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 the image appears well on screen , however if the image was taken in landscape mode the image appears streched on the screen(as it tries to appear on portrait mode!). I dont know how to fix this but i guess one solution is first to check if the image is in portrait/landscape mode and then if it is on landscape mode rotate it by 90degrees before showing it on screen. So how could i do that?

Answer 1

self.imageview.transform = CGAffineTransformMakeRotation(M_PI_2);

Swift 4+:

self.imageview.transform = CGAffineTransform(rotationAngle: CGFloat(Double.pi/2))

Answer 2

This is the complete code for rotation of image to any degree just add it to appropriate file ie in .m as below where you want to use the image processing

for .m

@interface UIImage (RotationMethods)
- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees;
@end

@implementation UIImage (RotationMethods)

static CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;};

- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees 
{   
    // calculate the size of the rotated view's containing box for our drawing space
    UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.size.width, self.size.height)];
    CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;

    // Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize);
    CGContextRef bitmap = 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, DegreesToRadians(degrees));

    // Now, draw the rotated/scaled image into the context
    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]);

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

}

@end

This is the code snippet form apple's SquareCam example.

To call the above method just use the below code

UIImage *rotatedSquareImage = [square imageRotatedByDegrees:rotationDegrees];

Here the square is one UIImage and rotationDegrees is one flote ivar to rotate the image that degrees

Answer 3

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)

Answer 4

- (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 5

Simply add this code to the image.

Image.transform=CGAffineTransformMakeRotation(M_PI / 2);

Answer 6

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/2)

Answer 7

Swift 3 version:

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

Answer 8

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 9

Swift 4 | Xcode 9 syntax (please note that this code rotates a UIImageView 90 degrees clockwise, not a UIImage):

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

Answer 10

 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(Double.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

}

Use of function

imageRotatedByDegrees(oldImage: yourImage, deg: degree) 

Answer 11

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

    }
}