Swift - Tinder effect

Question

How can I achieve Tinder effect in Swift?

I mean, I have an image and want to accept if I swipe to right and reject if I swipe to left.

I can do it with the code bellow:

@IBAction func SwipeRight(sender: UISwipeGestureRecognizer) {
    UIView.animateWithDuration(1) {
        self.Imagem.center = CGPointMake(self.Imagem.center.x - 150, self.Imagem.center.y )
    }
    //other things after acception
}

and

@IBAction func SwipeLeft(sender: UISwipeGestureRecognizer) {
    UIView.animateWithDuration(1) {
        self.Imagem.center = CGPointMake(self.Imagem.center.x + 150, self.Imagem.center.y )
    }
    //other things after rejection
}

But this way the user can't cancel the action. I want that if the user swipes to a delta distance from the edge (left or right), it would appear an image to let the user now that, if he ends the movement, the action will take place. Otherwise, the user can, without ending the movement, go back to a distance bigger than delta, and the action would be cancelled.

Answer 1

I would like to thanks the people who suggested solutions. Follow the solution I developed with a huge help of a lot of people from Stack Overflow:

@IBAction func Arrastei(sender: UIPanGestureRecognizer) {
    var origem =  CGPoint(x: 0, y: 0)
    var translation : CGPoint = sender.translationInView(Imagem)

    var txy : CGAffineTransform = CGAffineTransformMakeTranslation(translation.x, -abs(translation.x) / 15)
    var rot : CGAffineTransform = CGAffineTransformMakeRotation(-translation.x / 1500)
    var t : CGAffineTransform = CGAffineTransformConcat(rot, txy);
    Imagem.transform = t

    if (translation.x > 100) {
        LbResultado.textColor = btVerdadeiro.textColor
        LbResultado.text = btVerdadeiro.text
        LbResultado.hidden = false
    } else {
        if (translation.x < -100) {
            LbResultado.textColor = btFalso.textColor
            LbResultado.text = btFalso.text
            LbResultado.hidden = false
        } else {
            LbResultado.hidden = true
        }
    }


    if sender.state == UIGestureRecognizerState.Ended {
        if (translation.x > 100) {
            objJogo.Rodada_Vigente!.Responder(true)
        } else {

            if (translation.x < -100) {
                objJogo.Rodada_Vigente!.Responder(false)
            } else {
                sender.view.transform = CGAffineTransformMakeTranslation(origem.x, origem.y)
                sender.view.transform = CGAffineTransformMakeRotation(0)
            }
        }
    }
}

This solution uses:

Imagem --> UIImageView - to be accepted or rejected

LbResultado --> UITextView - to show the user he is in acceptance or rejection area

There is no math calculations to set rotation and translation. I used values that give me a visually good effect.

The action (acceptance and rejection) area is when the user drag image more than 100 pixels to left (reject) or right (accept). If the user ends the movement out the action area, the image will go back to its original position.

I will be glad if someone suggests improvements to this code.