How to access application delegate from SDK on iOS?

I'm trying to access an application delegate from SDK that does not know the class name of the application delegate. I mean that my SDK doesn't know what class will be an application delegate in a basic project. So I find a class that conforms to the protocol UIApplicationDelegate.

    let numberOfClasses: UnsafeMutablePointer<UInt32> = UnsafeMutablePointer<UInt32>.alloc(0)
    let classes = objc_copyClassList(numberOfClasses)
    var appDelegateClass: AnyClass? = nil

    for i in 0...Int(numberOfClasses.memory) {
        if class_conformsToProtocol(classes[i], UIApplicationDelegate.self) {
            appDelegateClass = classes[i]
        }
    }

But the result has "type" "AnyClass?". The following code results getting an error "'applicationDelegateClass' is not a type":

    if let applicationDelegateClass = appDelegateClass {
        if let delegate = UIApplication.sharedApplication().delegate as? applicationDelegateClass.self { }
    }

How could I solve it?

I actually shouldn't use the specific application delegate class. The right code:

if let delegate = UIApplication.sharedApplication().delegate! as? UIApplicationDelegate {}