iOS 通过String生成二维码图片（swift）

自动生成二维码图片

extension String {
    public func createQRImage(size: CGFloat) -> UIImage? {
        let strData = self.data(using: .utf8, allowLossyConversion: false)
        // 创建一个二维码的滤镜
        guard let qrFilter = CIFilter(name: "CIQRCodeGenerator") else { return nil }
        qrFilter.setValue(strData, forKey: "inputMessage")
        qrFilter.setValue(size <= 150 ? "L" : "H", forKey: "inputCorrectionLevel")
        let qrCIImage = qrFilter.outputImage
        // 创建一个颜色滤镜,黑白色
        guard let colorFilter = CIFilter(name: "CIFalseColor") else { return nil }
        colorFilter.setDefaults()
        colorFilter.setValue(qrCIImage, forKey: "inputImage")
        colorFilter.setValue(CIColor.black, forKey: "inputColor0")
        colorFilter.setValue(CIColor.white, forKey: "inputColor1")
        
        guard let outputImage = colorFilter.outputImage else { return nil }
        let scale = size / outputImage.extent.size.width
        let image_tr = outputImage.transformed(by: CGAffineTransform(scaleX: scale, y: scale))
        let qrImage = UIImage(ciImage: image_tr)
        return qrImage
    }
}