Property overloading

Hi Everyone,
I am trying to reduce boilerplate code when writing custom UIViewController subclasses which talk to a custom UIView subclass, like in a traditional MVC design, and I would like to use the following pattern in many places in my apps:

protocol ViewTypeable {
    associatedtype ViewType: UIView
    var view: ViewType { get }
}
extension ViewTypeable where Self: UIViewController {
    var view: ViewType { return self.view as! ViewType }
}

I'm not sure how others would call this, but I call it property overloading, because it's a bit similar to how we can overload a function by changing the type of a parameter.
Here is a simple exemple of how I use it:

class View1: UIView {
    var text1 = ""
}
class ViewController1: UIViewController, ViewTypeable {
    typealias ViewType = View1
    override func loadView() {
        self.view = View1()
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.text1 = "some text"
    }
}

In the above example, when I start typing self.view in XCode, autocompletion shows 2 view properties, one of type UIView and the other of type View1.
I don't really understand what is happening under the hood, so I thought I should ask the good people at swift forums if this technique is considered safe, or if it is likely to break in a future version of Swift, particularly this line:
var view: ViewType { return self.view as! ViewType }

Thanks.

I don't think it will break, but UIViewController.view (most specific) will always have precedence over ViewTypeable.view (less specific) when in a context where you know the type of the controller.
I suggest renaming the property in the protocol and avoid all naming resolution issues :slight_smile:

1 Like
Terms of Service

Privacy Policy

Cookie Policy