UIImage Resize Extension

Question

I made an extension that lets me resize a UIImage but I'm wondering if I'm calling it correctly. The extension is in it's own file and is like this:

extension UIImage {
    func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
        let size = image.size

        let widthRatio  = targetSize.width  / image.size.width
        let heightRatio = targetSize.height / image.size.height

        // Figure out what our orientation is, and use that to form the rectangle
        var newSize: CGSize
        if(widthRatio > heightRatio) {
            newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
        } else {
            newSize = CGSize(width: size.width * widthRatio,  height: size.height * widthRatio)
        }

        // This is the rect that we've calculated out and this is what is actually used below
        let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)

        // Actually do the resizing to the rect using the ImageContext stuff
        UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
        image.draw(in: rect)
        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage!
    }
}

I then call it like this:

img.resizeImage(image: img, targetSize: CGSize(width: 200.0, height: 200.0))

where img is a UIImage. However, it seems weird to me that I'm calling a function on a UIImage, but also passing it in as an argument. Is this the correct way to do it or is there a more concise way?

score 3 · Accepted Answer · answered Jan 15 '17 at 00:57

3

You are losing the convenience of using extensions. Check here: https://www.hackingwithswift.com/read/24/2/creating-a-swift-extension

The main idea is that you need to remove that first argument and use self inside the function code

answered Jan 15 '17 at 00:57

eried

398
5
15

UIImage Resize Extension

1 Answers1