Dynamically changing height of the tableViewCell for images using UITableViewAutomaticDimension - swift

Question

I want to dynamically change the height of the cell such that the image fills the imageView in the width and the image maintains the aspect ratio.
I am trying to do this using UITableViewAutomaticDimension. Based on tutorials available online, this seemed to be a straightforward task. But in my case, the height of the cell doesn't adjust to perform this task. Either the image fills with aspect ratio leaving a lot of width space empty or fills the width but clips the part of the image vertically. I made sure there are leading, trailing, top and bottom constraints with respect to the cell view and also the tableView.rowHeight = UITableViewAutomaticDimension and table.estimatedRowHeight is set in viewDidLoad. I have uploaded the project at this link. Could someone please suggest what could I be missing here?
Link to GitHub
import UIKit
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet weak var picTableView: UITableView!
let reuseidentifier = "dynamicCellTableViewCell"
let images = [UIImage(named: "feedImage1"), UIImage(named: "feedImage2"), UIImage(named: "feedImage3")]
override func viewDidLoad() {
super.viewDidLoad()
picTableView.rowHeight = UITableViewAutomaticDimension
picTableView.estimatedRowHeight = 1000
}
// MARK: Table View Data Source
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return images.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier(reuseidentifier, forIndexPath: indexPath) as! DynamicCellTableViewCell
cell.displayImageView.image = images[indexPath.row]
return cell
}
}

Answer 1

I figured the solution. UIImageView when used with UITableViewAutomaticDimension only looks for the UIImage's true width and height as the size. So UIImageView adjusts its height to respond to UIImage's original height and not the scaled height for scaled width (aspectFit) to match layout constraint.
So trick is to first change the width and height of the image to match the width and height that you need in the cell. Rest of the job will be done by UITableViewAutomaticDimension. Below is the updated cellForRowAtIndex function that works now. Thanks all for giving your inputs.
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier(reuseidentifier, forIndexPath: indexPath) as! DynamicCellTableViewCell
let image = images[indexPath.row]!
let newWidth = cell.displayImageView.frame.width
let scale = newWidth/image.size.width
let newHeight = image.size.height * scale
UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight))
image.drawInRect(CGRectMake(0, 0, newWidth, newHeight))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
cell.displayImageView.image = newImage
return cell
}

Answer 2

You need implement next method for UITableViewController:
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return 1000.0;
}
Inside the method, you must know what dimension will have each cell. You must know in advance what height will have each cell.
For example, you could create an array of CGFloat saving the height will have each row, and when height change, you can update this position in array and execude tableView.reloadData().
var arrayHeight:CGFloat?
//Now fill array with height of each cell
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return arrayHeight[indexPath.row];
}

Answer 3

cell.updateConstraintsIfNeeded()
cell.setNeedsUpdateConstraints()
add these two lines in the cellForRowAtIndexPath delegate method
And make sure that top, bottom, right, left, constraints are set in the storyboard