如何拖动 UIView 元素并更改位置？

Question

我正在开发一个允许用户创建表单的 iOS 应用程序。表单有许多 UIView 元素存储在堆栈中的 UIScrollView 中。就编辑而言，UIViews 应该改变顺序。

我如何实现这一目标？我想拖动任何 UIView 组件并将其移动到表单中的任何位置。例如。持有第三个元素将激活自身移动。将它移动到第二个元素上将替换它的位置。我正在使用平移手势来移动 UIView。现在我怎么知道点击的视图是否到达了任何 UIView 的顶部？

Answer 1

据我了解您的要求，您希望用户能够移动/重新定位某些 UIView，例如在父视图中拖放。

我建议您使用启用了交互式移动的collectionView。如果你想使用一些库，那么你可以试试https://github.com/ra1028/RAReorderableLayout

或者对于UIView 拖放实现，您可以检查这个 https://blog.apoorvmote.com/uipangesturerecognizer-to-make-draggable-uiview-in-ios-swift/

Answer 2

UICollectionViewController 有几个简单的选项可以通过 canMoveItemAt 委托方法轻松处理 如果您有视图控制器，您可以尝试以下方式：

import UIKit

class LoveProfileEditViewViewController: BaseViewController {
    fileprivate var longPressGesture:UILongPressGestureRecognizer!
    @IBOutlet var theCollectionView:UICollectionView!
    public var items:[String]!

    override func viewDidLoad() {
        super.viewDidLoad()
        let horizontalLayout = UICollectionViewFlowLayout()
        horizontalLayout.scrollDirection = .horizontal
        self.theCollectionView.collectionViewLayout = horizontalLayout
        self.theCollectionView.register(UINib(nibName: "SomeNibName", bundle: nil), forCellWithReuseIdentifier: "Some Identifier")
        self.longPressGesture = UILongPressGestureRecognizer(target: self, action: #selector(self.handleLongGesture(gesture:)))
        self.theCollectionView.addGestureRecognizer(longPressGesture)
    }

    fileprivate func moveDataItem(_ sIndex: Int, _ dIndex: Int) {
        let item = self.items.remove(at: sIndex)
        self.items.insert(item, at:dIndex)
        self.theCollectionView.reloadData()
    }

    @objc private func handleLongGesture(gesture: UILongPressGestureRecognizer) {
        switch(gesture.state) {
        case UIGestureRecognizerState.began:
            guard let selectedIndexPath = self.theCollectionView.indexPathForItem(at: gesture.location(in: self.theCollectionView)) else {
                break
            }
            self.theCollectionView.beginInteractiveMovementForItem(at: selectedIndexPath)

        case UIGestureRecognizerState.changed:
            guard let selectedIndexPath = self.theCollectionView.indexPathForItem(at: gesture.location(in: self.theCollectionView)) else {
                break
            }
            self.theCollectionView?.updateInteractiveMovementTargetPosition(gesture.location(in: gesture.view!))

        case UIGestureRecognizerState.ended:
            self.theCollectionView.endInteractiveMovement()
        default:
            self.theCollectionView.cancelInteractiveMovement()
        }
    }

}

// MARK: - UICollectionViewDelegateFlowLayout
extension LoveProfileEditViewViewController: UICollectionViewDelegateFlowLayout {

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: 88.0, height: collectionView.bounds.size.height)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsetsMake(0.0, 5.0, 0.0, 5.0)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 10.0
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return 10.0
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        return .zero
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
        return .zero
    }
}

// MARK: - UICollectionViewDataSource
extension LoveProfileEditViewViewController: UICollectionViewDataSource {
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return self.items.count
    }

    func collectionView(_ collectionView: UICollectionView, canMoveItemAt indexPath: IndexPath) -> Bool {
        //set boolean as per your need
        return true
    }

    func collectionView(_ collectionView: UICollectionView, moveItemAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {
        if sourceIndexPath.row > 0 && destinationIndexPath.row > 0 {
            self.moveDataItem(sourceIndexPath.row, destinationIndexPath.row)
        }
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Some Identifier", for: indexPath) as! SomeNibName
        cell.textLabel.text = self.items[indexPath.row]
        return cell
    }
}

Answer 3

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button addTarget:self action:@selector(imageTouch:withEvent:) 
forControlEvents:UIControlEventTouchDown];
[button addTarget:self action:@selector(imageMoved:withEvent:) 
forControlEvents:UIControlEventTouchDragInside];
[button setImage:[UIImage imageNamed:@"vehicle.png"] 
forState:UIControlStateNormal];
[self.view addSubview:button];

然后您可以通过响应 UIControlEventTouchDragInside 事件将车辆移动到您想要的任何位置，例如：

 - (IBAction) imageMoved:(id) sender withEvent:(UIEvent *) event
 {
CGPoint point = [[[event allTouches] anyObject] locationInView:self.view];
UIControl *control = sender;
control.center = point;
}