Q:

Swift, custom UITableViewCell with UIImageView. Need to resize cell to image height

I'am trying to make app, that will show images in table view.
I have custom cell with image view. It only must download image data from url: 
@IBOutlet weak var tweetImage: UIImageView!
var imageData : MediaItem? { didSet { updateUI() }}

func updateUI(){
    tweetImage.image = nil
    if let url = imageData?.url {
        if let data = NSData(contentsOfURL: url) {
            tweetImage.image = UIImage(data: data)
        }
    }
}

I need to get the cell height was changed after the download. It must be equal to the height of the image. I set auto dimension in viewController:
override func viewDidLoad() {
        super.viewDidLoad()
        tableView.estimatedRowHeight = tableView.rowHeight
        tableView.rowHeight = UITableViewAutomaticDimension
    }

I set "aspect fit" to image, I get strange results. The image extends beyond the boundaries of the cell. Maybe i need to set some constraints... I don't know.
Results:

But i need this:

A:

If you want to load images async:
After you load and set new UIImage, you can reload specific cell via UITableView function:
- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation
In your UIViewController:
override func viewDidLoad() {
    super.viewDidLoad()
    tableView.estimatedRowHeight = tableView.rowHeight
    tableView.rowHeight = UITableViewAutomaticDimension
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "imageDidLoadNotification:", name:"CellDidLoadImageDidLoadNotification", object: nil)
}

func imageDidLoadNotification(notification: NSNotification) {
    if  let cell = notification.object as? UITableViewCell
        let indexPath = tableView.indexPathForCell(cell) {
        tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.None)
    }
}

In your UITableViewCell
func updateUI(){
    tweetImage.image = nil
    if let url = imageData?.url {
        if let data = NSData(contentsOfURL: url) {
            tweetImage.image = UIImage(data: data)
            NSNotificationCenter.defaultCenter().postNotificationName("CellDidLoadImageDidLoadNotification", object: self)
        }
    }
}

