How to get the displayed image frame from UIImageView?

If it's UIViewContentModeScaleAspectFit, it's something like this:

UIImageView *iv; // your image view
CGSize imageSize = iv.image.size;
CGFloat imageScale = fminf(CGRectGetWidth(iv.bounds)/imageSize.width, CGRectGetHeight(iv.bounds)/imageSize.height);
CGSize scaledImageSize = CGSizeMake(imageSize.width*imageScale, imageSize.height*imageScale);
CGRect imageFrame = CGRectMake(roundf(0.5f*(CGRectGetWidth(iv.bounds)-scaledImageSize.width)), roundf(0.5f*(CGRectGetHeight(iv.bounds)-scaledImageSize.height)), roundf(scaledImageSize.width), roundf(scaledImageSize.height));

Use this api from AVFoundation

#import <AVFoundation/AVFoundation.h>

CGRect imageRect = 
    AVMakeRectWithAspectRatioInsideRect(imageView.image.size, imageView.bounds);

In fact, it's built-in since iOS 4 (for UIViewContentModeScaleAspectFit):

@import AVFoundation;

AVMakeRectWithAspectRatioInsideRect(imageView.image.size, imageView.bounds);

Since frame components may be not round numbers, consider wrapping the call by

CGRectIntegral(…)

See http://nshipster.com/image-resizing/ for more tricks.