How to utilize NSLock to prevent a function from firing twice?

Question

I current have a set of asynchronous functions that are both called in the viewDidLoad(). At the end of each function is a bool that is set from false to true u

Answer 1

Another approach using DispatchGroup. More simple, imho.

class ViewController: UIViewController {

    let group = DispatchGroup()

    override func viewDidLoad() {
        super.viewDidLoad()

        group.enter()
        functionOne()

        group.enter()
        functionTwo()

        group.notify(queue: .global(qos: .default), execute: { [weak self] in
            self?.functionThree()
        })
    }

    func functionOne() {
        //async stuff

        group.leave()
    }

    func functionTwo() {
        //async stuff

        group.leave()
    }

    func functionThree() {
        //stuff
    }
}