How do you move the uiimage inside the uiimageview to the right while retaining the aspect ratio of the original image? - swift

Question

I want to move an image to the right when a user imports it using uiimagepicker but when I set content mode = .right this occurs: The image enlarges for some reason and it looks like it moves to the left
Is there any way to keep the aspect ratio of the uiimageview and the aspect ratio of the imported image, and while also moving it to the right inside the image view.
This is how I want it to be

Answer 1

Here is one approach: custom view, using a sublayer with the content set to the image...
add a CALayer as a sublayer
calculate the aspect-scaled rectangle for the image inside the view's bounds
set the image layer's frame to that scaled rect
then set the layer's origin based on the desired alignment
A simple example:
class AspectAlignImageView: UIView {
enum AspectAlign {
case top, left, right, bottom, center
}
// this is an array so we can set two options
// if, for example, we don't know if the image will be
// taller or narrower
// for example:
// [.top, .right] will put a
// wide image aligned top
// narrow image aligned right
public var alignment: [AspectAlign] = [.center]
public var image: UIImage?
private let imgLayer: CALayer = CALayer()
override func layoutSubviews() {
super.layoutSubviews()
// make sure we have an image
if let img = image {
// only add the sublayer once
if imgLayer.superlayer == nil {
layer.addSublayer(imgLayer)
}
imgLayer.contentsGravity = .resize
imgLayer.contents = img.cgImage
// calculate the aspect-scaled rect inside our bounds
var scaledImageRect = CGRect.zero
let aspectWidth:CGFloat = bounds.width / img.size.width
let aspectHeight:CGFloat = bounds.height / img.size.height
let aspectRatio:CGFloat = min(aspectWidth, aspectHeight)
scaledImageRect.size.width = img.size.width * aspectRatio
scaledImageRect.size.height = img.size.height * aspectRatio
// set image layer frame to aspect-scaled rect
imgLayer.frame = scaledImageRect
// align as specified
if alignment.contains(.top) {
imgLayer.frame.origin.y = 0
}
if alignment.contains(.left) {
imgLayer.frame.origin.x = 0
}
if alignment.contains(.bottom) {
imgLayer.frame.origin.y = bounds.maxY - scaledImageRect.height
}
if alignment.contains(.right) {
imgLayer.frame.origin.x = bounds.maxX - scaledImageRect.width
}
}
}
}
class TestAlignViewController: UIViewController {
let testView = AspectAlignImageView()
override func viewDidLoad() {
super.viewDidLoad()
testView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(testView)
NSLayoutConstraint.activate([
// constrain test view 240x240 square
testView.widthAnchor.constraint(equalToConstant: 240.0),
testView.heightAnchor.constraint(equalTo: testView.widthAnchor),
// centered in view
testView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
testView.centerYAnchor.constraint(equalTo: view.centerYAnchor),
])
if let img = UIImage(named: "bottle") {
testView.image = img
}
testView.alignment = [.right]
// so we can see the actual view frame
testView.backgroundColor = .green
}
}
Using this image:
in a 240x240 view (view background set green so we can see its frame), we get this result:

Answer 2

Set your UIImage Content mode to aspect fill or aspect fit. Then use auto layout.