Swift 3 - 生成的 QR 码 UIImage 要附加到电子邮件但我收到错误 "found nil while unwrapping an Optional value"

Question

我有 QR 码生成器，它显示图像到我的 qrImageView UIImageView。

现在，我要做的是将二维码图像附加到电子邮件中。尝试了下面指定的代码，但出现错误 "found nil while unwrapping an Optional value".

请帮忙！

二维码生成功能

  func generateQRCode(from string:String) -> UIImage? {

    let data =  string.data(using: String.Encoding.isoLatin1)

    if let filter = CIFilter(name:"CIQRCodeGenerator") {
        filter.setValue(data, forKey: "inputMessage")
        let transform = CGAffineTransform(scaleX: 100, y: 100)

        if let output = filter.outputImage?.applying(transform) {
            return UIImage(ciImage: output)
        }
    }
    return nil
}

@IBAction func generateAction(_ sender: Any) {

    if let actualText = qrCodeTextField.text {
        let image = generateQRCode(from: actualText)
        qrImageView.image = image
    }



}

用于将二维码附加到电子邮件的代码

func configureMailController() -> MFMailComposeViewController {
    let mailComposerVC = MFMailComposeViewController()

    mailComposerVC.mailComposeDelegate = self

    mailComposerVC.setToRecipients(["tsm@yahoo.com"])
    mailComposerVC.setSubject("\(subject) QR Code")
    mailComposerVC.setMessageBody("Please see attached QR Code", isHTML: false)

    //Add Image as Attachment

    if let image = qrImageView.image {
        let data: NSData = UIImagePNGRepresentation(image)! as NSData

        mailComposerVC.addAttachmentData(data as Data, mimeType: "image/png", fileName: "image")

    }


    return mailComposerVC

}

Answer 1

试试这个，

if let image = qrImageView.image { 
    let data = UIImagePNGRepresentation(image) as NSData?
}

而不是

if let image = qrImageView.image {
    let data = UIImagePNGRepresentation(image)! as NSData
}

似乎这是代码中唯一强制解包值的部分。

Answer 2

这对我有用。我必须先将 CIImage 转换为 UIImage，以便 QRCode 可以附加到电子邮件

func convert(cmage:CIImage) -> UIImage
{       
    let context:CIContext = CIContext.init(options: nil)
    let cgImage:CGImage = context.createCGImage(cmage, from: cmage.extent)!        
    let image:UIImage = UIImage.init(cgImage: cgImage)        
    return image
}

来源：

Swift 3 - 生成的 QR 码 UIImage 要附加到电子邮件但我收到错误 "found nil while unwrapping an Optional value"

Swift 3 - Generated QR Code UIImage to be attached to email but I get error "found nil while unwrapping an Optional value"

qr-code

uiimage

email-attachments

unwrap

swift3