Rotate UIImage in swift

Question

I want to rotate UIImage in clockwise direction. But my current code do not perform function accurate some time it rotate and some time its skip rotation. I want my UIImage will continuously rotate clockwise on my action button. Here is my current code:

imageView.image = imageView.image!.imageRotatedByDegrees(angle, flip: false)
angle = angle + 90
if angle > 360{
    angle = 0
}

Need to use imageView.transform = CGAffineTransformMakeRotation(CGFloat(90) * CGFloat(M_PI) / 180.0) — Sean Lintern, Apr 15 '16 at 10:50
The simplest method in swift 4 to make a rotated image: [http://stackoverflow.com/a/53491799/341994](http://stackoverflow.com/a/53491799/341994) — xuzepei, Nov 27 '18 at 04:06

score 25 · Accepted Answer · edited Apr 17 '17 at 00:00

This works for me:

works Fine :)

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: CGRectMake(0, 0, oldImage.size.width, oldImage.size.height))
    let t: CGAffineTransform = CGAffineTransformMakeRotation(degrees * CGFloat(M_PI / 180))
    rotatedViewBox.transform = t
    let rotatedSize: CGSize = rotatedViewBox.frame.size
    //Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize)
    let bitmap: CGContextRef = UIGraphicsGetCurrentContext()!
    //Move the origin to the middle of the image so we will rotate and scale around the center.
    CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2)
    //Rotate the image context
    CGContextRotateCTM(bitmap, (degrees * CGFloat(M_PI / 180)))
    //Now, draw the rotated/scaled image into the context
    CGContextScaleCTM(bitmap, 1.0, -1.0)
    CGContextDrawImage(bitmap, CGRectMake(-oldImage.size.width / 2, -oldImage.size.height / 2, oldImage.size.width, oldImage.size.height), oldImage.CGImage)
    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return newImage
}

Swift 3:

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.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.pi / 180))
    //Now, draw the rotated/scaled image into the context
    bitmap.scaleBy(x: 1.0, y: -1.0)
    bitmap.draw(oldImage.cgImage!, in: CGRect(x: -oldImage.size.width / 2, y: -oldImage.size.height / 2, width: oldImage.size.width, height: oldImage.size.height))
    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return newImage
}

gleb · Answer 2 · 2017-05-24T08:02:24.413

extension UIImage {
    public func imageRotatedByDegrees(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: self.size.width, height: self.size.height))
        let t: CGAffineTransform = CGAffineTransform(rotationAngle: degrees * CGFloat.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.pi / 180))
        //Now, draw the rotated/scaled image into the context
        bitmap.scaleBy(x: 1.0, y: -1.0)
        bitmap.draw(self.cgImage!, in: CGRect(x: -self.size.width / 2, y: -self.size.height / 2, width: self.size.width, height: self.size.height))
        let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return newImage
    }


    public func fixedOrientation() -> UIImage {
        if imageOrientation == UIImageOrientation.up {
            return self
        }

        var transform: CGAffineTransform = CGAffineTransform.identity

        switch imageOrientation {
        case UIImageOrientation.down, UIImageOrientation.downMirrored:
            transform = transform.translatedBy(x: size.width, y: size.height)
            transform = transform.rotated(by: CGFloat.pi)
            break
        case UIImageOrientation.left, UIImageOrientation.leftMirrored:
            transform = transform.translatedBy(x: size.width, y: 0)
            transform = transform.rotated(by: CGFloat.pi/2)
            break
        case UIImageOrientation.right, UIImageOrientation.rightMirrored:
            transform = transform.translatedBy(x: 0, y: size.height)
            transform = transform.rotated(by: -CGFloat.pi/2)
            break
        case UIImageOrientation.up, UIImageOrientation.upMirrored:
            break
        }

        switch imageOrientation {
        case UIImageOrientation.upMirrored, UIImageOrientation.downMirrored:
            transform.translatedBy(x: size.width, y: 0)
            transform.scaledBy(x: -1, y: 1)
            break
        case UIImageOrientation.leftMirrored, UIImageOrientation.rightMirrored:
            transform.translatedBy(x: size.height, y: 0)
            transform.scaledBy(x: -1, y: 1)
        case UIImageOrientation.up, UIImageOrientation.down, UIImageOrientation.left, UIImageOrientation.right:
            break
        }

        let ctx: CGContext = CGContext(data: nil,
                                       width: Int(size.width),
                                       height: Int(size.height),
                                       bitsPerComponent: self.cgImage!.bitsPerComponent,
                                       bytesPerRow: 0,
                                       space: self.cgImage!.colorSpace!,
                                       bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)!

        ctx.concatenate(transform)

        switch imageOrientation {
        case UIImageOrientation.left, UIImageOrientation.leftMirrored, UIImageOrientation.right, UIImageOrientation.rightMirrored:
            ctx.draw(self.cgImage!, in: CGRect(x: 0, y: 0, width: size.height, height: size.width))
        default:
            ctx.draw(self.cgImage!, in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
            break
        }

        let cgImage: CGImage = ctx.makeImage()!

        return UIImage(cgImage: cgImage)
    }
}

@Jason, You should fix orientation of image before rotation.

let image = oldimage.fixedOrientation().imageRotatedByDegrees(90.0)

awesome! only solution that works out of the box! thanks! :) — dy_, May 25 '17 at 18:12
Great solution. Thank you very much. I tried lots of solutions on SO, but this is the only one that really works. — Timo, Dec 06 '17 at 15:37
Size calculation is not necessary there. We simply do it with reverse. Because if you do it on 1149 x 356 then you will get image sized 357 x 1149 with this function. — Almas Dusal, May 10 '19 at 03:00

score 8 · Answer 3 · edited Nov 25 '16 at 12:11

@Jason Chitla, I cant comment yet, so Im posting it as a new answer. The above solution from @Albert works, but only for square images. The problem is, that

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

is still using the original size, so if you rotate it 90 degrees, aspect is wrong.

What works for me is to use the new rotatedSize, like this:

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(self.cgImage!, in: CGRect(x: -rotatedSize.width / 2, y: -rotatedSize.height / 2, width: rotatedSize.width, height: rotatedSize.height))
    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return newImage
}

score 7 · Answer 4 · answered Apr 15 '16 at 11:01

You can create a function like this to make your image rotate in clockwise forever:

override func viewDidLoad() {
        super.viewDidLoad()

        let kRotationAnimationKey = "com.myapplication.rotationanimationkey"

        func rotateView(view: UIView, duration: Double = 1) {
            if view.layer.animationForKey(kRotationAnimationKey) == nil {
                let rotationAnimation = CABasicAnimation(keyPath: "transform.rotation")

                rotationAnimation.fromValue = 0.0
                rotationAnimation.toValue = Float(M_PI * 2.0)
                rotationAnimation.duration = duration
                rotationAnimation.repeatCount = Float.infinity

                view.layer.addAnimation(rotationAnimation, forKey: kRotationAnimationKey)
            }
        }
      rotateView(self.imageView)
}

Result is:

You are rotating UIView not UIImage, this is making big difference, if you are working with photo app and need to save result. — Roman Safin, Sep 16 '16 at 10:46

score 3 · Answer 5 · answered Nov 02 '16 at 10:34

For those who need the code from @Mughees in Swift 3:

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.cgImage!, in: CGRect(x: -oldImage.size.width / 2, y: -oldImage.size.height / 2, width: oldImage.size.width, height: oldImage.size.height))
    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return newImage
}

this code rotates the image fine, but the aspect ratio is now reversed... the old image's height is now the width and vice versa. Does anyone know how to fix this? I think its because the rotatedSize is incorrect, but when I try to flip that, the new image is just smaller. — Jason Chitla, Nov 06 '16 at 03:10

Almas Dusal · Answer 6 · 2019-05-10T03:46:35.367

I fixed first function of @gleb's answer little bit. Size calculation is not necessary there. We simply should do it with reverse. Because if you do it size of 1149 x 356 with @gleb's function then you will get image sized 357 x 1149.

    extension UIImage {

        public func imageRotatedByDegrees(degrees: CGFloat) -> UIImage {
            let rotatedSize: CGSize = CGRect(x: 0, y: 0, width: self.size.height, height: self.size.width).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.pi / 180))
            //Now, draw the rotated/scaled image into the context
            bitmap.scaleBy(x: 1.0, y: -1.0)
            bitmap.draw(self.cgImage!, in: CGRect(x: -self.size.width / 2, y: -self.size.height / 2, width: self.size.width, height: self.size.height))

            let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!

            UIGraphicsEndImageContext()
            return newImage
        }
    }

Michael · Answer 7 · 2020-09-19T11:13:57.637

This s probably easier and it is Swift 5 syntax:

// MARK: Rotate
extension UIImage {
    func rotate(radians: Float) -> UIImage? {
        var newSize = CGRect(origin: CGPoint.zero, size: self.size).applying(CGAffineTransform(rotationAngle: CGFloat(radians))).size
        // Trim off the extremely small float value to prevent core graphics from rounding it up
        newSize.width = floor(newSize.width)
        newSize.height = floor(newSize.height)

        UIGraphicsBeginImageContextWithOptions(newSize, false, self.scale)
        let context = UIGraphicsGetCurrentContext()!

        // Move origin to middle
        context.translateBy(x: newSize.width/2, y: newSize.height/2)
        // Rotate around middle
        context.rotate(by: CGFloat(radians))
        // Draw the image at its center
        self.draw(in: CGRect(x: -self.size.width/2, y: -self.size.height/2, width: self.size.width, height: self.size.height))

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage
    }
}

This is the only solution that worked for me without altering the resolution, or scale of the images in my UISegementedControl — Jav Solo, Sep 06 '21 at 17:02

score 0 · Answer 8 · answered Nov 15 '19 at 13:11

I believe it's worth to post solution using CoreImage. It's just couple of lines and it works great for me.

Please note: when getting final UIImage, it's necessary to convert to CGImage first to respect extent of CIImage

extension UIImage {
    func imageRotated(by degrees: CGFloat) -> UIImage {

        let orientation = CGImagePropertyOrientation(imageOrientation)
        // Create CIImage respecting image's orientation 
        guard let inputImage = CIImage(image: self)?.oriented(orientation) 
            else { return self }

        // Rotate the image itself
        let rotation = CGAffineTransform(rotationAngle: (degrees * CGFloat.pi / 180))
        let outputImage = inputImage.transformed(by: rotation)

        // Create CGImage first
        guard let cgImage = CIContext().createCGImage(outputImage, from: outputImage.extent) 
            else { return self }

        // Create output UIImage from CGImage
        return UIImage(cgImage: cgImage)
    }
}

Rotate UIImage in swift

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