Blog - Swipe Content with Subtle Transition

Swipe Content with Subtle Transition

import UIKit

class SwipeViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UIScrollViewDelegate {

    @IBOutlet var imageViewBackground: UIImageView!
    @IBOutlet var collectionView: UICollectionView!
    
    let arraySampleContent:[[String: String]] = [
        ["text": "content 1", "image_name": "img_background_1"],
        ["text": "content 2", "image_name": "img_background_2"],
        ["text": "content 3", "image_name": "img_background_3"]
    ]
    
    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

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

    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

    // MARK: - UICollectionViewDataSource
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        
        // number of sample data
        return arraySampleContent.count
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        
        // get content/text
        let content = arraySampleContent[indexPath.row]
        let text = content["text"]
        
        // get cell
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
        
        // get label via tag then set text to label
        let label = cell.viewWithTag(100) as! UILabel
        label.text = text
        
        // return cell
        return cell
    }
    
    
    // MARK: - UICollectionViewDelegate
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize {
        
        // return collectionView's width and size
        return CGSize(width: collectionView.frame.size.width, height: collectionView.frame.size.height)
    }
    
    // MARK: - UIScrollViewDelegate
    
    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        
        // determine the index of the new page
        let pageWidth = collectionView.frame.size.width
        let index:Int = Int(collectionView.contentOffset.x / pageWidth)
        
        // get sample content
        let currentSampleContent = arraySampleContent[index]
        let stringImageName = currentSampleContent["image_name"]!
        let imageTo = UIImage(named: stringImageName)
        
        // transition animation for new background image
        UIView.transition(with: imageViewBackground, duration: 0.8, options: .transitionCrossDissolve, animations: {
            
            // set image to imageView
            self.imageViewBackground.image = imageTo
        }, completion: nil)
    }
}