Do Swift screensavers work in Mac OS X before Yosemite?

I rewrote the screen saver template that Xcode generates from Objective-C into Swift and when I try to load it I get this message:

You cannot use the BlahBlah screensaver with this version of MacOSX.

Please contact the vendor to get a new version of the screen saver.

I'm currently running Mavericks. Does it mean that Swift screen savers only work in Yosemite, or not even there?

This is the Swift code I used to replace the Objetive-C one:

import Foundation
import ScreenSaver

class BlahBlahView : ScreenSaverView {
    convenience override init() {
        self.init(frame: CGRectZero, isPreview: false)
    }

    override init(frame: NSRect, isPreview: Bool) {
        super.init(frame: frame, isPreview: isPreview)

        setAnimationTimeInterval(1.0 / 30.0)
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }


    override func startAnimation() {
        super.startAnimation()
    }

    override func stopAnimation() {
        super.stopAnimation()
    }

    override func drawRect(rect: NSRect) {
        super.drawRect(rect)
    }

    override func animateOneFrame() {

    }

    override func hasConfigureSheet() -> Bool {
        return false
    }

    override func configureSheet() -> NSWindow? {
        return nil
    }
}

These are my project settings:

This was originally an Objective-C project (there's no Swift Screensaver template) created on MacOSX 10.9 and the APIs I'm using, Screensaver, have existed for years.