ios - 如何使新 ImageView 可移动？

Question

我一直在尝试拼凑一个项目，该项目包含一个在侧面滚动的 Collection View ，当点击一个单元格时，它将向场景添加一个新的 ImageView 。我希望这张新图片可以拖动。

我的代码当前显示 Collection View ，点击时添加新图像(我称之为贴纸)。

我还没有完全弄清楚如何让它放置正确的贴纸，但我的首要目标是确保出现的东西可以移动。

import UIKit

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
    @IBOutlet weak var collectionView: UICollectionView!

    let stickers: [UIImage] = [
        UIImage(named: "cow")!,
        UIImage(named: "chicken")!,
        UIImage(named: "pig")!,
        UIImage(named: "cow")!,
        UIImage(named: "chicken")!,
        UIImage(named: "pig")!,
        UIImage(named: "cow")!,
        UIImage(named: "chicken")!,
        UIImage(named: "pig")!,
    ]

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return stickers.count
    }

    var activeSticker = UIImage(named: "cow")

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CollectionViewCell
        cell.stickerImage.image = stickers[indexPath.item]
        cell.backgroundColor = UIColor(white: 1, alpha: 0.9)
        cell.translatesAutoresizingMaskIntoConstraints = false
        cell.contentMode = .scaleAspectFill
        cell.clipsToBounds = true
        cell.layer.cornerRadius = 7
        let addSticker = UIButton(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
        addSticker.addTarget(self, action: #selector(addStickerTapped), for: UIControl.Event.touchUpInside)
        activeSticker = cell.stickerImage.image
        cell.addSubview(addSticker)
        return cell
    }    

    @IBAction func addStickerTapped() -> Void {
        print("Hello Sticker Button")
        let image = activeSticker //UIImage(named: imageName)
        let imageView = UIImageView(image: image!)
        imageView.frame = CGRect(x: 100, y: 100, width: 100, height: 200)
        imageView.contentMode = .scaleAspectFit
        imageView.isUserInteractionEnabled = true
        self.view.addSubview(imageView)
        //Imageview on Top of View
        self.view.bringSubviewToFront(imageView)
    }
}

Answer 1

要在 self.view 中移动 imageView，您可以使用 UIPanGestureRecognizer。添加手势识别器，例如，在 viewDidLoad 中:

class ViewController: UIViewController {

    var selectedImageView: UIImageView?

    override func viewDidLoad() {
        super.viewDidLoad()
        addPanGestureRecognizer()
    }

    func addPanGestureRecognizer() {
        let pan = UIPanGestureRecognizer(target: self, action: #selector(moveImageView(_:)))
        // set up and optimize pan gesture options here if you need to
        self.view.addGestureRecognizer(pan)
    }

    @objc func moveImageView(_ sender: UIPanGestureRecognizer) {
        // assign one of your image views to selectedImageView to ensure you only move one image view at a time
        // for example in func addStickerTapped() you could assign selectedImageView = imageView

        guard let selectedImageView = selectedImageView else {
            return
        }

        switch sender.state {
        case .changed, .ended:
            selectedImageView.center = selectedImageView.center.offset(by: sender.translation(in: self.view))
            sender.setTranslation(.zero, in: self.view)
        default:
            break
        }
    }
}

extension CGPoint {
    func offset(by point: CGPoint) -> CGPoint {
        return CGPoint(x: self.x + point.x, y: self.y + point.y)
    }
}