在多个Swift类上具有相同的扩展名

Question

I have this in my appDelegate and was wondering how to make this into one extension?

extension UIViewController {
    var appDelegate:AppDelegate {
        return UIApplication.sharedApplication().delegate as! AppDelegate
    }
}

extension Blue {
    var appDelegate:AppDelegate {
        return UIApplication.sharedApplication().delegate as! AppDelegate
    }
}

extension Green {
    var appDelegate:AppDelegate {
        return UIApplication.sharedApplication().delegate as! AppDelegate
    }
}
...

Answer 1

You just want to make your app delegate available, which is sensible in most contexts. I recommend the convenience of a global variable (write this above your app delegate class):

let SharedAppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

Answer 2

You should use @Mundi 's answer if you can, but here is version if you would want to allow AppDelegate to limited number of structures.

You can make a protocol and add this variable to everyone conforming to this protocol:

protocol AppDelegatable {
    var appDelegate: AppDelegate { get }
}

extension AppDelegatable {
    var appDelegate: AppDelegate {
        return UIApplication.sharedApplication().delegate as! AppDelegate
    }
}

Answer 3

You could always do:

extension NSObject
{
    var appDelegate:AppDelegate {
        return UIApplication.sharedApplication().delegate as! AppDelegate
    }
}

if you need any kind of extension to be carried out to most of your objects