Swift 3 URLSession memory leak

Question

I'm having memory leaks in my network calls for URLSession.shared in swift 3. Is this a bug or I am doing something wrong?

override func viewDidLoad() {
    super.viewDidLoad()
    let urlStr = "https://qrng.anu.edu.au/API/jsonI.php?length=10&type=hex16&size=2"
    URLSession.shared.dataTask(with: URL(string: urlStr)!) { data, response, error in
        self.view.backgroundColor = UIColor.red
        print(response)
    }.resume()
}

Answer 1

Shared URL session has a credential storage for cookies and other "browser" stuff. Since it's shared it is a singleton which will live forever in your application. Instruments interprets this as a leak.

Advice: repeat the action several times before you look for leaks.

Also, quite likely the self reference in your callback holds onto your view controller while your request is still pending. Use weak self at the block start to break the cycle. But that totally depends on your design. It got me at least in a few cases.

I also want to refer to this answer: https://stackoverflow.com/a/35757989/3351794