How to rotate an image 90 degrees on iOS?

Question

What I want to do is take a snapshot from my camera , send it to a server and then the server sends me back the image on a viewController. If the image is in portrait mode t

Answer 1

- (UIImage *)rotateImage:(UIImage*)image byDegree:(CGFloat)degrees 
{   
    UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,image.size.width, image.size.height)];
    CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;
    [rotatedViewBox release];

    UIGraphicsBeginImageContext(rotatedSize);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();


    CGContextTranslateCTM(bitmap, rotatedSize.width, rotatedSize.height);

    CGContextRotateCTM(bitmap, DegreesToRadians(degrees));


    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-image.size.width, -image.size.height, image.size.width, image.size.height), [image CGImage]);

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;

}

Answer 2

Swift 4+.

arrowImageView.transform = CGAffineTransform(rotationAngle: .pi/2)

Note: angle is in radian

.pi = 180 degree

.pi/2 = 90 degree

If you want to add with animation

  @IBAction func applyTransForm(sender: UIButton) {
        sender.isSelected = !sender.isSelected
        UIView.animate(withDuration: 1, animations: {
        if sender.isSelected {
            self.arrowImageView.transform = CGAffineTransform(rotationAngle: .pi)
        } else {
            self.arrowImageView.transform = CGAffineTransform(rotationAngle: 0)

        }
        })
    }

Output:

Answer 3

Doing it in the Image Level, in Swift 5:

extension UIImage{
    
    
    func imageRotated(by radian: CGFloat) -> UIImage{
        
        let rotatedSize = CGRect(origin: .zero, size: size)
            .applying(CGAffineTransform(rotationAngle: radian))
            .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: radian)
            draw(in: CGRect(x: -origin.y, y: -origin.x,
                            width: size.width, height: size.height))
            let rotatedImage = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()

            return rotatedImage ?? self
        }

        return self

    }
}

Answer 4

Swift 3 version:

imageView.transform = CGAffineTransform(rotationAngle: CGFloat(M_PI_2))

Answer 5

I got an error trying this in XCode 6.3 Swift 1.2

self.imageview.transform = CGAffineTransformMakeRotation(M_PI_2);

You should try this to force type cast fix:

self.imageview.transform = CGAffineTransformMakeRotation(CGFloat(M_PI_2));

Swift 4 Edit

imageview.transform = CGAffineTransform(rotationAngle: .pi)

Answer 6

Swift 3 and Swift 4 use .pi instead

eg:

//rotate 90 degrees
myImageView.transform = CGAffineTransform(rotationAngle: .pi / 2)

//rotate 180 degrees
myImageView.transform = CGAffineTransform(rotationAngle: .pi)

//rotate 270 degrees
myImageView.transform = CGAffineTransform(rotationAngle: .pi * 1.5)