hossamghareeb

// No memberwise initializer
struct Player {
    let name: String
    var score: Int = 0
    init(json: [String: AnyObject]) {

    }
}

// you have the both initializers:

hossamghareeb

Remove @main or @UIApplicationMain

hossamghareeb

// Assuming you use one storyboard per view controller 

extension UIViewController {
    
    static func fromStoryboard() -> Self {
        let name = String(describing: Self.self)
        let sb = UIStoryboard(name: name, bundle: nil)
        return sb.instantiateViewController(identifier: name) as! Self
    }
}

hossamghareeb

class Singleton {
    private static var instance = Singleton()
    #if DEBUG
    static var stubbedInstance: Singleton?
    #endif
    
    static var shared: Singleton {
        #if DEBUG
        if let stubbedInstance = stubbedInstance { return stubbedInstance }
        #endif

hossamghareeb

class ViewController {
    var manager: Singleton {
        return Singleton.shared
    }
}

// in unit testing target
class TestingViewController: ViewController {
    override var manager: Singleton { Singleton() }
}