SDWebImage

https://github.com/rs/SDWebImage

Step :1
Install pod 'SDWebImage', '~>3.8'

Step:2

import SDWebImage

 let url = NSURL(string: userdetail.valueForKey("profile") as! String)
        let placeHolderImage = UIImage.gifWithName("loading165-92")
        profileimg.sd_setImageWithURL(url, placeholderImage:placeHolderImage, completed: { (image, error, cacheType, url) -> Void in
            if (cacheType == SDImageCacheType.None && image != nil) {
                self.profileimg.alpha = 0;
                UIView.animateWithDuration(0.0, animations: { () -> Void in
                    self.profileimg.alpha = 1
                })
            } else {
                self.profileimg.alpha = 1;
            }
        })
     profileimg.layer.cornerRadius=profileimg.frame.size.width/2
      profileimg.clipsToBounds=true
***************************************

let SUBcat_image = UIImageView()

SUBcat_image.isUserInteractionEnabled=true

SUBcat_image.frame=CGRect(x: 5,y: 0,width: WidthofIMG,height: WidthofIMG)

let url = NSURL(string: (self.searcharr.object(at: subcat) as AnyObject).value(forKey: "subcat_image") as! String)

let placeHolderImage = UIImage.sd_animatedGIFNamed("100X100")

 SUBcat_image.sd_setImage(with: url as URL!, placeholderImage:placeHolderImage, completed: { (image, error, cacheType, url) -> Void in

  if (cacheType == SDImageCacheType.none && image != nil) {

         SUBcat_image.alpha = 0;

   UIView.animate(withDuration: 0.0, animations: { () -> Void in

         SUBcat_image.alpha = 1

          })

    } else {

           SUBcat_image.alpha = 1;

            }

       })

 Sub_cointain_View.addSubview(SUBcat_image)

****https://stackoverflow.com/questions/38949214/ambiguous-use-of-sd-setimagewithplaceholderimagecompleted-with-swift-3****