustinSteventon, thanks for the extra info.

I still cannot reproduce the problem on my end. One of my colleagues attempted and also couldn't reproduce it.

The stack trace is limited, so hard to tell from that. Are you able to determine which call is the culprit that's crashing? I can see in the stack it's getting into our Runtime library, but that's all.

Hopefully it's not a Heisenbug that suddenly works fine after you alter the code with some logging.

For example, does this code point to a particular function that's crashing?

onViewpointChanged: {
    console.log("screenToLocation");
    let screenToLocation = mapView.screenToLocation(width / 2, height / 2);
    console.log("Factory.SpatialReference.createWgs84()");
    let sr = Factory.SpatialReference.createWgs84();
    console.log("GeometryEngine.project");
    let point = GeometryEngine.project(screenToLocation, sr);
    console.log("ArcGISRuntimeEnvironment.createObject");
    let viewpoint = ArcGISRuntimeEnvironment.createObject("ViewpointCenter", {center: point, targetScale: mapView.mapScale})
    console.log(JSON.stringify(viewpoint.json))
}