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

Answer 1

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:

Answer 2

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
        }
    }

Answer 3

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)

Answer 4

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
    }
}

Answer 5

@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
}

Answer 6

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
}