This could be the worst solution but it works, You should set the frame of your image view first and then call this method.
-(void)adjustImageViewWithImageDimension:(CGRect)frame{
UIImageView *tempView = [[UIImageView alloc] initWithFrame:frame];
tempView.image = self.image;
tempView.contentMode = UIViewContentModeScaleAspectFill;
tempView.clipsToBounds = false;
CGFloat oldAlpha = self.alpha;
self.alpha = 1;
UIGraphicsBeginImageContext(tempView.bounds.size);
[tempView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self.alpha = oldAlpha;
self.image = resultingImage;
self.contentMode = UIViewContentModeTop;
self.clipsToBounds = YES;
}