Question

I'm a swift newbie. Any help is appreciated.

I have a stack of 10 images. I want the user to be able to swipe up and down to update the the image view to new images.

For example: the Image View starts of by displaying 1.jpg. Then the user gestures down on the Image View and it updates the image to 2.jpg then 3.jpg... etc. depending on how far the gesture is held (kind of like an animation). I am able to update the image by one increment using the following code:

@IBAction func down(sender: UISwipeGestureRecognizer) {

        image.image = UIImage(named: "2.jpg")

    }

How can I make this a continuous gesture?

The end result should look something like this: https://figure1.com/sections/blog/wp-content/uploads/2014/08/resized.gif

Answer 1

So let's start off first things first.

Based off the idea that this is distance dragged

1) We need a UIScrollView()

2) Set the Scrollview Frame to the frame of the screen

3) Allow use of scrollview delegate, so add UIScrollViewDelegate to the list of subclasses (At the top where it says ClassName: list, of, subclasses, here, separated, by, commas)

4) In your class (If you are in your View Controller class), add the delegate to the scrollview

5) Let's set the contentSize of the scrollView

6) Let's add the images to your view, using a loop

7) Before step 6, make sure that your images are named something with numbers, and the same name, such as Image1 Image2 Image3 so that we can loop through them.

8) Declare a UIImage array

9) I was gonna keep typing steps but here you go :P

class ViewController:UIViewController, UIScrollViewDelegate {

    let scrollView = UIScrollView()
    let images:[UIImage] = []
    let imageView:UIImageView!

    override func viewDidLoad() {

        //Setting up stuff
        for index in 0 ..< 10 {
            //It's either %t, %i or %d (I don't recall which is which lol)
            images.append(UIImage(named: String(format: "Image %i", index)))
        }            

        imageView = UIImageView(frame: view.bounds)
        imageView.contentMode = .ScaleAspectFit
        imageView.image = images[0]
        imageView.backgroundColor = UIColor.clearColor()
        self.view.addSubview(imageView)

        scrollView.frame = view.bounds
        scrollView.delegate = self
        scrollView.backGroundColor = UIColor.clearColor()

        //Let's say every time the user drags to 1/10 of the screen, the picture will change
        scrollView.contentSize = CGSize(width: self.view.frame.width, height: self.view.frame.height+(self.view.frame*(1/10)*CGFloat(images.count)))
        self.view.addSubview(scrollView)
    }

    //Now let's add some UIScrollView delegates to be called whenever the user scrolls!

    func scrollViewDidScroll(scrollView: UIScrollView) {
        if(scrollView.contentOffSet.y > self.view.frame.height) {
            //(1/10) because we are changing the scrollView every 1/10 of the screen
            let pictureCount = scrollView.contentOffset.y/scrollView.frame.height*(1/10)
            imageView.image = images[pictureCount]
        }
    }
}

Don't quote me off this, mainly because I pulled it out of the air, so if it has errors/bugs, I apologize, but feel free to comment and I will try to adjust what is needed.

Creating swipe gesture in swift to scroll through image stack

1 个答案: