iOS image cropping and resizing - ios

Question

I am using the library
linked here to resize a camera-captured image with the following code:
UIImage *image = [[UIImage alloc] initWithData:imageData];
CGFloat squareLength = SC_APP_SIZE.width;
CGFloat headHeight = _previewLayer.bounds.size.height - squareLength;//_previewLayer的frame是(0, 44, 320, 320 + 44)
CGSize size = CGSizeMake(squareLength * 2, squareLength * 2);
UIImage *scaledImage = [image resizedImageWithContentMode:UIViewContentModeScaleAspectFill bounds:size interpolationQuality:kCGInterpolationHigh];
CGRect cropFrame = CGRectMake((scaledImage.size.width - size.width) / 2, (scaledImage.size.height - size.height) / 2 + headHeight, size.width, size.height);
UIImage *croppedImage = [scaledImage croppedImage:cropFrame];
UIDeviceOrientation orientation = [UIDevice currentDevice].orientation;
if (orientation != UIDeviceOrientationPortrait) {
CGFloat degree = 0;
if (orientation == UIDeviceOrientationPortraitUpsideDown) {
degree = 180;// M_PI;
} else if (orientation == UIDeviceOrientationLandscapeLeft) {
degree = -90;// -M_PI_2;
} else if (orientation == UIDeviceOrientationLandscapeRight) {
degree = 90;// M_PI_2;
}
croppedImage = [croppedImage rotatedByDegrees:degree];
}
The code works no matter what orientation, back camera or front camera, when the image is captured through the camera.
Problem happens when I use the same code (except getting the image's exif orientation instead of the device orientation) for an image that was originally camera-captured, but accessed through iOS camera roll.
Case: when the image saved in the camera roll was captured in landscape orientation by the BACK camera. Effectively, the image gets an exif orientation that indicates it was captured in portrait mode...but it's still a widescreen image.
The code crops the image disproportionately, leaving a black bar of empty space on the edge. I can't figure out what the problem is. Can someone point me in the right direction?