iOS - Context to Image

通过画布生成图片

func createImage(size: CGSize) -> UIImage? {
    UIGraphicsBeginImageContextWithOptions(size, false, UIScreen.main.scale)
    guard let context = UIGraphicsGetCurrentContext() else { return nil }
    draw(context: context, size: size)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image
}