I faced the same error in a different context, in XCode 12.0.1 too. It might not be related, but I suspect its an issue with accessing the run loop of the main thread. I was just trying out some introductory code I found online, and faced the same issue, so this is a bug, rather than a problem with your code. Here’s how you can get a piece of code that has the same issue:
git clone [email protected]:BestKora/CS193P-Fall-2017-Demo-iOS12.git cd "CS193P-Fall-2017-Demo-iOS12/Cassini L10" xed . # this opens XCode (CLI tool stands for XCode editor)
Having said that, by rewriting the code, I was able to prevent this issue. Maybe you can find something amongst the code below to fix your specific issue:
Specifically, instead of using the following (DispatchQueue.global
)
private func fetchImage() { if let url = imageURL { spinner.startAnimating() DispatchQueue.global(qos: .userInitiated).async { [weak self] in let urlContents = try? Data(contentsOf: url) DispatchQueue.main.async { if let imageData = urlContents, url == self?.imageURL { self?.image = UIImage(data: imageData) } } } } }
I use URLSession.shared.dataTask
, and this error no longer happens:
private func fetchImage() { print("fetching image") if let url = imageURL { let task = URLSession.shared.dataTask(with: url) {(data, response, error) in guard let data = data else { return } // maybe try dispatch to main DispatchQueue.main.async { self.imageView.image = UIImage(data: data) } } task.resume() } }