Snapshotting a `UIView` crashes the app with `NSInvalidArgumentException` "[_UIReplicantView _isSymbolImage]: unrecognized selector sent to instance" - swift

Question

Hi guys i have just updated XCode to version 11.4 from the app store and when i try to snapshot a UIView on iOS 13.4 like this:
extension UIView {
func snapshot(at scale: CGFloat) -> UIImage? {
let renderer = UIGraphicsImageRenderer(size: bounds.size)
let image = renderer.image { [weak self] context in
self?.drawHierarchy(in: self?.bounds ?? .zero, afterScreenUpdates: true)
}
return image
}
}
or like that:
extension UIView {
func snapshotOld(at scale: CGFloat) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(bounds.size, false, scale)
guard let currentContext = UIGraphicsGetCurrentContext() else { return nil }
layer.render(in: currentContext)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
}
and set the resulting image to UIImageView like that:
class ViewController: UIViewController {
#IBOutlet private weak var imageView: UIImageView!
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
let image = view.snapshot
imageView.image = image
}
}
extension UIView {
#objc var snapshot: UIImage? {
snapshot(at: 3.0)
// snapshotOld(at: 3.0)
}
}
i get:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[_UIReplicantView _isSymbolImage]: unrecognized selector sent to instance 0x115907c00'
*** First throw call stack:
(0x1ad52c164 0x1ad240c1c 0x1ad42a7e0 0x1b16a5b6c 0x1ad53085c 0x1ad532b60 0x1b1af6cdc 0x1b1af714c 0x1b1af0b30 0x1025061a8 0x102506270 0x1b1010880 0x1b10112cc 0x1b0f25658 0x1b167fc10 0x1b166f13c 0x1b16a088c 0x1ad4a6c54 0x1ad4a18e4 0x1ad4a1d84 0x1ad4a1660 0x1b78b2604 0x1b167615c 0x102507f78 0x1ad31d1ec)
libc++abi.dylib: terminating with uncaught exception of type NSException
I get this both in simulator and on a real device.
Do you guys have any idea why is this happening? I suspect it is a XCode 11.4 bug because this code worked nicely on the older versions 🤔
Here is a sample project if you would like to try it out on your machine

Answer 1

You're not calling the method you think you are. You have two choices:
Change snapshot to snapshott everywhere (or some other nonambiguous alternative).
Or else, remove the #objc designation.
Do either of those things, and all will be well.