Image Resize - Aspect Fit / Fill

image-resize.swift

public enum ImagePlacement {
    case fill
    case fit
}

public static func resize(_ image: UIImage, to size: CGSize, placement: ImagePlacement = .fill) -> UIImage {

    let frame: CGRect
    switch placement {
    case .fit:
        frame = CGRect(
            x: image.size.width / size.width > image.size.height / size.height ?
                0 : (size.width - image.size.width * (size.height / image.size.height)) / 2,
            y: image.size.width / size.width < image.size.height / size.height ?
                0 : (size.height - image.size.height * (size.width / image.size.width)) / 2,
            width: image.size.width / size.width > image.size.height / size.height ?
                size.width : image.size.width * (size.height / image.size.height),
            height: image.size.width / size.width < image.size.height / size.height ?
                size.height : image.size.height * (size.width / image.size.width)
        )
    case .fill:
        frame = CGRect(
            x: image.size.width / size.width < image.size.height / size.height ?
                0 : (size.width - image.size.width * (size.height / image.size.height)) / 2,
            y: image.size.width / size.width > image.size.height / size.height ?
                0 : (size.height - image.size.height * (size.width / image.size.width)) / 2,
            width: image.size.width / size.width < image.size.height / size.height ?
                size.width : image.size.width * (size.height / image.size.height),
            height: image.size.width / size.width > image.size.height / size.height ?
                size.height : image.size.height * (size.width / image.size.width)
        )
    }

    UIGraphicsBeginImageContext(size)
    image.draw(in: frame)
    let resized_image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return resized_image!
}

Thanks for sharing! 👍