How to merge two UIImages?

Question

I am trying to merge two different images and create a new one. This is the way I would like to do: I have this image (A):

It\'s a PNG image and I would like to mer

Answer 1

Slightly modified version of answer by budidino. This implementation also handles negative posX and posY correctly.

extension UIImage {
    func overlayWith(image: UIImage, posX: CGFloat, posY: CGFloat) -> UIImage {
        let newWidth = posX < 0 ? abs(posX) + max(self.size.width, image.size.width) :
            size.width < posX + image.size.width ? posX + image.size.width : size.width
        let newHeight = posY < 0 ? abs(posY) + max(size.height, image.size.height) :
            size.height < posY + image.size.height ? posY + image.size.height : size.height
        let newSize = CGSize(width: newWidth, height: newHeight)

        UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0)
        let originalPoint = CGPoint(x: posX < 0 ? abs(posX) : 0, y: posY < 0 ? abs(posY) : 0)
        self.draw(in: CGRect(origin: originalPoint, size: self.size))
        let overLayPoint = CGPoint(x: posX < 0 ? 0 : posX, y: posY < 0 ? 0 : posY)
        image.draw(in: CGRect(origin: overLayPoint, size: image.size))
        let newImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()

        return newImage
    }
}