Caching Online Images Using AlamofireImage. It works on top of Alamofire in Swift.
Install AlamofireImage using cocoapods
pod 'AlamofireImage', '~> 3.1'
SetUp:
AlamofireImage and Alamofirelet imageCache = AutoPurgingImageCache( memoryCapacity: 111_111_111, preferredMemoryUsageAfterPurge: 90_000_000)Alamofire.request(self.nameUrl[i]).responseImage { response in
                    if response.result.value != nil {
                        let image = UIImage(data: response.data!, scale: 1.0)!
                        imageCache.add(image, withIdentifier: self.nameUrl[i])
                    }
    }
if let image = imageCache.image(withIdentifier: self.nameUrl[self.a])
        {
            self.localImageView.image = image
        }
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