How to rotate UIImage

Question

I\'m developing an iOS app for iPad. Is there any way to rotate a UIImage 90º and then add it to a UIImageView? I\'ve tried a lot of different codes but none worked...

Answer 1

This is what i've done when i wanted to change the orientation of an image (rotate 90 degree clockwise).

//Checking for the orientation ie, image taken from camera is in portrait or not.
if(yourImage.imageOrientation==3)
{
    //Image is in portrait mode.
    yourImage=[self imageToRotate:yourImage RotatedByDegrees:90.0];
}

- (UIImage *)image:(UIImage *)imageToRotate RotatedByDegrees:(CGFloat)degrees
{
    CGFloat radians = degrees * (M_PI / 180.0);

    UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0, image.size.height, image.size.width)];
    CGAffineTransform t = CGAffineTransformMakeRotation(radians);
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;

    UIGraphicsBeginImageContextWithOptions(rotatedSize, NO, [[UIScreen mainScreen] scale]);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();

    CGContextTranslateCTM(bitmap, rotatedSize.height / 2, rotatedSize.width / 2);

    CGContextRotateCTM(bitmap, radians);

    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-image.size.width / 2, -image.size.height / 2 , image.size.height, image.size.width), image.CGImage );
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

The rotated image may be of size >= 15MB (from my experience). So you should compress it and use it. Otherwise, you may met with crash causing memory pressure. Code I used for compressing is given below.

NSData *imageData = UIImageJPEGRepresentation(yourImage, 1);
//1 - it represents the quality of the image.
NSLog(@"Size of Image(bytes):%d",[imageData length]);
//Here I used a loop because my requirement was, the image size should be <= 4MB.
//So put an iteration for more than 1 time upto when the image size is gets <= 4MB.
for(int loop=0;loop<100;loop++)
{
    if([imageData length]>=4194304)  //4194304 = 4MB in bytes.
    {
        imageData=UIImageJPEGRepresentation(yourImage, 0.3);
        yourImage=[[UIImage alloc]initWithData:imageData];
    }
    else
    {
        NSLog(@"%d time(s) compressed.",loop);
        break;
    }
}

Now your yourImage can be used for anywhere.. Happy coding...