Animation with constraints in UITableViewCell launches incorrectly

问题

I am running into an issue where I animate the size of a simple UIView in a table cell by adjusting an autolayout constraint.

When I launch the table for the first time, everything is broken.

If I reload the table, it works beautifully.

It's a single view controller with only a few lines of code. Please download this demo project to see it in action.

Here's my code in my whole UIViewController:

import UIKit

class TableCell: UITableViewCell {
    @IBOutlet weak var constraintRedBarWidth: NSLayoutConstraint!
    @IBOutlet weak var labelTitle: UILabel!
    @IBOutlet weak var viewBarArea: UIView!
    @IBOutlet weak var viewRedBar: UIView!
}

class ViewController: UIViewController {
    @IBOutlet weak var tableView: UITableView!
    var tableData : [CGFloat] = [1, 0.90, 0.70, 0.80,0.50] //percentages

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

    @IBAction func btnReloadTable(sender: AnyObject) {
        tableView.reloadData()
    }

}

extension ViewController: UITableViewDelegate, UITableViewDataSource {

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return tableData.count
    }

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("TableCell") as! TableCell
        cell.labelTitle.text = "Item \(indexPath.row + 1)"
        cell.constraintRedBarWidth.constant = 1
        cell.layoutIfNeeded()
        cell.constraintRedBarWidth.constant = cell.viewBarArea.frame.width * tableData[indexPath.row]
        UIView.animateWithDuration(0.5, animations: {
            cell.layoutIfNeeded()
        })
        return cell
    }

}

viewBarArea is just the parent view of the red view and simply represents the possible max size of the bar.

回答1:

use this line cellForRowAtIndexPath thats it

let cell = tableView.dequeueReusableCellWithIdentifier("TableCell", forIndexPath: indexPath) as! TableCell

来源：https://stackoverflow.com/questions/34892039/animation-with-constraints-in-uitableviewcell-launches-incorrectly

标签

ios

swift

uitableview

autolayout