Weird behavior when rotating AVFoundation stills on iOS - iphone

Question

OK, so the following code works, but I don't get why. I am capturing still images from the Front camera using AVFoundation. I have this code before initiating capture:
if ([connection isVideoOrientationSupported]) {
AVCaptureVideoOrientation orientation;
switch ([UIDevice currentDevice].orientation) {
case UIDeviceOrientationPortraitUpsideDown:
orientation = AVCaptureVideoOrientationPortraitUpsideDown;
break;
case UIDeviceOrientationLandscapeLeft:
orientation = AVCaptureVideoOrientationLandscapeRight;
break;
case UIDeviceOrientationLandscapeRight:
orientation = AVCaptureVideoOrientationLandscapeLeft;
break;
default:
orientation = AVCaptureVideoOrientationPortrait;
break;
}
[connection setVideoOrientation:orientation];
}
and then this in the captureStillImageAsynchronouslyFromConnection:completionHandler: to store the image:
NSData *imageData = [AVCaptureStillImageOutputjpegStillImageNSDataRepresentation:imageSampleBuffer];
UIImage *i = [UIImage imageWithData:imageData];
orientation:i.imageOrientation];
UIGraphicsBeginImageContext(i.size);
[i drawAtPoint:CGPointMake(0.0, 0.0)];
image.image = UIGraphicsGetImageFromCurrentImageContext();
as you can see, I don't rotate the image or anything, just draw it in the context and save. But as soon as I try to use i it is always rotated by 90 degrees. If I try to rotate it using
UIImage *rotated = [[UIImage alloc] initWithCGImage:i.CGImage scale:1.0f orientation:i.imageOrientation];
it doesn't work (no change from just using i).
I understand that UIImage might just draw the image into the context using the right orientation automatically, but WTF?

Answer 1

you can check the device orientation like this :
if ((deviceOrientation == UIInterfaceOrientationLandscapeLeft && position == AVCaptureDevicePositionBack)
)
{
and if above condition or whatever your condition is satisfies then you can rotate your image using the code below :
-(void)rotateImageByDegress:(int)degrees{
if (degrees == 0.0) {
return self;
}
// 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;
[rotatedViewBox release];
// 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;
}