Objective-c – iPhone camera pics come up rotated — CGAffineTransformInvert: singular matrix

The problem was that image rotation was added to the photo as EXIF data not used by most browsers. There are two solutions:

1. Apply the rotation on the server side. I was using the Ruby plugin Paperclip (by Thoughtbot) and just had to include the auto-orient convert option to the has_attached_file command in the model:

   has_attached_file :photo, :convert_options => { :all => '-auto-orient' }

2. Rotate the photo within the iPhone app. This was solved in another stackoverflow question; calling the scaleAndRotate method replaces the rotation meta-data with an image transform, thanks to @Squeegy.

It is because the imageOrientation isn't taken into account.

There is a similar question (Resizing UIimages pulled from the Camera also ROTATES the UIimage?) and I've modified the code a bit to work with cropping image.

Here you are:

static inline double radians (double degrees) {return degrees * M_PI/180;}

+(UIImage*)cropImage:(UIImage*)originalImage toRect:(CGRect)rect{

    CGImageRef imageRef = CGImageCreateWithImageInRect([originalImage CGImage], rect);

    CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
    CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);
    CGContextRef bitmap = CGBitmapContextCreate(NULL, rect.size.width, rect.size.height, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    if (originalImage.imageOrientation == UIImageOrientationLeft) {
        CGContextRotateCTM (bitmap, radians(90));
        CGContextTranslateCTM (bitmap, 0, -rect.size.height);

    } else if (originalImage.imageOrientation == UIImageOrientationRight) {
        CGContextRotateCTM (bitmap, radians(-90));
        CGContextTranslateCTM (bitmap, -rect.size.width, 0);

    } else if (originalImage.imageOrientation == UIImageOrientationUp) {
        // NOTHING
    } else if (originalImage.imageOrientation == UIImageOrientationDown) {
        CGContextTranslateCTM (bitmap, rect.size.width, rect.size.height);
        CGContextRotateCTM (bitmap, radians(-180.));
    }

    CGContextDrawImage(bitmap, CGRectMake(0, 0, rect.size.width, rect.size.height), imageRef);
    CGImageRef ref = CGBitmapContextCreateImage(bitmap);

    UIImage *resultImage=[UIImage imageWithCGImage:ref];
    CGImageRelease(imageRef);
    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return resultImage;
}