ios - 删除 UILongPressGesture 默认 Action

Question

我有一个设置，允许用户打开和关闭 UITableView 单元格上的 UILongPressGesture。我有一个简单的 bool 值，我正在检查是否应该添加或删除手势。

    // Gesture Recognizer
    let longPress: UILongPressGestureRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(longPressDetected(_:)))

    if(options?.alphaOrder == false){
        self.tableView.addGestureRecognizer(longPress)
    }
    else{
        self.tableView.removeGestureRecognizer(longPress)
    }

长按方法

func longPressDetected(_ sender: Any){

    let longPress:UILongPressGestureRecognizer = sender as! UILongPressGestureRecognizer
    let state:UIGestureRecognizerState = longPress.state

    let location:CGPoint = longPress.location(in: self.tableView) as CGPoint
    let indexPath = self.tableView.indexPathForRow(at: location)

    var snapshot:UIView!
    var sourceIndexPath:NSIndexPath?

    if (holderView) != nil{
        snapshot = holderView
    }

    if (beginningIndexPath) != nil{
        sourceIndexPath = beginningIndexPath
    }


    switch(state){

        case UIGestureRecognizerState.began:
            if let test = indexPath{
                sourceIndexPath = indexPath! as NSIndexPath
                beginningIndexPath = sourceIndexPath
                let cell:UITableViewCell = self.tableView.cellForRow(at: test)!
                snapshot = self.customSnapShotFrom(view: cell)
                holderView = snapshot

                var center:CGPoint = cell.center
                snapshot.center = center
                snapshot.alpha = 0.0
                self.tableView.addSubview(snapshot)

                UIView.animate(withDuration: 0.25, animations:{
                    center.y = location.y
                    snapshot.center = center
                    snapshot.transform = CGAffineTransform(scaleX: 1.05, y: 1.05)
                    snapshot.alpha = 0.98
                    cell.alpha = 0.0
                },completion:{ _ in
                    cell.isHidden = true})
            }
        break

        case UIGestureRecognizerState.changed:
            // print("changed")
            var center:CGPoint = snapshot.center
            center.y = location.y
            snapshot.center = center

            if let test = indexPath {

                let bool = indexPath!.elementsEqual(beginningIndexPath as IndexPath)

                if !bool {

                    self.updatePriorities(draggedOverIndexPath: test as NSIndexPath)

                }
            }
        default:
            // print("finished")
            let cell:UITableViewCell = self.tableView.cellForRow(at: sourceIndexPath as! IndexPath)!
            cell.isHidden = false
            cell.alpha = 0.0


            UIView.animate(withDuration: 0.25, animations: {


                snapshot.center = cell.center;
                snapshot.transform = .identity
                snapshot.alpha = 0.0;
                cell.alpha = 1.0;

            }, completion: { _ in

                sourceIndexPath = nil
                snapshot.removeFromSuperview()
                snapshot = nil
            })

        }
}

    func customSnapShotFrom(view:UIView) -> UIView {

    let snapshot:UIView = view.snapshotView(afterScreenUpdates: true)!
    snapshot.layer.masksToBounds = false;
    snapshot.layer.cornerRadius = 0.0;
    snapshot.layer.shadowOffset = CGSize(width: 2.0, height: 2.0);
    snapshot.layer.shadowRadius = 4.0;
    snapshot.layer.shadowOpacity = 1.0;

    return snapshot;
}


func updatePriorities(draggedOverIndexPath:NSIndexPath) {
    let firstItem: Person = fetchedResultsController.object(at: beginningIndexPath as IndexPath)
    let secondItem: Person = fetchedResultsController.object(at: draggedOverIndexPath as IndexPath)

    firstItem.priority = Int32(draggedOverIndexPath.row)
    secondItem.priority = Int32(beginningIndexPath.row)

    beginningIndexPath = draggedOverIndexPath

    coreDataStack.saveContext()

}

这有效，但我注意到即使手势被删除，我仍然可以长按表格单元格并移动它。它不会重新排列表格单元格，但我想阻止这种情况发生。

Answer 1

这里有一些半伪代码，展示了我推荐的内容。这更好，因为每次 viewWillAppear 都会更新 GestureRecognizer。

class CustomViewController: UIViewController {
    var longPress: UILongPressGestureRecognizer

    required init() {
        super.init(nibName: nil, bundle: nil)
        longPress = UILongPressGestureRecognizer(target: self, action: #selector(longPressDetected(_:)))
        self.tableView.addGestureRecognizer(longPress)
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        longPress.isEnabled = (options?.alphaOrder == false)
    }


    func longPressDetected(_ sender: Any) {
        ...existing method...
    }
}