Open Radar

 
Summary:
Currently, using any selector-based API requires that the developer know how Swift methods are mapped to Objective-C selectors. Swift should not require developers to know this; instead, it should include a language feature to construct the selector for you.

Steps to Reproduce:

1. Forget everything you know about how Objective-C works.

2. Define a class like this:

    class ButtonHandler: NSObject {
        func buttonPressed(sender: AnyObject?) { println(“Pressed!” }
    }

3. Create a UIButton or NSButton and a ButtonHandler.

4. Attempt to make the ButtonHandler the button’s target in some Swifty way, for instance:

    button.addTarget(handler, action: handler.buttonPressed, forControlEvents: .TouchUpInside)

Expected Results:
This, or something like it, succeeds.

Actual Results:
It does not. You must know that the selector for the buttonPressed method is “buttonPressed:” to make this work.

Notes:
Last week, the first developers started learning to use Cocoa without knowing Objective-C. These people don’t know how selectors work and, if Swift is to be a first-class Cocoa language, shouldn’t have to, at least not beyond knowing that they represent a method name.

The “handler.buttonPressed” above is merely one example of how this feature might be implemented. Other possibilities include:

    handler.buttonPressed.selector
    ButtonHandler.buttonPressed.selector
    Selector(handler.buttonPressed)
    Selector(ButtonHandler.buttonPressed)
    @selector(buttonPressed(sender:))