Swift implementation of https://github.com/cwRichardKim/TinderSimpleSwipeCards . Note: Code still requires a lot of improvements, especially Object Oriented Design changes. (Started out with iOS a few weeks backs, so still learning :) (It wont work with the new release of Xcode / Swift beta 2.0 (Still a WIP))

DraggableView.swift

//
//  DraggableView.swift
//  Swipe
//
//  Created by Shayon Mukherjee on 11/5/14.
//  Copyright (c) 2014 Swipe. All rights reserved.
//
import Foundation
import UIKit

let ACTION_MARGIN = 120 //%%% distance from center where the action applies. Higher = swipe further in order for the action to be called
let SCALE_STRENGTH = 4 //%%% how quickly the card shrinks. Higher = slower shrinking
let SCALE_MAX : CGFloat = 0.93 //%%% upper bar for how much the card shrinks. Higher = shrinks less
let ROTATION_MAX = 1 //%%% the maximum rotation allowed in radians.  Higher = card can keep rotating longer
let ROTATION_STRENGTH = 320 //%%% strength of rotation. Higher = weaker rotation
let ROTATION_ANGLE = M_PI/8 //%%% Higher = stronger rotation angle

class DraggableView : UIView {
    var xFromCenter : CGFloat
    var yFromCenter : CGFloat
    var panGestureRecognizer : UIPanGestureRecognizer
    var originalPoint : CGPoint
    var overlayView : OverlayView
    var information : UILabel

    required init(coder aDecoder: NSCoder) {
        xFromCenter = 0.0
        yFromCenter = 0.0
        panGestureRecognizer = UIPanGestureRecognizer()
        originalPoint = CGPoint()
        overlayView = OverlayView(coder: aDecoder)
        information = UILabel()
        super.init(coder: aDecoder)
    }

    override init(frame: CGRect) {
        xFromCenter = 0.0
        yFromCenter = 0.0
        panGestureRecognizer = UIPanGestureRecognizer()
        originalPoint = CGPoint()
        overlayView = OverlayView(coder: NSCoder())
        information = UILabel()

        super.init(frame: frame)

        information = UILabel(frame: CGRectMake(0, 50, self.frame.size.width, 100))
        information.text = "no info given"
        information.textAlignment = NSTextAlignment.Center
        information.textColor = UIColor.blackColor()

        self.backgroundColor = UIColor(red:72/255, green:145/255,blue:206/255,alpha:1)


        panGestureRecognizer = UIPanGestureRecognizer(target: self, action: "beingDragged:")

        self.addGestureRecognizer(panGestureRecognizer)
        self.addSubview(information)

        overlayView = OverlayView(frame: CGRectMake(self.frame.size.width/2-100, 0, 100, 100))
        overlayView.alpha = 0
        self.addSubview(overlayView)

        self.superview
    }

    func setupView() {
        self.layer.cornerRadius = 4
        self.layer.shadowRadius = 3
        self.layer.shadowOpacity = 0.2
        self.layer.shadowOffset = CGSizeMake(1, 1)
    }

    //%%% called when you move your finger across the screen.
    // called many times a second
    func beingDragged(gestureRecognizer: UIPanGestureRecognizer){
        //%%% this extracts the coordinate data from your swipe movement. (i.e. How much did you move?)

        //%%% positive for right swipe, negative for left
        xFromCenter = gestureRecognizer.translationInView(self).x
        //%%% positive for up, negative for down
        yFromCenter = gestureRecognizer.translationInView(self).y

        //%%% checks what state the gesture is in. (are you just starting, letting go, or in the middle of a swipe?)
        switch (gestureRecognizer.state) {
            //%%% just started swiping

        case UIGestureRecognizerState.Began:
            self.originalPoint = self.center
            break


            //%%% in the middle of a swipe
        case UIGestureRecognizerState.Changed:
            //%%% dictates rotation (see ROTATION_MAX and ROTATION_STRENGTH for details)
            var rotationStrength = min(CGFloat(xFromCenter) / CGFloat(ROTATION_STRENGTH), CGFloat(ROTATION_MAX)) as CGFloat

            //%%% degree change in radians
            var rotationAngel : CGFloat = (CGFloat(ROTATION_ANGLE) * rotationStrength)

            //%%% amount the height changes when you move the card up to a certain point
            var scale = max((CGFloat(1) - CGFloat(rotationStrength) / CGFloat(SCALE_STRENGTH)), SCALE_MAX) as CGFloat

            //%%% move the object's center by center + gesture coordinate
            self.center = CGPointMake(self.originalPoint.x + xFromCenter, self.originalPoint.y + yFromCenter)

            //%%% rotate by certain amount
            var transform : CGAffineTransform = CGAffineTransformMakeRotation(rotationAngel)

            //%%% scale by certain amount
            var scaleTransform : CGAffineTransform = CGAffineTransformScale(transform, scale, scale)

            //%%% apply transformations
            self.transform = scaleTransform
            self.updateOverlay(xFromCenter)

            break

        //%%% let go of the card
        case UIGestureRecognizerState.Ended:
            self.afterSwipeAction()
            break;

        case UIGestureRecognizerState.Possible:break;
        case UIGestureRecognizerState.Cancelled:break;
        case UIGestureRecognizerState.Failed:break;
        }

    }
    //%%% checks to see if you are moving right or left and applies the correct overlay image
    func updateOverlay(distance: CGFloat){

        if (distance > 0) {
            overlayView.mode = GGOverlayViewMode.GGOverlayViewModeRight;
        } else {
            overlayView.mode = GGOverlayViewMode.GGOverlayViewModeLeft;
        }

        overlayView.alpha = min(CGFloat(distance)/100, 0.4);
    }
    //%%% called when the card is let go
    func afterSwipeAction() {
        if(xFromCenter > CGFloat(ACTION_MARGIN))
        {
            self.rightAction()
        }
        else if(xFromCenter < CGFloat(-ACTION_MARGIN))
        {
            self.leftAction()
        }
        else
        {
            UIView.animateWithDuration(0.3, animations: { () -> Void in
                self.center = self.originalPoint
                self.transform = CGAffineTransformMakeRotation(0)
                self.overlayView.alpha = 0
            })
        }
    }

    func rightAction() {
        var finishPoint : CGPoint = CGPointMake(500, 2*yFromCenter + self.originalPoint.y)

        UIView.animateWithDuration(0.3, animations: { () -> Void in
            self.center = finishPoint
        }) { (complete) -> Void in
            self.removeFromSuperview()
        }

        println("YES")

    }

    func leftAction() {
        var finishPoint : CGPoint = CGPointMake(-500, 2*yFromCenter + self.originalPoint.y)

        UIView.animateWithDuration(0.3, animations: { () -> Void in
            self.center = finishPoint
            }) { (complete) -> Void in
                self.removeFromSuperview()
        }

        println("NO")

    }

    func rightClickAction() {
        var finishPoint : CGPoint = CGPointMake(600, self.center.y)

        UIView.animateWithDuration(0.3, animations: { () -> Void in
            self.center = finishPoint
            self.transform = CGAffineTransformMakeRotation(1)
            }) { (complete) -> Void in
                self.removeFromSuperview()
        }

        println("YES")

    }

    func leftClickAction() {
        var finishPoint : CGPoint = CGPointMake(-600, self.center.y)

        UIView.animateWithDuration(0.3, animations: { () -> Void in
            self.center = finishPoint
            self.transform = CGAffineTransformMakeRotation(-1)
            }) { (complete) -> Void in
                self.removeFromSuperview()
        }

        println("No")

    }


}

DraggableViewBackground.swift

//
//  DraggableViewBackground.swift
//  Swipe
//
//  Created by Shayon Mukherjee on 11/5/14.
//  Copyright (c) 2014 Swipe. All rights reserved.
//

import Foundation
import UIKit

class DraggableViewBackground : UIView {

    required init(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    //this makes it so only two cards are loaded at a time to
    //avoid performance and memory costs

    let MAX_BUFFER_SIZE = 5 //%%% max number of cards loaded at any given time, must be greater than 1
    let CARD_HEIGHT : CGFloat = 386  //%%% height of the draggable card
    let CARD_WIDTH : CGFloat = 290 //%%% width of the draggable card

    var cardsLoadedIndex : Int = 0 //%%% the index of the card you have loaded into the loadedCards array last
    var loadedCards = [DraggableView]() //%%% the array of card loaded (change max_buffer_size to increase or decrease the number of cards this holds)

    var menuButton : UIButton
    var messageButton : UIButton
    var checkButton : UIButton
    var xButton : UIButton

    var exampleCardLabels : AnyObject = [] //%%% all the labels I'm using as example data at the moment
    var allCards = [DraggableView]() //%%% all the cards

    override init(frame: CGRect) {
        menuButton = UIButton()
        messageButton = UIButton()
        checkButton = UIButton()
        xButton = UIButton()
        super.init(frame: frame)
        self.setupView()
        exampleCardLabels = ["first", "second", "third", "fourth", "fifth"] //%%% placeholder for card-specific information
        cardsLoadedIndex = 0;
        self.loadCards()
    }

//  Frontend UI styling happening here
    func setupView() {
        // Styling background
        self.backgroundColor = UIColor.whiteColor()

        //  Styling menuButton
        menuButton = UIButton(frame: CGRectMake(17, 34, 22, 15))
        menuButton.setImage(UIImage(named: "menuButton"), forState: UIControlState.Normal)

        //  Styling messageButton
        messageButton = UIButton(frame: CGRectMake(284, 34, 18, 18))
        messageButton.setImage(UIImage(named: "messageButton"), forState: UIControlState.Normal)

        //  Styling xButton
        xButton = UIButton(frame: CGRectMake(60, 485, 59, 59))
        xButton.setImage(UIImage(named: "xButton"), forState: UIControlState.Normal)

        //  Add target for checkButton (Swipe Left)
        xButton.addTarget(self, action: "swipeLeft", forControlEvents: UIControlEvents.TouchUpInside)

        //  Styling checkButton
        checkButton = UIButton(frame: CGRectMake(200, 485, 59, 59))
        checkButton.setImage(UIImage(named: "checkButton"), forState: UIControlState.Normal)

        //  Add target for checkButton (Swipe Right)
        checkButton.addTarget(self, action: "swipeRight", forControlEvents: UIControlEvents.TouchUpInside)

        // Add subviews
        self.addSubview(menuButton)
        self.addSubview(messageButton)
        self.addSubview(xButton)
        self.addSubview(checkButton)
    }

    func loadCards() {
        if(exampleCardLabels.count > 0){
            //%%% if the buffer size is greater than the data size, there will be an array error, so this makes sure that doesn't happen
            var numLoadedCardsCap = exampleCardLabels.count > MAX_BUFFER_SIZE ? MAX_BUFFER_SIZE : exampleCardLabels.count

            //%%% loops through the exampleCardsLabels array to create a card for each label.  This should be customized by removing "exampleCardLabels" with your own array of data
            for (var i = 0; i < exampleCardLabels.count; i++) {
                var newCard : DraggableView = self.createDraggableViewWithDataAtIndex(i)
                allCards.append(newCard)

                if(i < numLoadedCardsCap) {
                    //%%% adds a small number of cards to be loaded
                    loadedCards.append(newCard)
                }
            }
        }

        //%%% displays the small number of loaded cards dictated by MAX_BUFFER_SIZE so that not all the cards
        // are showing at once and clogging a ton of data
        for (var i = 0; i < loadedCards.count; i++) {
            if (i > 0) {
                self.insertSubview(loadedCards[i] as UIView, belowSubview: loadedCards[i-1] as UIView)
            } else {
                self.addSubview(loadedCards[i] as UIView)
            }
            cardsLoadedIndex++; //%%% we loaded a card into loaded cards, so we have to increment
        }
    }

    //%%% action called when the card goes to the left.
    // This should be customized with your own action

    func cardSwipedLeft(card: UIView) {
        //do whatever you want with the card that was swiped
        //    DraggableView *c = (DraggableView *)card;
        loadedCards.removeAtIndex(0)  //%%% card was swiped, so it's no longer a "loaded card"

        //%%% if we haven't reached the end of all cards, put another into the loaded cards
        if(cardsLoadedIndex < allCards.count) {
            loadedCards.append(allCards[cardsLoadedIndex])

            //%%% loaded a card, so have to increment count
            cardsLoadedIndex++

            self.insertSubview(loadedCards[MAX_BUFFER_SIZE-1] as UIView, belowSubview: loadedCards[MAX_BUFFER_SIZE-2] as UIView)

        }
    }

    //%%% action called when the card goes to the left.
    // This should be customized with your own action
    func cardSwipedRight(card: UIView) {
        //do whatever you want with the card that was swiped
        //    DraggableView *c = (DraggableView *)card;

        loadedCards.removeAtIndex(0)  //%%% card was swiped, so it's no longer a "loaded card"

        //%%% if we haven't reached the end of all cards, put another into the loaded cards
        if(cardsLoadedIndex < allCards.count) {
            loadedCards.append(allCards[cardsLoadedIndex])

            //%%% loaded a card, so have to increment count
            cardsLoadedIndex++
            self.insertSubview(loadedCards[MAX_BUFFER_SIZE-1] as UIView, belowSubview: loadedCards[MAX_BUFFER_SIZE-2] as UIView)
        }
    }

    //%%% when you hit the right button, this is called and substitutes the swipe
    func swipeRight() {
        var dragView : DraggableView = loadedCards.first!
        dragView.overlayView.mode = GGOverlayViewMode.GGOverlayViewModeRight
        UIView.animateWithDuration(0.2, animations: { () -> Void in
            dragView.overlayView.alpha = 1
        })
//        dragView.rightClickAction
    }

    func swipeLeft() {
        var dragView : DraggableView = loadedCards.first!
        dragView.overlayView.mode = GGOverlayViewMode.GGOverlayViewModeLeft
        UIView.animateWithDuration(0.2, animations: { () -> Void in
            dragView.overlayView.alpha = 1
        })
//        dragView.leftClickAction
    }

    //%%% creates a card and returns it.  This should be customized to fit your needs.
    // use "index" to indicate where the information should be pulled.  If this doesn't apply to you, feel free
    // to get rid of it (eg: if you are building cards from data from the internet)

    func createDraggableViewWithDataAtIndex(index: Int) -> DraggableView{
        var draggableView : DraggableView = DraggableView(frame: CGRectMake((self.frame.size.width - CARD_WIDTH)/2, (self.frame.size.height - CARD_HEIGHT)/2, CARD_WIDTH, CARD_HEIGHT))
        //%%% placeholder for card-specific information
        draggableView.information.text = exampleCardLabels.objectAtIndex(index) as? String
        return draggableView
    }
}

OverlayView.swift

//
//  OverlayView.swift
//  Swipe
//
//  Created by Shayon Mukherjee on 11/5/14.
//  Copyright (c) 2014 Swipe. All rights reserved.
//

import Foundation
import UIKit

enum GGOverlayViewMode : Int {
    case GGOverlayViewModeLeft
    case GGOverlayViewModeRight
}

class OverlayView : UIView {
    var mode : GGOverlayViewMode
    var imageView : UIImageView


    override init(frame: CGRect) {
        mode = GGOverlayViewMode.GGOverlayViewModeRight // tmp init
        imageView = UIImageView()
        super.init(frame: frame)

        self.backgroundColor = UIColor.whiteColor()
        imageView = UIImageView(image: UIImage(named: "noButton"))
        self.addSubview(imageView)
    }

    required init(coder aDecoder: (NSCoder!)) {
        mode = GGOverlayViewMode.GGOverlayViewModeRight // tmp init
        imageView = UIImageView()
        super.init()
    }

    func setMode(mode: GGOverlayViewMode){
//        if (_ mode == mode) {
//            return
//        }
//
//        _mode = mode;

        if(mode == GGOverlayViewMode.GGOverlayViewModeLeft) {
            imageView.image = UIImage(named: "noButton")
        } else {
            imageView.image = UIImage(named: "yesButton")
        }
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        imageView.frame = CGRectMake(50, 50, 100, 100)
        imageView.backgroundColor = UIColor(red:72/255, green:145/255,blue:206/255,alpha:1)
    }
}

ViewController.swift

//
//  TimelineViewController.swift
//  Swipe
//
//  Created by Shayon Mukherjee on 11/4/14.
//  Copyright (c) 2014 Swipe. All rights reserved.
//

import Foundation
import UIKit

class ViewController : UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        var draggableBackground = DraggableViewBackground(frame: self.view.frame)
        self.view.addSubview(draggableBackground)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}