Resize UIImage to 200x200pt/px

Question

I have been struggling resizing an image. Basically I have stumpled upon: How to scale down a UIImage and make it crispy / sharp at the same time instead of blurry?

Answer 1

This code uses UIGraphicsImageRenderer introduced in iOS 10: in my testing it was 10-40% faster than earlier samples with UIGraphicsBeginImageContext (Swift 4 / Xcode 9):

extension UIImage {
        func renderResizedImage (newWidth: CGFloat) -> UIImage {
            let scale = newWidth / self.size.width
            let newHeight = self.size.height * scale
            let newSize = CGSize(width: newWidth, height: newHeight)

            let renderer = UIGraphicsImageRenderer(size: newSize)

            let image = renderer.image { (context) in
                self.draw(in: CGRect(origin: CGPoint(x: 0, y: 0), size: newSize))
            }
            return image
        }
    }