如何调整UIImageView的大小并强制父UITableViewCell的重新布局

Question

I have custom TableViewCells that have UITableViewAutomaticDimension. When I load an image into the cell, it's almost always much too tall for the image, and I end up with large white bars above and below the image. What I am attempting to do is resize the UIImageView to be the same size as the image, but nothing will work.

I also tried creating a new UIImageView and setting that up, but UIImageView.init(frame: CGRectMake(...) ) returns nil for some reason. My Google-fu is failing me on this one.

My code for (attempting) to resize the imageView and parent cell: (note that i is my new image and cell.postImage is an IBOutlet of type UIImageView! )

let oFrame = cell.postImage.frame
let width = oFrame.width
let height = (i.size.height / i.size.width) * width
cell.postImage.frame = CGRectMake(oFrame.origin.x, oFrame.origin.y, width, height)
cell.postImage.contentMode = .ScaleAspectFit
cell.postImage.image = i
cell.setNeedsUpdateConstraints()
cell.setNeedsLayout()
cell.layoutIfNeeded()

Answer 1

Set the width constraint for postImage. Create an IBOutlet for the height constraint of postImage. Then in say something like:

let oFrame = cell.postImage.frame
let width = oFrame.width
let height = (i.size.height / i.size.width) * width
cell.postImageHeightConstraint.constant = height

And it looks like you want the image center so align center x.