Ios swift生成背景透明的二维码

在我的swift 2应用程序中，我可以生成如下二维码：

let data = "1234567890".dataUsingEncoding(NSISOLatin1StringEncoding, allowLossyConversion: false)
let filter = CIFilter(name: "CIQRCodeGenerator")
filter!.setValue(data, forKey: "inputMessage")
filter!.setValue("Q", forKey: "inputCorrectionLevel")
qrcodeImage = filter!.outputImage
let transformedImage = qrcodeImage.imageByApplyingTransform(CGAffineTransformMakeScale(150, 150))
QRCodeImage.image = UIImage(CIImage: transformedImage)

QRCodeImage.backgroundColor = UIColor.clearColor()

QRCodeImage.backgroundcolor = UIColor(white: 1, alpha: 0.5)

let myChosenColor = UIColor(red:0.93, green:0.31, blue:0.23, alpha:1.00)
let qrURLImage = URL(string: "https://stackoverflow.com")?.qrImage(using: myChosenColor)
myQrImageView.image = qrURLImage

但是我的二维码有一个白色的背景图像，但我希望有一个透明的背景

我试过这样的方法：

let data = "1234567890".dataUsingEncoding(NSISOLatin1StringEncoding, allowLossyConversion: false)
let filter = CIFilter(name: "CIQRCodeGenerator")
filter!.setValue(data, forKey: "inputMessage")
filter!.setValue("Q", forKey: "inputCorrectionLevel")
qrcodeImage = filter!.outputImage
let transformedImage = qrcodeImage.imageByApplyingTransform(CGAffineTransformMakeScale(150, 150))
QRCodeImage.image = UIImage(CIImage: transformedImage)

QRCodeImage.backgroundColor = UIColor.clearColor()

QRCodeImage.backgroundcolor = UIColor(white: 1, alpha: 0.5)

let myChosenColor = UIColor(red:0.93, green:0.31, blue:0.23, alpha:1.00)
let qrURLImage = URL(string: "https://stackoverflow.com")?.qrImage(using: myChosenColor)
myQrImageView.image = qrURLImage

但这不起作用。

---

有什么想法吗？：）

似乎CIQRCodeGenerator过滤器总是使用黑白

您可以将输出传递到过滤器以将其转换为透明：

---

首先，您可能需要使用来交换黑白。

我认为关键点将位于背景的alpha上。您可以设置或减少alpha，减少或删除透明度。试着这样做：

let data = "1234567890".dataUsingEncoding(NSISOLatin1StringEncoding, allowLossyConversion: false)
let filter = CIFilter(name: "CIQRCodeGenerator")
filter!.setValue(data, forKey: "inputMessage")
filter!.setValue("Q", forKey: "inputCorrectionLevel")
qrcodeImage = filter!.outputImage
let transformedImage = qrcodeImage.imageByApplyingTransform(CGAffineTransformMakeScale(150, 150))
QRCodeImage.image = UIImage(CIImage: transformedImage)

QRCodeImage.backgroundColor = UIColor.clearColor()

QRCodeImage.backgroundcolor = UIColor(white: 1, alpha: 0.5)

let myChosenColor = UIColor(red:0.93, green:0.31, blue:0.23, alpha:1.00)
let qrURLImage = URL(string: "https://stackoverflow.com")?.qrImage(using: myChosenColor)
myQrImageView.image = qrURLImage

---

希望有帮助。

对于透明背景，你应该（运用你的直觉）这样做

//Create a CIFalseColor Filter
let colorFilter: CIFilter = CIFilter(name: "CIFalseColor")!

colorFilter.setDefaults()

colorFilter.setValue(yourQRFilter.outputImage!, forKey: "inputImage")

//Then set the background colour like this,
let transparentBG: CIColor = CIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.0)

colorFilter.setValue(qrColor, forKey: "inputColor0")

colorFilter.setValue(transparentBG, forKey: "inputColor1")

outputImage = colorFilter.outputImage!

我希望这会给您提供透明背景的QRCode图像。

这是我的代码：

func QRImageFromData(_ data: Data) -> UIImage? {

    let filter = CIFilter(name: "CIQRCodeGenerator")
    filter?.setValue(data, forKey: "inputMessage")
    //filter?.setValue("H", forKey: "inputCorrectionLevel")

    //change qrcode color : #1e3259
    let filterFalseColor = CIFilter(name: "CIFalseColor")
    filterFalseColor?.setDefaults()
    filterFalseColor?.setValue(filter?.outputImage, forKey: "inputImage")
    // convert method
    let cgColor: CGColor? = UIColor(hex: "#1e3259")?.cgColor
    let qrColor: CIColor = CIColor(cgColor: cgColor!)
    let transparentBG: CIColor = CIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.0)
    filterFalseColor?.setValue(qrColor, forKey: "inputColor0")
    filterFalseColor?.setValue(transparentBG, forKey: "inputColor1")


    if let image = filterFalseColor?.outputImage {
        let transform = CGAffineTransform(scaleX: 5.0, y: 5.0)
        return UIImage(ciImage: image.applying(transform),
            scale: 1.0,
            orientation: UIImageOrientation.up)
    } else {
        return nil
    }

}

---

我获得了一个透明背景的qr

添加以下扩展：

extension CIImage {
    /// Inverts the colors and creates a transparent image by converting the mask to alpha.
    /// Input image should be black and white.
    var transparent: CIImage? {
        return inverted?.blackTransparent
    }

    /// Inverts the colors.
    var inverted: CIImage? {
        guard let invertedColorFilter = CIFilter(name: "CIColorInvert") else { return nil }

        invertedColorFilter.setValue(self, forKey: "inputImage")
        return invertedColorFilter.outputImage
    }

    /// Converts all black to transparent.
    var blackTransparent: CIImage? {
        guard let blackTransparentFilter = CIFilter(name: "CIMaskToAlpha") else { return nil }
        blackTransparentFilter.setValue(self, forKey: "inputImage")
        return blackTransparentFilter.outputImage
    }

    /// Applies the given color as a tint color.
    func tinted(using color: UIColor) -> CIImage?
    {
        guard
            let transparentQRImage = transparent,
            let filter = CIFilter(name: "CIMultiplyCompositing"),
            let colorFilter = CIFilter(name: "CIConstantColorGenerator") else { return nil }

        let ciColor = CIColor(color: color)
        colorFilter.setValue(ciColor, forKey: kCIInputColorKey)
        let colorImage = colorFilter.outputImage

        filter.setValue(colorImage, forKey: kCIInputImageKey)
        filter.setValue(transparentQRImage, forKey: kCIInputBackgroundImageKey)

        return filter.outputImage!
    }
}


extension URL {

    func qrImage(using color: UIColor) -> UIImage? {
        let ciImage = qrCIImage?.tinted(using: color)
        return ciImage != nil ? UIImage(ciImage: ciImage!) : nil
    }

    var qrImage: UIImage? {
        return UIImage(ciImage: qrCIImage!)
    }

    /// Creates a QR code for the current URL in the given color.
    func qrCIImage(using color: UIColor) -> CIImage? {
        return qrCIImage?.tinted(using: color)
    }

    /// Returns a black and white QR code for this URL.
    var qrCIImage: CIImage? {
        guard let qrFilter = CIFilter(name: "CIQRCodeGenerator") else { return nil }
        let qrData = absoluteString.data(using: String.Encoding.ascii)
        qrFilter.setValue(qrData, forKey: "inputMessage")

        let qrTransform = CGAffineTransform(scaleX: 12, y: 12)
        return qrFilter.outputImage?.transformed(by: qrTransform)
    }

}

然后像这样使用：

let data = "1234567890".dataUsingEncoding(NSISOLatin1StringEncoding, allowLossyConversion: false)
let filter = CIFilter(name: "CIQRCodeGenerator")
filter!.setValue(data, forKey: "inputMessage")
filter!.setValue("Q", forKey: "inputCorrectionLevel")
qrcodeImage = filter!.outputImage
let transformedImage = qrcodeImage.imageByApplyingTransform(CGAffineTransformMakeScale(150, 150))
QRCodeImage.image = UIImage(CIImage: transformedImage)

QRCodeImage.backgroundColor = UIColor.clearColor()

QRCodeImage.backgroundcolor = UIColor(white: 1, alpha: 0.5)

let myChosenColor = UIColor(red:0.93, green:0.31, blue:0.23, alpha:1.00)
let qrURLImage = URL(string: "https://stackoverflow.com")?.qrImage(using: myChosenColor)
myQrImageView.image = qrURLImage

---

在myQrImageView.image中，您将看到一个透明背景的qr图像：

除了@jtbandes的答案之外，我还编写了一些代码，这样也可以帮助其他人

extension UIImage {

    func transparentBackground() -> UIImage? {
        let context = CIContext(options: nil)
        let filter = CIFilter(name: "CIMaskToAlpha")
        filter?.setDefaults()
        filter?.setValue(self.ciImage, forKey: kCIInputImageKey)
        if let output = filter?.outputImage,
           let imageRef = context.createCGImage(output, from: output.extent) {
            return UIImage(cgImage: imageRef)
        }
        return nil
    }

    func invertColor() -> UIImage? {
        let filter = CIFilter(name: "CIColorInvert")
        filter?.setDefaults()
        filter?.setValue(self.ciImage, forKey: kCIInputImageKey)
        if let output = filter?.outputImage {
            return UIImage(ciImage: output)
        }
        return nil
    }

}

像这样使用它

yourUIImage.invertColor()?.transparentBackground()

---

transparentBackground（）

函数将删除黑色并保留白色，因为

invertColor（）

将用白色替换黑色

您可能必须在Library中更改此项，我如何才能做到这一点？哦，对不起@jtbandes的一个答案很好；与此相关的是，你有一个代码，在Arun Amayana提出的答案上可能对你有用：问题是，这个解决方案不是一个快速的解决方案：（这个呢？QRCodeImage.backgroundColor=UIColor.clearColor（））哦，再次抱歉。也许这里你有一些不同的东西：很好的挖掘：）（拇指支撑）很棒的家伙，但你知道，一个小小的代码示例不会有什么坏处！

extension UIImage {
    func alpha(_ value: CGFloat) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(size, false, scale)
        draw(at: CGPoint.zero, blendMode: .normal, alpha: value)
        let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return image
    }
}