TinderSimpleSwipeCards - https://github.com/cwRichardKim/TinderSimpleSwipeCards/issues/12

CardView.h

#import <UIKit/UIKit.h>


@protocol CardDelegate;

typedef NS_ENUM(NSUInteger, kCardState) {
    kCardStateIdle = 0,
    kCardStateMoving = 1,
    kCardStateGone = 2
};

// The Position of the Card
typedef NS_ENUM(NSInteger, kCardPosition) {
    kCardPositionTop = 0,
    kCardPositionBack = 1
};

/*!
 *    Implements the Views inside the Cards
 */
@interface CardView : UIView

#pragma mark - Properties

/*!
 *    Defines the current state of the card
 */
@property (nonatomic) kCardState state;

/*!
 *    The Weight of the Card indicates its position in the stack
 */
@property (nonatomic) kCardPosition position;

/*!
 * The delegate that will listen to the notifications
 * on created on pan gesture recognizers
 */
@property (nonatomic, weak) id <CardDelegate> delegate;

/*!
 *    Where in the array is located the  view
 */
@property (nonatomic) NSInteger index;

#pragma mark - Methods

#pragma mark Init

/*!
 * Designated Initializer
 *
 * This method inits the view
 * and set the  to fetch
 * also renders the view with 's data
 *
 * @param CGRect frame for view's bounds
 * @param ViewDelegate delegate to send events
 * @param  *  to render the view info
 */
- (void) setFrame:(CGRect)frame delegate:(id<CardDelegate>) delegate;

#pragma mark Instance

/*!
 * Swipes the view to the left
 * programatically
 */
- (void) swipeLeft;

/*!
 * Swipes the view to the right
 * programatically
 */
- (void) swipeRight;

/*!
 * Swipes the view up
 * programatically
 */
- (void) swipeUp;

/*!
 * Swipes the view down
 * programatically
 */
- (void) swipeDown;

/*!
 *    Cancels a Swipe
 */
- (void) cancelSwipe;

@end


@protocol CardDelegate <NSObject>

#pragma mark - Delegate Methods

/*!
 * Method called when the view will begin pan gesture
 * @param Card * Card
 */
- (void) willBeginSwipeInCard : (CardView *) card;

/*!
 * Method called when the view did end pan gesture
 * @param Card * Card
 */
- (void) didEndSwipeInCard : (CardView *) card;

/*!
 * Method called when the view did not reach a detected position
 * @param Card * Card
 */
- (void) didCancelSwipeInCard : (CardView *) card;

/*!
 * Method called when the view was swiped left
 * @param Card * Card
 */
- (void) swipedLeftInCard : (CardView *) card;

/*!
 * Method called when the view was swiped right
 * @param Card * Card
 */
- (void) swipedRightInCard : (CardView *) card;

/*!
 * Method called when the view was swiped up
 * @param Card * Card
 */
- (void) swipedUpInCard : (CardView *) card;

/*!
 * Method called when the view was swiped down
 * @param Card * Card
 */
- (void) swipedDownInCard : (CardView *) card;

/*!
 * Method called when the view button was pressed
 * @param Card * Card;
 */
- (void) wasTouchedDownInCard : (CardView *) card;

/*!
 *    Method called when the state was changed
 *
 *    @param  Card * Card;
 */
- (void) didChangeStateInCard: (CardView *) card;

/*!
 *    Ask the delegate if the card should move
 *
 *    @param Card the card
 *
 *    @return YES if the card should move
 */
- (BOOL) shouldMoveCard: (CardView *) card;

@end

CardView.m

#import "CardView.h"

// Constants Declaration

// This constant represent the distance from the center
// where the action applies. A higher value means that
// the user needs to draw the view further in order for
// the action to be executed.

#define ACTION_MARGIN 120

// This constant is the distance from the center. But vertically

#define Y_ACTION_MARGIN 100


// This constant represent how quickly the view shrinks.
// The view will shrink when is beign moved out the visible
// area.
// A Higher value means slower shrinking

#define SCALE_QUICKNESS 4

// This constant represent how much the view shrinks.
// A Higher value means less shrinking

#define SCALE_MAX .93

// This constant represent the rotation angle

#define ROTATION_ANGLE M_PI / 8

// This constant represent the maximum rotation angle
// allowed in radiands.
// A higher value enables more rotation for the view

#define ROTATION_MAX 1

// This constant defines how fast
// the rotation should be.
// A higher values means a faster rotation.

#define ROTATION_QUICKNESS 320

@interface CardView()

// Internal Variables
@property (nonatomic) CGFloat xFromCenter;

@property (nonatomic) CGFloat yFromCenter;

@property (nonatomic) CGPoint originalPoint;

@end

@implementation CardView

@synthesize state = _state;

- (kCardState) state {
    if (!_state) {
        _state = kCardStateIdle;
    }

    return _state;
}

- (void) setState:(kCardState) state {

    if (_state != state) {
        _state = state;
        [self.delegate didChangeStateInCard:self];
    }
}

- (kCardPosition) position {
    if (!_position) {
        _position = kCardPositionTop;
    }

    return _position;
}

#pragma mark - Init

/*!
 * Designated Initializer
 *
 * This method inits the view
 * and set the feed to fetch
 * also renders the view with feed's data
 *
 * @param CGRect frame for view's bounds
 * @param CardDelegate delegate to send events
 */

- (void) setFrame:(CGRect)frame delegate:(id<CardDelegate>) delegate {

    self.frame = frame;

    self.delegate = delegate;

    [self setupView];
    [self registerSwipeGestures];
}

#pragma mark Init Helper Methods

/*!
 * Round corners of the view
 * and draw a shadow
 * Do another view related
 * actions required on init
 */
- (void) setupView {

    // Draw Shadow
    // And round the view
    self.layer.cornerRadius = 10;
    self.layer.shadowRadius = 3;
    self.layer.shadowOpacity = 0.2;
    self.layer.shadowOffset = CGSizeMake(1,1);

}

/*!
 * Register Pan Gesture
 * and delegates
 */
- (void) registerSwipeGestures {

    UIPanGestureRecognizer * panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePanGesture:)];

    [self addGestureRecognizer:panRecognizer];

}


#pragma mark Pan Gesture Recognizer Handlers

/*!
 * This is the main method for motion detection
 * its called several times a second when the
 * fingers are moved across the screen.
 */
- (void) handlePanGesture: (UIPanGestureRecognizer *) panRecognizer {

    // This extracts the coordinate data from the swipe movement.
    // how much did fingers move.

    // We need to know the X position.
    // A positive value means movement to the right.
    // A negative value means movement to the left.

    self.xFromCenter = [panRecognizer translationInView:self].x;

    // We need to know the Y position.
    // A positive value means up movement.
    // A negative value means down movement.

    self.yFromCenter = [panRecognizer translationInView:self].y;

    // Now we check on wich state our swipe is
    // if is its starting, in the middle or ended
    // the swiping.

    switch (panRecognizer.state) {

            // Swiping just started
        case UIGestureRecognizerStateBegan: {

            // We will save the original point
            // when we started
            self.originalPoint = self.center;

            if (self.delegate) {

                if ([self.delegate shouldMoveCard:self]) {

                    // And tell the delegate
                    // that the movement just started
                    [self.delegate willBeginSwipeInCard:self];

                }

            }


            break;
        }

            // Swiping is in course
        case UIGestureRecognizerStateChanged: {

            // Animate the view

            if (self.delegate) {

                // If delegate is present
                // ask if it should move the card
                if ([self.delegate shouldMoveCard:self]) {

                    [self animateView];
                }

            } else {
                [self animateView];
            }

            break;
        }

        // Swiping ended
        case UIGestureRecognizerStateEnded: {

            if (self.delegate) {

                if ([self.delegate shouldMoveCard:self]) {

                    [self detectSwipeDirection];
                }

            } else {
                [self detectSwipeDirection];
            }

            break;
        }

        default:
            break;
    }
}


#pragma mark Helper Methods

/*!
 * Rotates the view
 * and changes its scale and position
 */
- (void) animateView {

    // Do some black magic math
    // for rotating and scale

    // Gets the rotation quickness
    // see constants.

    CGFloat rotationQuickness = MIN(self.xFromCenter / ROTATION_QUICKNESS, ROTATION_MAX);

    // Change the rotation in radians
    CGFloat rotationAngle = (CGFloat) (ROTATION_ANGLE * rotationQuickness);

    // the height will change when the view reaches certain point
    CGFloat scale = MAX(1 - fabsf(rotationQuickness) / SCALE_QUICKNESS, SCALE_MAX);

    // move the object center depending on the coordinate
    self.center = CGPointMake(self.originalPoint.x + self.xFromCenter,
                                   self.originalPoint.y + self.yFromCenter);


    // rotate by the angle
    CGAffineTransform rotateTransform = CGAffineTransformMakeRotation(rotationAngle);

    // scale depending on the rotation
    CGAffineTransform scaleTransform = CGAffineTransformScale(rotateTransform, scale, scale);

    // apply transformations
    self.transform = scaleTransform;

    // Change state
    [self changeStateToMoving];
}

/*!
 * With all the values fetched
 * from the pan gesture
 * gets the direction of the swipe
 * when the swipe is done
 */
- (void) detectSwipeDirection {

    if (self.xFromCenter > ACTION_MARGIN) {

        [self performRightAnimation];

    } else if (self.xFromCenter < - ACTION_MARGIN) {

        [self performLeftAnimation];

    } else if(self.yFromCenter < - Y_ACTION_MARGIN) {

        [self performUpAnimation];

    } else if(self.yFromCenter >  Y_ACTION_MARGIN) {

        [self performDownAnimation];

    } else {

        [self performCenterAnimation];

    }

    // And tell the delegate
    // that the swipe just finished
    [self.delegate didEndSwipeInCard:self];
}

- (void) changeStateToIdle {

    // Idle state indicates that the card
    // is showing in the view, but not moving.
    self.state = kJMPTFeedCardStateIdle;
}

- (void) changeStateToGone {

    // Gone state indicates that the card
    // was removed from the view
    self.state = kJMPTFeedCardStateGone;
}

- (void) changeStateToMoving {

    self.state = kJMPTFeedCardStateMoving;

    // Cancel Swipe if Moving but not should
    if (self.delegate && ![self.delegate shouldMoveCard:self]) {
        [self performCenterAnimation];
    }
}

#pragma mark Animation Methods

/*!
 * The view will go to the right
 */
- (void) performRightAnimation {

    CGPoint finishPoint = CGPointMake(500, 2 * self.yFromCenter + self.originalPoint.y);

    [UIView animateWithDuration:0.3  delay:0 options:UIViewAnimationOptionBeginFromCurrentState animations:^{

        self.center = finishPoint;

    } completion:^(BOOL finished) {

        [self removeFromSuperview];

        [self changeStateToGone];

        [self.delegate swipedRightInCard:self];
    }];

}

/*!
 * The view will got to the left
 */
- (void) performLeftAnimation {

    CGPoint finishPoint = CGPointMake(-500, 2 * self.yFromCenter + self.originalPoint.y);

    [UIView animateWithDuration:0.3  delay:0 options:UIViewAnimationOptionBeginFromCurrentState animations:^{

        self.center = finishPoint;

    } completion:^(BOOL finished) {

        [self removeFromSuperview];

        [self changeStateToGone];

        [self.delegate swipedLeftInCard:self];
    }];

}

/*!
 * The view will go up
 * do not remove from view
 * just perfom some goofy moves
 */
- (void) performUpAnimation {

    [UIView animateWithDuration:0.7
                          delay:0
         usingSpringWithDamping:0.56
          initialSpringVelocity:0.0
                        options:UIViewAnimationOptionBeginFromCurrentState
                     animations:^{

                         self.center = self.originalPoint;

                         self.transform = CGAffineTransformMakeRotation(0);

                     } completion:^(BOOL finished) {
                         [self changeStateToIdle];

                         [self.delegate swipedUpInCard:self];
                     }];
}

/*!
 * The view will go down
 * do not remove from view
 * just perfom some goofy moves
 */
- (void) performDownAnimation {

    [UIView animateWithDuration:0.7
                          delay:0
         usingSpringWithDamping:0.56
          initialSpringVelocity:0.0
                        options:UIViewAnimationOptionBeginFromCurrentState
                     animations:^{

                         self.center = self.originalPoint;

                         self.transform = CGAffineTransformMakeRotation(0);

                     } completion:^(BOOL finished) {
                         [self changeStateToIdle];
                         [self.delegate swipedDownInCard:self];
                     }];

}

/*!
 * The view will go to the center
 * (cancel swipe) and reset the values
 */
- (void) performCenterAnimation {

    [UIView animateWithDuration:0.7
                          delay:0
         usingSpringWithDamping:0.56
          initialSpringVelocity:0.0
                        options:UIViewAnimationOptionBeginFromCurrentState
                     animations:^{

                         self.center = self.originalPoint;

                         self.transform = CGAffineTransformMakeRotation(0);

                     } completion:^(BOOL finished) {

                         [self changeStateToIdle];
                         [self.delegate didCancelSwipeInCard:self];
                     }];
}

#pragma mark - Programatically Swipe Methods

- (void) swipeLeft {

    // The same animation but with a delay
    CGPoint finishPoint = CGPointMake(-500, 2 * self.yFromCenter + self.originalPoint.y);

    [self changeStateToMoving];

    [UIView animateWithDuration:0.3  delay:0.3 options:UIViewAnimationOptionBeginFromCurrentState animations:^{

        self.center = finishPoint;

    } completion:^(BOOL finished) {

        if (finished) {
            [self removeFromSuperview];
            [self changeStateToGone];
            [self.delegate swipedLeftInCard:self];
        }

    }];
}

- (void) swipeRight {

    // The same animation, but with a delay
    CGPoint finishPoint = CGPointMake(500, 2 * self.yFromCenter + self.originalPoint.y);

    [self changeStateToMoving];

    [UIView animateWithDuration:0.3  delay:0.3 options:UIViewAnimationOptionBeginFromCurrentState animations:^{

        self.center = finishPoint;

    } completion:^(BOOL finished) {

        if (finished) {
            [self removeFromSuperview];
            [self changeStateToGone];
            [self.delegate swipedRightInCard:self];
        }
    }];
}

- (void) swipeUp {
    //TODO: Implement this
}

- (void) swipeDown {
    //TODO: Implement this
}


- (void) cancelSwipe {
    [self performCenterAnimation];
}

#pragma mark - IBActions

- (IBAction) cardButton: (id)sender {
    [self.delegate wasTouchedDownInCard:self];
}

@end

• https://github.com/cwRichardKim/TinderSimpleSwipeCards
• cwRichardKim/RKSwipeCards#12