Swift-需要在自定义TableView单元格中单击并拖动UIImageView

Question

I am trying to create a custom TableViewController with a custom UITableViewCell class. I need to be able to drag and drop a photo inside the cell to a panel at the bottom of the view. I have tried a few ways to do this, but I am running into a couple of problems and haven't found a complete solution online:

First of all, after dragging and dropping I would like to return the UIImage view to the cell it came from.

Secondly, I am not able to cast a 'view' to my custom UITableViewClass outside the 'cellForRowAtIndexPath' method (so I will have access to the outlets I have set up.)

Here is my relevant code:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let thisCell:MealPlanTableViewCell = tableView.dequeueReusableCellWithIdentifier("mealPlanCell", forIndexPath: indexPath) as! MealPlanTableViewCell

    let meal = mealPlanElementArray[indexPath.row]

    thisCell.postTextLabel.text = meal.2
    thisCell.foodImageView.image = meal.4

    let gesture = UIPanGestureRecognizer(target: self, action: Selector("wasDragged:"))
    thisCell.foodImageView.addGestureRecognizer(gesture)
    thisCell.foodImageView.userInteractionEnabled = true

    return thisCell
}

func wasDragged(gesture: UIPanGestureRecognizer) {
    if calendarIsUp == calendarIsUp {
        let meal = gesture.view! as! UIImageView
        let sview = gesture.view!.superview!.superview!
        // CAN'T DO THE FOLLOWING -- CAN'T CAST TO CUSTOM CELL
        let mptvc:MealPlanTableViewCell = gesture.view!.superview!.superview! as! MealPlanTableViewCell

        if beginningDrag == true
        {


            beginningDrag = false

            // Move
            meal.superview?.superview?.superview?.superview?.superview?.superview?.superview?.addSubview(meal)

            beforeDragX = (meal.center.x)
            beforeDragY = (meal.bounds.maxY)

        }
        let translation = gesture.translationInView(self.view)

        meal.center = CGPoint(x: beforeDragX + translation.x, y: beforeDragY + translation.y)


        if gesture.state == UIGestureRecognizerState.Ended {

            beginningDrag = true
            // NEED TO ADD BACK TO custom UITableViewCell class.
            sview.addSubview(meal)
            meal.center = CGPoint(x: beforeDragX, y: beforeDragY)

        }
    }

Thanks for the help...

Answer 1

after dragging and dropping I would like to return the UIImage view to the cell it came from.

• Use the transform property to manipulate the position of the foodImageView .
• When the UIGestureRecognizer 's state == UIGestureRecognizerState.Ended , instantiate a new UIImageView and assign the foodImageView image to the new UIImageView 's image property.
• Add the new UIImageView to the desired view.
• Set the foodImageView 's transform to CGAffineTransformIdentity and animate it.

I'll leave the coding up to you as a learning exercise. For reference, here's a good explanation on CGAffineTransform: Demystifying CGAffineTransform .

I am not able to cast a 'view' to my custom UITableViewClass outside the 'cellForRowAtIndexPath' method (so I will have access to the outlets I have set up.)

Instead of adding the UIPanGestureRecognizer to the foodImageView add it to the custom UITableViewCell . Then, in your wasDragged function, access the UIGestureRecognizer.view , which is the custom UITableViewCell , and then access foodImageView property. This will eliminate the need to access the superview property at all. Accessing the superview property on UI elements in the UIKit framework is never a good idea because Apple can decide to change the structure of the view hierarchy whenever they wish. Ultimately, you are essentially guessing at which view you're going to be using and causing your future self headaches.

Ex.

func wasDragged(gesture: UIPanGestureRecognizer)
{
    if calendarIsUp == calendarIsUp
    {
        let cell = gesture.view! as! MealPlanTableViewCell

        if beginningDrag
        {
            beginningDrag = false

            beforeDragX = cell.foodImageView.center.x
            beforeDragY = cell.foodImageView.bounds.maxY

            // Move
            /*
                I have no idea what view this is so I don't know what to change it to.
            */
            cell.foodImageView.superview?.superview?.superview?.superview?.superview?.superview?.superview?.addSubview(cell.foodImageView)
        }

        let translation = gesture.translationInView(self.view)
        cell.foodImageView.center = CGPoint(x: beforeDragX + translation.x, y: beforeDragY + translation.y)

        if gesture.state == UIGestureRecognizerState.Ended
        {
            beginningDrag = true
            // NEED TO ADD BACK TO custom UITableViewCell class.
            cell.contentView.addSubview(cell.foodImageView)
            cell.foodImageView.center = CGPoint(x: beforeDragX, y: beforeDragY)

        }
    }
}