iOS App memory optimization - image downsampling technique

imageDownsampling

// Image downsampling technique provides smaller image buffer allocations which leads to memory optimization

extension UIImageView {
    func downsampleImage(from imageUrl: URL) -> UIImage {
        let imageSourceOptions = [kCGImageSourceShouldCache: false] as CFDictionary
        guard let imageSource = CGImageSourceCreateWithURL(imageUrl as CFURL, imageSourceOptions) else { return UIImage() }
        let maxDimensionInPixels = max(self.bounds.size.width, self.bounds.size.height) * self.traitCollection.displayScale
        let downsampleOptions =
            [kCGImageSourceCreateThumbnailFromImageAlways: true,
             kCGImageSourceShouldCacheImmediately: true,
             kCGImageSourceCreateThumbnailWithTransform: true,
             kCGImageSourceThumbnailMaxPixelSize: maxDimensionInPixels] as CFDictionary
        guard let downsampledImage =
            CGImageSourceCreateThumbnailAtIndex(imageSource, 0, downsampleOptions) else { return UIImage() }
        return UIImage(cgImage: downsampledImage)
    }
}

//example usage
imageView.image = imageView.downsampleImage(from: imgUrl)

Before and after results, the same image url