Why image stretch(UIImage to CIImage to UIImage) - ios

Question

Due to some reasons, I need to transform an image from UIImage to CIImage(for processing) and to UIImage back again. I do it by UIImage-CGImage-CIImage-UIImage.Ignoring the irrelevant code, the code is showing behind.
UIImage *originalPic = [[UIImage alloc]init];//get this from UIImagePickerController
CIImage *originalCIPic = [[CIImage alloc]init];
originalCIPic = [CIImage imageWithCGImage:originalPic.CGImage];
UIImage *finalResultUIImage = [UIImage imageWithCIImage:originalCIPic];
//then I put the image on an Image View(contentMode has been set)
self.viewOfImage.contentMode = UIViewContentModeScaleAspectFit;
self.viewOfImage.image=finalResultUIImage;
//I used NSLog to check the size, but they are the same.(before transforming and after)
NSLog(#"this is the final UIImage,size is %# ",NSStringFromCGSize(finalResultUIImage.size));
But the image showing on the screen is stretched.
What's wrong with me? Or Is there any alternative choice for me?
Thank you very much andI am so sorry I have not enough reputation to post picture.
:)

Answer 1

Try this:
NSString *filePath = [[NSBundle mainBundle] pathForResource:#"abcd" ofType:#"png"];
CIImage *ciImage = [CIImage imageWithContentsOfURL:[NSURL fileURLWithPath:filePath]];
UIImage *imageByCIImage = [UIImage imageWithCIImage:ciImage scale:1.0f orientation:UIImageOrientationUp];
UIGraphicsBeginImageContext(imageByCIImage.size);
[imageByCIImage drawInRect:CGRectMake(0,0,imageByCIImage.size.width,imageByCIImage.size.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
self.imageview.image = newImage;
UIGraphicsEndImageContext();