How to easily resize/optimize an image size with iOS?

Question

My application is downloading a set of image files from the network, and saving them to the local iPhone disk. Some of those images are pretty big in size (widths larger tha

Answer 1

For Swift 3, the below code scales the image keeping the aspect ratio. You can read more about the ImageContext in Apple's documentation:

extension UIImage {
    class func resizeImage(image: UIImage, newHeight: CGFloat) -> UIImage {
        let scale = newHeight / image.size.height
        let newWidth = image.size.width * scale
        UIGraphicsBeginImageContext(CGSize(width: newWidth, height: newHeight))
        image.draw(in: CGRect(x: 0, y: 0, width: newWidth, height: newHeight))
        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return newImage!
    }
}

To use it, call resizeImage() method:

UIImage.resizeImage(image: yourImageName, newHeight: yourImageNewHeight)