How can I get the height and width of an uiimage? - ios

From the URL Image in Mail
I'm adding image to mail view. It will show full image. But I want to calculate, proportionally change the height and width of the image.
How can I get the height and width of UIImage?

let heightInPoints = image.size.height
let heightInPixels = heightInPoints * image.scale
let widthInPoints = image.size.width
let widthInPixels = widthInPoints * image.scale

Use the size property on the UIImage instance. See the documentation for more details.

UIImage *img = [UIImage imageNamed:#"logo.png"];
CGFloat width = img.size.width;
CGFloat height = img.size.height;

Some of the anwsers above, don't work well when rotating device.
Try:
CGRect imageContent = self.myUIImage.bounds;
CGFloat imageWidth = imageContent.size.width;
CGFloat imageHeight = imageContent.size.height;

There are a lot of helpful solutions out there, but there is no simplified way with extension. Here is the code to solve the issue with an extension:
extension UIImage {
var getWidth: CGFloat {
get {
let width = self.size.width
return width
}
}
var getHeight: CGFloat {
get {
let height = self.size.height
return height
}
}
}

UIImageView *imageView = [[[UIImageView alloc]initWithImage:[UIImage imageNamed:#"MyImage.png"]]autorelease];
NSLog(#"Size of my Image => %f, %f ", [[imageView image] size].width, [[imageView image] size].height) ;

import func AVFoundation.AVMakeRect
let imageRect = AVMakeRect(aspectRatio: self.image!.size, insideRect: self.bounds)
x = imageRect.minX
y = imageRect.minY

let imageView: UIImageView = //this is your existing imageView
let imageViewHeight: CGFloat = imageView.frame.height
let imageViewWidth: CGFloat = imageView.frame.width

Related

Image not show properly, I want to show like Facebook image post

I have to tried all type of content mode, Third party and lots of googling.
But, not success for me.
I want to show like Facebook image post.
We are post image in facebook, facebook show properly images and fill the image very properly into image view.
Follow steps
setImage to UIImageView (with UIViewContentModeScaleAspectFit)
get imageSize (CGSize imageSize = imageView.image.size)
UIImageView resize. [imageView sizeThatFits:imageSize]
move position where you want.
CGSize imageSize = imageView.image.size;
[imageView sizeThatFits:imageSize];
CGPoint imageViewCenter = imageView.center;
imageViewCenter.x = CGRectGetMidX(self.contentView.frame);
[imageView setCenter:imageViewCenter];
set UIImageView size == image (ratio):
#IBOutlet weak var heightConstraint: NSLayoutConstraint!
#IBOutlet weak var widthConstraint: NSLayoutConstraint!
func setImage(image: UIImage) {
imageView.image = image
let screenSize = UIScreen.main.bounds.size
let imageAspectRatio = image.size.width / image.size.height
let screenAspectRatio = screenSize.width / screenSize.height
if imageAspectRatio > screenAspectRatio {
widthConstraint.constant = min(image.size.width, screenSize.width)
heightConstraint.constant = widthConstraint.constant / imageAspectRatio
}
else {
heightConstraint.constant = min(image.size.height, screenSize.height)
widthConstraint.constant = heightConstraint.constant * imageAspectRatio
}
view.layoutIfNeeded()
}
reference link AutoLayout: UIImageView and Aspect Fit content mode

How to crop a UIImageView to a new UIImage in 'aspect fill' mode?

I'm trying to crop a sub-image of a image view using an overlay UIView that can be positioned anywhere in the UIImageView. I'm borrowing a solution from a similar post on how to solve this when the UIImageView content mode is 'Aspect Fit'. That proposed solution is:
func computeCropRect(for sourceFrame : CGRect) -> CGRect {
let widthScale = bounds.size.width / image!.size.width
let heightScale = bounds.size.height / image!.size.height
var x : CGFloat = 0
var y : CGFloat = 0
var width : CGFloat = 0
var height : CGFloat = 0
var offSet : CGFloat = 0
if widthScale < heightScale {
offSet = (bounds.size.height - (image!.size.height * widthScale))/2
x = sourceFrame.origin.x / widthScale
y = (sourceFrame.origin.y - offSet) / widthScale
width = sourceFrame.size.width / widthScale
height = sourceFrame.size.height / widthScale
} else {
offSet = (bounds.size.width - (image!.size.width * heightScale))/2
x = (sourceFrame.origin.x - offSet) / heightScale
y = sourceFrame.origin.y / heightScale
width = sourceFrame.size.width / heightScale
height = sourceFrame.size.height / heightScale
}
return CGRect(x: x, y: y, width: width, height: height)
}
The problem is that using this solution when the image view is aspect fill causes the cropped segment to not line up exactly with where the overlay UIView was positioned. I'm not quite sure how to adapt this code to accommodate for Aspect Fill or reposition my overlay UIView so that it lines up 1:1 with the segment I'm trying to crop.
UPDATE Solved using Matt's answer below
class ViewController: UIViewController {
#IBOutlet weak var catImageView: UIImageView!
private var cropView : CropView!
override func viewDidLoad() {
super.viewDidLoad()
cropView = CropView(frame: CGRect(x: 0, y: 0, width: 45, height: 45))
catImageView.image = UIImage(named: "cat")
catImageView.clipsToBounds = true
catImageView.layer.borderColor = UIColor.purple.cgColor
catImageView.layer.borderWidth = 2.0
catImageView.backgroundColor = UIColor.yellow
catImageView.addSubview(cropView)
let imageSize = catImageView.image!.size
let imageViewSize = catImageView.bounds.size
var scale : CGFloat = imageViewSize.width / imageSize.width
if imageSize.height * scale < imageViewSize.height {
scale = imageViewSize.height / imageSize.height
}
let croppedImageSize = CGSize(width: imageViewSize.width/scale, height: imageViewSize.height/scale)
let croppedImrect =
CGRect(origin: CGPoint(x: (imageSize.width-croppedImageSize.width)/2.0,
y: (imageSize.height-croppedImageSize.height)/2.0),
size: croppedImageSize)
let renderer = UIGraphicsImageRenderer(size:croppedImageSize)
let _ = renderer.image { _ in
catImageView.image!.draw(at: CGPoint(x:-croppedImrect.origin.x, y:-croppedImrect.origin.y))
}
}
#IBAction func performCrop(_ sender: Any) {
let cropFrame = catImageView.computeCropRect(for: cropView.frame)
if let imageRef = catImageView.image?.cgImage?.cropping(to: cropFrame) {
catImageView.image = UIImage(cgImage: imageRef)
}
}
#IBAction func resetCrop(_ sender: Any) {
catImageView.image = UIImage(named: "cat")
}
}
The Final Result
Let's divide the problem into two parts:
Given the size of a UIImageView and the size of its UIImage, if the UIImageView's content mode is Aspect Fill, what is the part of the UIImage that fits into the UIImageView? We need, in effect, to crop the original image to match what the UIImageView is actually displaying.
Given an arbitrary rect within the UIImageView, what part of the cropped image (derived in part 1) does it correspond to?
The first part is the interesting part, so let's try it. (The second part will then turn out to be trivial.)
Here's the original image I'll use:
https://static1.squarespace.com/static/54e8ba93e4b07c3f655b452e/t/56c2a04520c64707756f4267/1455596221531/
That image is 1000x611. Here's what it looks like scaled down (but keep in mind that I'm going to be using the original image throughout):
My image view, however, will be 139x182, and is set to Aspect Fill. When it displays the image, it looks like this:
The problem we want to solve is: what part of the original image is being displayed in my image view, if my image view is set to Aspect Fill?
Here we go. Assume that iv is the image view:
let imsize = iv.image!.size
let ivsize = iv.bounds.size
var scale : CGFloat = ivsize.width / imsize.width
if imsize.height * scale < ivsize.height {
scale = ivsize.height / imsize.height
}
let croppedImsize = CGSize(width:ivsize.width/scale, height:ivsize.height/scale)
let croppedImrect =
CGRect(origin: CGPoint(x: (imsize.width-croppedImsize.width)/2.0,
y: (imsize.height-croppedImsize.height)/2.0),
size: croppedImsize)
So now we have solved the problem: croppedImrect is the region of the original image that is showing in the image view. Let's proceed to use our knowledge, by actually cropping the image to a new image matching what is shown in the image view:
let r = UIGraphicsImageRenderer(size:croppedImsize)
let croppedIm = r.image { _ in
iv.image!.draw(at: CGPoint(x:-croppedImrect.origin.x, y:-croppedImrect.origin.y))
}
The result is this image (ignore the gray border):
But lo and behold, that is the correct answer! I have extracted from the original image exactly the region portrayed in the interior of the image view.
So now you have all the information you need. croppedIm is the UIImage actually displayed in the clipped area of the image view. scale is the scale between the image view and that image. Therefore, you can easily solve the problem you originally proposed! Given any rectangle imposed upon the image view, in the image view's bounds coordinates, you simply apply the scale (i.e. divide all four of its attributes by scale) — and now you have the same rectangle as a portion of croppedIm.
(Observe that we didn't really need to crop the original image to get croppedIm; it was sufficient, in reality, to know how to perform that crop. The important information is the scale along with the origin of croppedImRect; given that information, you can take the rectangle imposed upon the image view, scale it, and offset it to get the desired rectangle of the original image.)
EDIT I added a little screencast just to show that my approach works as a proof of concept:
EDIT Also created a downloadable example project here:
https://github.com/mattneub/Programming-iOS-Book-Examples/blob/39cc800d18aa484d17c26ffcbab8bbe51c614573/bk2ch02p058cropImageView/Cropper/ViewController.swift
But note that I can't guarantee that URL will last forever, so please read the discussion above to understand the approach used.
Matt answered the question perfectly. I was creating a full-screen camera and had a need to make the final output match the full-screen preview. Offering here a compact extension of Matt's overall answer in Swift 5 for easy use by others. Recommend reading Matt's answer as it explains things very well.
extension UIImage {
func cropToRect(rect: CGRect) -> UIImage? {
var scale = rect.width / self.size.width
scale = self.size.height * scale < rect.height ? rect.height/self.size.height : scale
let croppedImsize = CGSize(width:rect.width/scale, height:rect.height/scale)
let croppedImrect = CGRect(origin: CGPoint(x: (self.size.width-croppedImsize.width)/2.0,
y: (self.size.height-croppedImsize.height)/2.0),
size: croppedImsize)
UIGraphicsBeginImageContextWithOptions(croppedImsize, true, 0)
self.draw(at: CGPoint(x:-croppedImrect.origin.x, y:-croppedImrect.origin.y))
let croppedImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return croppedImage
}
}

How to resize UIImageView based on UIImage's size/ratio in Swift 3?

I have a UIImageView and the user is able to download UIImages in various formats. The issue is that I need the UIImageView to resize based on the given Image's ratio.
Currently, I'm using Aspect fit, but the UIImageView remains empty on big parts of itself. I would like to have the UIImageView resize itself based on its content. E.g if the pic is 1:1, 4:3, 6:2, 16:9...
Help is very appreciated.
As requested, that is what I want:
I have had an UIImageView that was square, loaded with an Image in 16:7 or whatever, and the UIImageView resized to fit the size of the Image...
I spent many hours trying to find a solution to the same problem you're having and this is the only solution that worked for me (Swift 4, Xcode 9.2):
class ScaledHeightImageView: UIImageView {
override var intrinsicContentSize: CGSize {
if let myImage = self.image {
let myImageWidth = myImage.size.width
let myImageHeight = myImage.size.height
let myViewWidth = self.frame.size.width
let ratio = myViewWidth/myImageWidth
let scaledHeight = myImageHeight * ratio
return CGSize(width: myViewWidth, height: scaledHeight)
}
return CGSize(width: -1.0, height: -1.0)
}
}
Add the class to the project and set the UIImageView to the custom class ScaledHeightImageView. The image view's content mode is Aspect Fit.
My problem is the same as the one stated in this post. Inside my prototype TableViewCell's ContentView, I have a vertical StackView constrained to each edge. Inside the StackView there was a Label, ImageView and another Label. Having the ImageView set to AspectFit was not enough. The image would be the proper size and proportions but the ImageView didn't wrap the actual image leaving a bunch of extra space between the image and label (just like in the image above). The ImageView height seemed to match height of the original image rather than the height of the resized image (after aspectFit did it's job). Other solutions I found didn't completely resolve the problem for various reasons. I hope this helps someone.
I spent many hours on this, and I finally got a solution that worked for me (Swift 3):
in IB, I set UIImageView's 'Content Mode' to 'Aspect Fit'
in IB, I set UIImageView's width constraint to be equal to whatever you want (in my case, the view's width)
in IB, I set UIImageView's height constraint to be equal to 0, and create a referencing outlet for it (say, constraintHeight)
Then, when I need to display the image, I simply write the following (sampled from answers above):
let ratio = image.size.width / image.size.height
let newHeight = myImageView.frame.width / ratio
constraintHeight.constant = newHeight
view.layoutIfNeeded()
Basically, this ensures that the image fills the UIImageView's width and forces the UIImageView's height to be equal to the image's height after it scaled
It looks like you want to resize an ImageView according to the image ratio and the container view's size, here is the example in Swift (Sorry,the former answer with a bug, I fixed it):
let containerView = UIView(frame: CGRect(x:0,y:0,width:320,height:500))
let imageView = UIImageView()
if let image = UIImage(named: "a_image") {
let ratio = image.size.width / image.size.height
if containerView.frame.width > containerView.frame.height {
let newHeight = containerView.frame.width / ratio
imageView.frame.size = CGSize(width: containerView.frame.width, height: newHeight)
}
else{
let newWidth = containerView.frame.height * ratio
imageView.frame.size = CGSize(width: newWidth, height: containerView.frame.height)
}
}
SWIFT 5
This is what I have done in my project:
Place an ImageView in ViewController and create an outlet in viewDidLoad() named imageView.
override func viewDidLoad() {
super.viewDidLoad()
var image = UIImage(contentsOfFile: "yourFilePath")!
var aspectR: CGFloat = 0.0
aspectR = image.size.width/image.size.height
imageView.translatesAutoresizingMaskIntoConstraints = false
imageView.image = image
imageView.contentMode = .scaleAspectFit
NSLayoutConstraint.activate([
imageView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
imageView.centerYAnchor.constraint(equalTo: view.centerYAnchor),
imageView.leadingAnchor.constraint(greaterThanOrEqualTo: view.leadingAnchor),
imageView.trailingAnchor.constraint(lessThanOrEqualTo: view.trailingAnchor),
imageView.heightAnchor.constraint(equalTo: imageView.widthAnchor, multiplier: 1/aspectR)
])
}
The last 3 lines of NSLayoutConstraint.activate array ensures that the image width stays within the bounds of the container view and the height stays in proportion to width (i.e. the aspect ratio is maintained and height of imageView is shrunk to minimum required value).
View Controller in Interface Builder: Main.storyboard
Snapshot of UIImageView in running app: appSnapshot
The solution I used is based on olearyj234's solution, but makes having no image take up essentially no space (or more specifically the minimum iOS will accept). It also uses ceil to avoid problems which can occur with non-integer values when UIImageView's are embedded in things like scrolling cells.
class FixedWidthAspectFitImageView: UIImageView
{
override var intrinsicContentSize: CGSize
{
// VALIDATE ELSE RETURN
// frameSizeWidth
let frameSizeWidth = self.frame.size.width
// image
// ⓘ In testing on iOS 12.1.4 heights of 1.0 and 0.5 were respected, but 0.1 and 0.0 led intrinsicContentSize to be ignored.
guard let image = self.image else
{
return CGSize(width: frameSizeWidth, height: 1.0)
}
// MAIN
let returnHeight = ceil(image.size.height * (frameSizeWidth / image.size.width))
return CGSize(width: frameSizeWidth, height: returnHeight)
}
}
The solution is also based on olearyj234's solution, but I think this will help more people.
#IBDesignable
class DynamicImageView: UIImageView {
#IBInspectable var fixedWidth: CGFloat = 0 {
didSet {
invalidateIntrinsicContentSize()
}
}
#IBInspectable var fixedHeight: CGFloat = 0 {
didSet {
invalidateIntrinsicContentSize()
}
}
override var intrinsicContentSize: CGSize {
var size = CGSize.zero
if fixedWidth > 0 && fixedHeight > 0 { // 宽高固定
size.width = fixedWidth
size.height = fixedHeight
} else if fixedWidth <= 0 && fixedHeight > 0 { // 固定高度动态宽度
size.height = fixedHeight
if let image = self.image {
let ratio = fixedHeight / image.size.height
size.width = image.size.width * ratio
}
} else if fixedWidth > 0 && fixedHeight <= 0 { // 固定宽度动态高度
size.width = fixedWidth
if let image = self.image {
let ratio = fixedWidth / image.size.width
size.height = image.size.height * ratio
}
} else { // 动态宽高
size = image?.size ?? .zero
}
return size
}
}
A lot of the answers here are using the frame when calculating the intrinsicContentSize. The docs discourage this:
This intrinsic size must be independent of the content frame, because there’s no way to dynamically communicate a changed width to the layout system based on a changed height, for example.
I've found wanting the UIImageView height to be dynamically set according to:
the aspect ratio of the image
a fixed width
to be a common problem, I provide a possible solution below.
Solution
I think this is best solved by adding an NSLayoutConstraint to the UIImageView which constrains the widthAnchor and heightAnchor (or vice versa) such that the multiplier matches the aspect ratio of the image. I have created a UIImageView subclass that does exactly this:
import UIKit
/// `AdjustableImageView` is a `UIImageView` which should have a fixed width or height.
/// It will add an `NSLayoutConstraint` such that it's width/height (aspect) ratio matches the
/// `image` width/height ratio.
class AdjustableImageView: UIImageView {
/// `NSLayoutConstraint` constraining `heightAnchor` relative to the `widthAnchor`
/// with the same `multiplier` as the inverse of the `image` aspect ratio, where aspect
/// ratio is defined width/height.
private var aspectRatioConstraint: NSLayoutConstraint?
/// Override `image` setting constraint if necessary on set
override var image: UIImage? {
didSet {
updateAspectRatioConstraint()
}
}
// MARK: - Init
override init(image: UIImage?) {
super.init(image: image)
setup()
}
override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setup()
}
// MARK: - Setup
/// Shared initializer code
private func setup() {
// Set default `contentMode`
contentMode = .scaleAspectFill
// Update constraints
updateAspectRatioConstraint()
}
// MARK: - Resize
/// De-active `aspectRatioConstraint` and re-active if conditions are met
private func updateAspectRatioConstraint() {
// De-active old constraint
aspectRatioConstraint?.isActive = false
// Check that we have an image
guard let image = image else { return }
// `image` dimensions
let imageWidth = image.size.width
let imageHeight = image.size.height
// `image` aspectRatio
guard imageWidth > 0 else { return }
let aspectRatio = imageHeight / imageWidth
guard aspectRatio > 0 else { return }
// Create a new constraint
aspectRatioConstraint = heightAnchor.constraint(
equalTo: widthAnchor,
multiplier: aspectRatio
)
// Activate new constraint
aspectRatioConstraint?.isActive = true
}
}
In case the Content mode is set aspectFit or aspectFill the answer would vary:
extension UIImageView {
var intrinsicScaledContentSize: CGSize? {
switch contentMode {
case .scaleAspectFit:
// aspect fit
if let image = self.image {
let imageWidth = image.size.width
let imageHeight = image.size.height
let viewWidth = self.frame.size.width
let ratio = viewWidth/imageWidth
let scaledHeight = imageHeight * ratio
return CGSize(width: viewWidth, height: scaledHeight)
}
case .scaleAspectFill:
// aspect fill
if let image = self.image {
let imageWidth = image.size.width
let imageHeight = image.size.height
let viewHeight = self.frame.size.width
let ratio = viewHeight/imageHeight
let scaledWidth = imageWidth * ratio
return CGSize(width: scaledWidth, height: imageHeight)
}
default: return self.bounds.size
}
return nil
}
}
Set your imageView to aspectFit, that will resize the image to not exceed your imageView's frame.
You can get the size of your UIImage of your imageView with logic from this question - basically just get the height and width of the UIImage.
Calculate the ratio and set the width/height of the imageView to fit you screen.
There is also a similar question to your that you might get you answer from.
I modified #user8969729 's solution to replace the "fixed" width/height with "max", thus more like #JoshuaHart's solution. Handle the maxWidth == 0 / maxHeight == 0 case as you wish, since I always had both set I just quickly ignored that case.
public class AdjustsViewBoundsImageView: UIImageView {
/// The maximum width that you want this imageView to grow to.
#objc dynamic var maxWidth: CGFloat = 0 {
didSet {
invalidateIntrinsicContentSize()
}
}
/// The maximum height that you want this imageView to grow to.
#objc dynamic var maxHeight: CGFloat = 0 {
didSet {
invalidateIntrinsicContentSize()
}
}
private var maxAspectRatio: CGFloat { return maxWidth / maxHeight }
override public var intrinsicContentSize: CGSize {
guard let classImage = self.image else { return super.intrinsicContentSize }
if maxHeight == 0 || maxWidth == 0 {
return super.intrinsicContentSize
}
let imageWidth = classImage.size.width
let imageHeight = classImage.size.height
let aspectRatio = imageWidth / imageHeight
// Width is greater than height, return max width image and new height.
if imageWidth > imageHeight {
let newHeight = maxWidth/aspectRatio
return CGSize(width: maxWidth, height: newHeight)
}
// Height is greater than width, return max height and new width.
if imageHeight > imageWidth {
// If the aspect ratio is larger than our max ratio, then using max width
// will be hit before max height.
if aspectRatio > maxAspectRatio {
let newHeight = maxWidth/aspectRatio
return CGSize(width: maxWidth, height: newHeight)
}
let newWidth = maxHeight * aspectRatio
return CGSize(width: newWidth, height: maxHeight)
}
// Square image, return the lesser of max width and height.
let squareMinimumValue = min(maxWidth, maxHeight)
return CGSize(width: squareMinimumValue, height: squareMinimumValue)
}
}
If you want scale UIImageView by width and height - use this class:
import UIKit
class AutoSizeImageView: UIImageView {
#IBInspectable var maxSize: CGFloat = 100
// MARK: Methods
func updateSize() {
let newSize = getSize()
snp.remakeConstraints { make in
make.width.equalTo(newSize.width)
make.height.equalTo(newSize.height)
}
}
private func getSize() -> CGSize {
guard let image = image else { return .zero }
if image.size.width == image.size.height { return CGSize(width: maxSize, height: maxSize) }
if image.size.width > image.size.height {
let widthRatio = maxSize / image.size.width
let scaledHeight = image.size.height * widthRatio
return CGSize(width: maxSize, height: scaledHeight)
}
let heightRatio = maxSize / image.size.height
let scaledWidth = image.size.width * heightRatio
return CGSize(width: scaledWidth, height: maxSize)
}
}
Call it like this:
#IBOutlet weak var imageView: AutoSizeImageView!
imageView.image = image
imageView.updateSize()
Please note I've used SnapKit to manage constraints:
snp.remakeConstraints { make in
make.width.equalTo(newSize.width)
make.height.equalTo(newSize.height)
}
Change solution for Merricat.
Hi. Use your solution in collection view cell, make onboarding. First launch and scroll not not give right height. I add this -
contentView.layoutIfNeeded()
if let image = UIImage(named: "\(data.imageName)") {
let ratio = image.size.width / image.size.height
let newHeight = imageView.frame.width / ratio
imageView.image = image
imageHeightConstraint.priority = .defaultHigh
imageHeightConstraint.constant = newHeight
contentView.layoutIfNeeded()
}
SWIFT 5 CLASS
This can easily be converted to use IBOutlets if desired. My use-case involved programmatically adding imageViews. This is very reliable. Just create a new file in your project and add the code below.
import UIKit
/// Resizeable Image View that takes a max height and max width
/// Will resize the imageView to best fit for the aspect ratio of the image,
/// With the given space provided.
public class ResizeableImageView: UIImageView {
private var widthConstraint: NSLayoutConstraint?
private var heightConstraint: NSLayoutConstraint?
// MARK: - INITIALIZERS:
public override init(image: UIImage?) {
super.init(image: image)
}
/// Given the max width and height, resizes the imageView to fit the image.
/// - IMPORTANT: This subclass adds a height and width constraint.
/// - Parameters:
/// - image: (UIImage?) The image to add to the imageView.
/// - maxWidth: (CGFloat) The max width you would like the imageView to grow to.
/// - maxHeight: (CGFloat) The max height you would like the imageView to grow to.
convenience init(image: UIImage?, maxWidth: CGFloat, maxHeight: CGFloat) {
self.init(image: image)
widthConstraint = constrain(width: maxWidth)
heightConstraint = constrain(height: maxHeight)
}
#available (*, unavailable) required internal init?(coder aDecoder: NSCoder) { nil }
// MARK: - VARIABLES:
/// The maximum width that you want this imageView to grow to.
private var maxWidth: CGFloat {
get { widthConstraint?.constant ?? 0 }
set { widthConstraint?.constant = newValue }
}
/// The maximum height that you want this imageView to grow to.
private var maxHeight: CGFloat {
get { heightConstraint?.constant ?? 0 }
set { heightConstraint?.constant = newValue }
}
private var maxAspectRatio: CGFloat { maxWidth / maxHeight }
override public var intrinsicContentSize: CGSize {
guard let classImage = self.image else { return frame.size }
let imageWidth = classImage.size.width
let imageHeight = classImage.size.height
let aspectRatio = imageWidth / imageHeight
// Width is greater than height, return max width image and new height.
if imageWidth > imageHeight {
let newHeight = maxWidth/aspectRatio
self.widthConstraint?.constant = maxWidth
self.heightConstraint?.constant = newHeight
return CGSize(width: maxWidth, height: newHeight)
}
// Height is greater than width, return max height and new width.
if imageHeight > imageWidth {
// If the aspect ratio is larger than our max ratio, then using max width
// will be hit before max height.
if aspectRatio > maxAspectRatio {
let newHeight = maxWidth/aspectRatio
self.widthConstraint?.constant = maxWidth
self.heightConstraint?.constant = newHeight
return CGSize(width: maxWidth, height: newHeight)
}
let newWidth = maxHeight * aspectRatio
self.widthConstraint?.constant = newWidth
self.heightConstraint?.constant = maxHeight
return CGSize(width: newWidth, height: maxHeight)
}
// Square image, return the lesser of max width and height.
let squareMinimumValue = min(maxWidth, maxHeight)
self.widthConstraint?.constant = squareMinimumValue
self.heightConstraint?.constant = squareMinimumValue
return CGSize(width: squareMinimumValue, height: squareMinimumValue)
}
}
Example Usage:
let imageView = ResizeableImageView(image: image, maxWidth: 250, maxHeight: 250)

How to center multiple images in scrollview in Xcode/Swift

I am trying to horizontally center 30 images in a scrollview. What is the best approach to do so? Thanks.
EDIT: Programmatically I was able to create the images, thanks to David Cao, but I am still having the issue of it not centering. Thanks.
If they're all the same image, why not do this programmatically? Just make a for loop and iterate through the bounds.
NSInteger numWidth = 3;
NSInteger numHeight = 10;
CGFloat border = 8;
CGFloat width = (self.scrollView.frame.size.width - (numWidth + 1) * border)/3;
for (NSInteger i = 0; i < numWidth; ++i) {
for (NSInteger j = 0; j < numHeight; ++j) {
UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"imageNameHere"]];
imageView.frame = CGRectMake(border + width*i, border + width*j, width, width);
[self.scrollView addSubview:imageView];
}
}
[self.scrollView setContentSize:CGSizeMake(self.scrollView.frame.size.width, (border + width)*numHeight + border];
I was able to solve this problem. I modified David Cao's code to account for various screen widths using
let screenSize: CGRect = UIScreen.mainScreen().bounds
let screenWidth = screenSize.width`
I adjusted the scrollView frame size width to equal the screenWidth. Removing the border variable fit my need for fitting the screen perfectly.
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let screenSize: CGRect = UIScreen.mainScreen().bounds
let screenWidth = screenSize.width
//let screenHeight = screenSize.height
let numWidth: CGFloat = 3
let numHeight: CGFloat = 10
self.scrollView.frame.size.width = screenWidth
let width: CGFloat = (self.scrollView.frame.size.width - (numWidth + 1))/3
for var i:CGFloat = 0; i < 3; ++i{
for var j:CGFloat = 0; j < 10; ++j {
let image: UIImage = UIImage(named: "image1.png")!
imageView = UIImageView(image: image)
imageView!.frame = CGRectMake(width*i, width*j, width, width)
self.scrollView.addSubview(imageView!)
}
}
scrollView.contentSize.height = (width)*numHeight
Thank you all for the help!

UIImage aspect fit and align to top

It looks like aspect fit aligns the image to the bottom of the frame by default. Is there a way to override the alignment while keeping aspect fit intact?
** EDIT **
This question predates auto layout. In fact, auto layout was being revealed in WWDC 2012 the same week this question was asked
In short, you cannot do this with a UIImageView.
One solution is to subclass a UIView containing an UIImageView and change its frame according to image size. For example, you can find one version here.
Set the UIImageView's bottom layout constraint priority to lowest (i.e. 250) and it will handle it for you.
The way to do this is to modify the contentsRect of the UIImageView layer. The following code from my project (sub class of UIImageView) assumes scaleToFill and offsets the image such that it aligns top, bottom, left or right instead of the default center alignment. For aspectFit is would be a similar solution.
typedef NS_OPTIONS(NSUInteger, AHTImageAlignmentMode) {
AHTImageAlignmentModeCenter = 0,
AHTImageAlignmentModeLeft = 1 << 0,
AHTImageAlignmentModeRight = 1 << 1,
AHTImageAlignmentModeTop = 1 << 2,
AHTImageAlignmentModeBottom = 1 << 3,
AHTImageAlignmentModeDefault = AHTImageAlignmentModeCenter,
};
- (void)updateImageViewContentsRect {
CGRect imageViewContentsRect = CGRectMake(0, 0, 1, 1);
if (self.image.size.height > 0 && self.bounds.size.height > 0) {
CGRect imageViewBounds = self.bounds;
CGSize imageSize = self.image.size;
CGFloat imageViewFactor = imageViewBounds.size.width / imageViewBounds.size.height;
CGFloat imageFactor = imageSize.width / imageSize.height;
if (imageFactor > imageViewFactor) {
//Image is wider than the view, so height will match
CGFloat scaledImageWidth = imageViewBounds.size.height * imageFactor;
CGFloat xOffset = 0.0;
if (BM_CONTAINS_BIT(self.alignmentMode, AHTImageAlignmentModeLeft)) {
xOffset = -(scaledImageWidth - imageViewBounds.size.width) / 2;
} else if (BM_CONTAINS_BIT(self.alignmentMode, AHTImageAlignmentModeRight)) {
xOffset = (scaledImageWidth - imageViewBounds.size.width) / 2;
}
imageViewContentsRect.origin.x = (xOffset / scaledImageWidth);
} else if (imageFactor < imageViewFactor) {
CGFloat scaledImageHeight = imageViewBounds.size.width / imageFactor;
CGFloat yOffset = 0.0;
if (BM_CONTAINS_BIT(self.alignmentMode, AHTImageAlignmentModeTop)) {
yOffset = -(scaledImageHeight - imageViewBounds.size.height) / 2;
} else if (BM_CONTAINS_BIT(self.alignmentMode, AHTImageAlignmentModeBottom)) {
yOffset = (scaledImageHeight - imageViewBounds.size.height) / 2;
}
imageViewContentsRect.origin.y = (yOffset / scaledImageHeight);
}
}
self.layer.contentsRect = imageViewContentsRect;
}
Swift version
class AlignmentImageView: UIImageView {
enum HorizontalAlignment {
case left, center, right
}
enum VerticalAlignment {
case top, center, bottom
}
// MARK: Properties
var horizontalAlignment: HorizontalAlignment = .center
var verticalAlignment: VerticalAlignment = .center
// MARK: Overrides
override var image: UIImage? {
didSet {
updateContentsRect()
}
}
override func layoutSubviews() {
super.layoutSubviews()
updateContentsRect()
}
// MARK: Content layout
private func updateContentsRect() {
var contentsRect = CGRect(origin: .zero, size: CGSize(width: 1, height: 1))
guard let imageSize = image?.size else {
layer.contentsRect = contentsRect
return
}
let viewBounds = bounds
let imageViewFactor = viewBounds.size.width / viewBounds.size.height
let imageFactor = imageSize.width / imageSize.height
if imageFactor > imageViewFactor {
// Image is wider than the view, so height will match
let scaledImageWidth = viewBounds.size.height * imageFactor
var xOffset: CGFloat = 0.0
if case .left = horizontalAlignment {
xOffset = -(scaledImageWidth - viewBounds.size.width) / 2
}
else if case .right = horizontalAlignment {
xOffset = (scaledImageWidth - viewBounds.size.width) / 2
}
contentsRect.origin.x = xOffset / scaledImageWidth
}
else {
let scaledImageHeight = viewBounds.size.width / imageFactor
var yOffset: CGFloat = 0.0
if case .top = verticalAlignment {
yOffset = -(scaledImageHeight - viewBounds.size.height) / 2
}
else if case .bottom = verticalAlignment {
yOffset = (scaledImageHeight - viewBounds.size.height) / 2
}
contentsRect.origin.y = yOffset / scaledImageHeight
}
layer.contentsRect = contentsRect
}
}
this will make the image fill the width and occupy only the height it needs to fit the image (widthly talking)
swift 4.2:
let image = UIImage(named: "my_image")!
let ratio = image.size.width / image.size.height
cardImageView.widthAnchor
.constraint(equalTo: cardImageView.heightAnchor, multiplier: ratio).isActive = true
I had similar problem.
Simplest way was to create own subclass of UIImageView. I add for subclass 3 properties so now it can be use easly without knowing internal implementation:
#property (nonatomic) LDImageVerticalAlignment imageVerticalAlignment;
#property (nonatomic) LDImageHorizontalAlignment imageHorizontalAlignment;
#property (nonatomic) LDImageContentMode imageContentMode;
You can check it here:
https://github.com/LucasssD/LDAlignmentImageView
Add the Aspect Ratio constraint with your image proportions.
Do not pin UIImageView to bottom.
If you want to change the UIImage dynamically remember to update aspect ratio constraint.
I solved this natively in Interface Builder by setting a constraint on the height of the UIImageView, since the image would always be 'pushed' up when the image was larger than the screen size.
More specifically, I set the UIImageView to be the same height as the View it is in (via height constraint), then positioned the UIImageView with spacing constraints in IB. This results in the UIImageView having an 'Aspect Fit' which still respects the top spacing constraint I set in IB.
If you are able to subclass UIImageView, then you can just override the image var.
override var image: UIImage? {
didSet {
self.sizeToFit()
}
}
In Objective-C you can do the same thing by overriding the setter.

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