How to rotate image in Swift?

Question

I am unable to rotate the image by 90 degrees in swift. I have written below code but there is an error and doesn't compile

  func imageRotatedByDegrees(oldImage: UIImage, deg degrees: CGFloat) -> UIImage {

    //Calculate the size of the rotated view's containing box for our drawing space
    let rotatedViewBox: UIView = UIView(frame: CGRect(x: 0, y: 0, width: oldImage.size.width, height: oldImage.size.height))
    let t: CGAffineTransform = CGAffineTransform(rotationAngle: degrees * CGFloat(M_PI / 180))
    rotatedViewBox.transform = t
    let rotatedSize: CGSize = rotatedViewBox.frame.size

    //Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize)
    let bitmap: CGContext = UIGraphicsGetCurrentContext()!

    //Move the origin to the middle of the image so we will rotate and scale around the center.
    bitmap.translateBy(x: rotatedSize.width / 2, y: rotatedSize.height / 2)

    //Rotate the image context
    bitmap.rotate(by: (degrees * CGFloat(M_PI / 180)))

    //Now, draw the rotated/scaled image into the context
    bitmap.scaleBy(x: 1.0, y: -1.0)
    bitmap.draw(oldImage, in:  CGRect(origin: (x: -oldImage.size.width / 2,  y: -oldImage.size.height / 2, width:  oldImage.size.width, height: oldImage.size.height), size: oldImage.cgImage))

    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()

    return newImage

  }

below is the code i am not sure about

bitmap.draw(oldImage, in:  CGRect(origin: (x: -oldImage.size.width / 2,  y: -oldImage.size.height / 2, width:  oldImage.size.width, height: oldImage.size.height), size: oldImage.cgImage))

Ope

Manage the condition for image after capture from camera. And try this link: #9324630 It will help to sort out from the issue. – Bertolde

https://mcmap.net/q/92948/-ios-uiimagepickercontroller-result-image-orientation-after-upload – Asaph

When getting errors, never forget to tell people which ones they are! – Hairdresser

Answer 1

This is an extension of UIImage that targets Swift 4.0 and can rotate just the image without the need for a UIImageView. Tested successfully that the image was rotated, and not just had its exif data changed.

import UIKit

extension UIImage {
    func rotate(radians: CGFloat) -> UIImage {
        let rotatedSize = CGRect(origin: .zero, size: size)
            .applying(CGAffineTransform(rotationAngle: CGFloat(radians)))
            .integral.size
        UIGraphicsBeginImageContext(rotatedSize)
        if let context = UIGraphicsGetCurrentContext() {
            let origin = CGPoint(x: rotatedSize.width / 2.0,
                                 y: rotatedSize.height / 2.0)
            context.translateBy(x: origin.x, y: origin.y)
            context.rotate(by: radians)
            draw(in: CGRect(x: -origin.y, y: -origin.x,
                            width: size.width, height: size.height))
            let rotatedImage = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()

            return rotatedImage ?? self
        }

        return self
    }
}

To perform a 180 degree rotation, you can call it like this:

let rotatedImage = image.rotate(radians: .pi)

If for whatever reason it fails to rotate, the original image will then be returned.

Pedrick

This works, however the translation/origin seem to be wrong. The rotated image is shifted up and to the left :-/ – Tumbledown

@Tumbledown Can you post details on how you are calling it and some general details on the image? – Pedrick

CodeBender: I'm calling it with let rotatedImage = image.rotate(radians: .pi). The image is 1433 × 2099. I then found another solution which works perfectly: https://mcmap.net/q/270346/-rotating-uiimage-in-swift – Tumbledown

As @Tumbledown points out. The accepted solution has several translation issues, The solution that seems to work for everyone is posted in his comment. Here again for your convenience: https://mcmap.net/q/270346/-rotating-uiimage-in-swift – Cruel

Answer 2

set ImageView image

ImageView.transform = ImageView.transform.rotated(by: CGFloat(M_PI_2))

Swift 5

ImageView.transform = ImageView.transform.rotated(by: .pi)        // 180˚

ImageView.transform = ImageView.transform.rotated(by: .pi / 2)    // 90˚

ImageView.transform = ImageView.transform.rotated(by: .pi * 1.5)  // 270˚

Crosseye

Why M_PI_4? 90 degrees = M_PI_2 – Dubose

@JayeshMiruliya, also in Swift 3 you can use CGFloat.pi constant (divided by 2 ofc) – Farquhar

For Swift 4 Use: .pi/1 for 180˚ and .pi/2 for 90˚ – Twitch

To rotate UIImage you may check this GitHub link. Working for Swift3. You may use ".pi/1 for 180˚ and .pi/2 for 90˚" for radians param as per above comment. gist.github.com/norsez/e318d68f6a48786d35b3e7fd3b3a32ae – Pitsaw

For animation - UIView.animate(withDuration: 3) { self.needleImageView.transform = self.needleImageView.transform.rotated(by: CGFloat(Double.pi/2)) } – Genovera

perfect, easy, compact! – Gestate

Answer 3

In one line:

rotatedViewBox.transform = CGAffineTransform(rotationAngle: CGFloat.pi/2)

Pearly

This should be the best solution – Alti

Still the best solution in 2023 – Athenaathenaeum

Answer 4

 let angle =  CGFloat(M_PI_2)
  let tr = CGAffineTransform.identity.rotated(by: angle)
  ImageView.transform = tr

Illiterate

i want to rotate a UIImage not on imageview – Ope

Answer 5

In Swift 4.2 and Xcode 10.0

dropDownImageView.transform = dropDownImageView.transform.rotated(by: CGFloat(Double.pi / 2))

If you want to add animation...

UIView.animate(withDuration: 2.0, animations: {
   self.dropDownImageView.transform = self.dropDownImageView.transform.rotated(by: CGFloat(Double.pi / 2))
})

Originative

Answer 6

Rotate image via UIGraphics Context is comparatively heavy operation. The problems you may seen loosing quality and memory increase.

I suggest you should try to rotate the layer or view itself.

extension UIView {


    func rotate(degrees: CGFloat) {

        let degreesToRadians: (CGFloat) -> CGFloat = { (degrees: CGFloat) in
            return degrees / 180.0 * CGFloat.pi
        }
        self.transform =  CGAffineTransform(rotationAngle: degreesToRadians(degrees))

        // If you like to use layer you can uncomment the following line 
        //layer.transform = CATransform3DMakeRotation(degreesToRadians(degrees), 0.0, 0.0, 1.0)
    }
}

How to use

yourImageView.rotate(degrees: 40)

Unexceptional

Answer 7

You can use the code below for Swift 3:

extension UIImage {

func fixImageOrientation() -> UIImage? {
    var flip:Bool = false //used to see if the image is mirrored
    var isRotatedBy90:Bool = false // used to check whether aspect ratio is to be changed or not

    var transform = CGAffineTransform.identity

    //check current orientation of original image
    switch self.imageOrientation {
    case .down, .downMirrored:
        transform = transform.rotated(by: CGFloat(M_PI));

    case .left, .leftMirrored:
        transform = transform.rotated(by: CGFloat(M_PI_2));
        isRotatedBy90 = true
    case .right, .rightMirrored:
        transform = transform.rotated(by: CGFloat(-M_PI_2));
        isRotatedBy90 = true
    case .up, .upMirrored:
        break
    }

    switch self.imageOrientation {

    case .upMirrored, .downMirrored:
        transform = transform.translatedBy(x: self.size.width, y: 0)
        flip = true

    case .leftMirrored, .rightMirrored:
        transform = transform.translatedBy(x: self.size.height, y: 0)
        flip = true
    default:
        break;
    }

    // calculate the size of the rotated view's containing box for our drawing space
    let rotatedViewBox = UIView(frame: CGRect(origin: CGPoint(x:0, y:0), size: size))
    rotatedViewBox.transform = transform
    let rotatedSize = rotatedViewBox.frame.size

    // Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize)
    let bitmap = UIGraphicsGetCurrentContext()

    // Move the origin to the middle of the image so we will rotate and scale around the center.
    bitmap!.translateBy(x: rotatedSize.width / 2.0, y: rotatedSize.height / 2.0);

    // Now, draw the rotated/scaled image into the context
    var yFlip: CGFloat

    if(flip){
        yFlip = CGFloat(-1.0)
    } else {
        yFlip = CGFloat(1.0)
    }

    bitmap!.scaleBy(x: yFlip, y: -1.0)

    //check if we have to fix the aspect ratio
    if isRotatedBy90 {
        bitmap?.draw(self.cgImage!, in: CGRect(x: -size.width / 2, y: -size.height / 2, width: size.height,height: size.width))
    } else {
        bitmap?.draw(self.cgImage!, in: CGRect(x: -size.width / 2, y: -size.height / 2, width: size.width,height: size.height))
    }

    let fixedImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return fixedImage
}

Swage

Answer 8

Your code is not that far off from functional. You can apply the transform as you are doing directly to the bitmap, you don't need an intermediate view:

func imageRotatedByDegrees(oldImage: UIImage, deg degrees: CGFloat) -> UIImage {
    let size = oldImage.size

    UIGraphicsBeginImageContext(size)

    let bitmap: CGContext = UIGraphicsGetCurrentContext()!
    //Move the origin to the middle of the image so we will rotate and scale around the center.
    bitmap.translateBy(x: size.width / 2, y: size.height / 2)
    //Rotate the image context
    bitmap.rotate(by: (degrees * CGFloat(M_PI / 180)))
    //Now, draw the rotated/scaled image into the context
    bitmap.scaleBy(x: 1.0, y: -1.0)

    let origin = CGPoint(x: -size.width / 2, y: -size.width / 2)

    bitmap.draw(oldImage.cgImage!, in: CGRect(origin: origin, size: size))

    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return newImage
}

Also, if you're going to create a function that rotates an image, it is typically good form to include a clockwise: Bool parameter that will interpret the degrees argument as rotating clockwise or not. The implementation and appropriate conversion to radians I leave to you.

Also note that it's a bit hand-wavy on my part to assume that oldImage.size is non-zero. If it is, force-unwrapping UIGraphicsGetCurrentContext()! will probably crash. You should validate the oldImage's size and if it's invalid just return oldImage.

Viscid

While functional, this code will not rotate the image about the center unless in the unique scenario that the image is square. I used the intermediate method and it produced about-center rotation. – Demos

Answer 9

You can first set your image in imageView and rotate get your image in imageView

Here:

let customImageView = UIImageView()
customImageView.frame = CGRect.init(x: 0, y: 0, w: 250, h: 250)
customImageView.image = UIImage(named: "yourImage")

customImageView .transform = customImageView .transform.rotated(by: CGFloat.init(M_PI_2))
var rotatedImage = UIImage()
rotatedImage = customImageView.image!

Heroism

Answer 10

Your problem is that you use non-existing initializer for CGRect. If you want to use CGRect(origin:size:), then create origin properly, without width and height parameters. Or remove size parameter and use CGRect(x:y:width:height:).

Just replace this line

bitmap.draw(oldImage, in:  CGRect(origin: (x: -oldImage.size.width / 2,  y: -oldImage.size.height / 2, width:  oldImage.size.width, height: oldImage.size.height), size: oldImage.cgImage))

with this one:

let rect = CGRect(origin: CGPoint(x: -oldImage.size.width / 2,  y: -oldImage.size.height / 2), size: oldImage.size)
bitmap.draw(oldImage.cgImage!, in: rect)

Dubose

Answer 11

If you just don't want specific rotation and like to use all orientations one by one.

func rotateImage() -> UIImage {
    let newOrientation = Orientation(rawValue: self.imageOrientation.rawValue + 1) ?? UIImage.Orientation(rawValue: 0)
    return UIImage(cgImage: self.cgImage!, scale: self.scale, orientation: newOrientation!)
}

Hartz

Answer 12

UIGraphicsBeginImageContext(CGSize(width: bitmap.width, height: bitmap.height))
UIImage(cgImage: oldImage.cgImage, scale: 1, orientation: .leftMirrored).draw(at: .zero)
let image = UIGraphicsGetImageFromCurrentImageContext()!

Much shorter.

Bedstead

Answer 13

To start spinning a image view:

func startSpinning()  {
    UIView.animate(withDuration: 0.5, delay: 0, options: .repeat, animations: { () -> Void in
        self.gearImageView!.transform = self.gearImageView!.transform.rotated(by: .pi / 2)
    })
}

To stop spinning:

func stopSpinning()  {
    self.gearImageView.layer.removeAllAnimations()
}

Eluviation

Answer 14

Another working solution is to rotate the UIImage

1. Create an extension for UIImage

extension UIImage {
 
    /// Rotate the UIImage
    /// - Parameter orientation: Define the rotation orientation
    /// - Returns: Get the rotated image 
   func rotateImage(orientation: UIImage.Orientation) -> UIImage {
      guard let cgImage = self.cgImage else { return UIImage() }
      switch orientation {
           case .right:
               return UIImage(cgImage: cgImage, scale: 1.0, orientation: .up)
           case .down:
               return UIImage(cgImage: cgImage, scale: 1.0, orientation: .right)
           case .left:
               return UIImage(cgImage: cgImage, scale: 1.0, orientation: .down)
           default:
               return UIImage(cgImage: cgImage, scale: 1.0, orientation: .left)
       }
   }
}

2. Use it around your code

• Your UIImage

image.rotateImage(orientation: .up)

Privilege

cgImage property might return nil. You should change your return type to optional and return nil. Btw you should use the original image scale property to preserve its scale. – Milden

Answer 15

ImageView?.transform = transform.rotated(by: (CGFloat(Double.pi / 2)))

Swift 4.2

Rotation - right. Works fine.

Haaf