Question

我在下面粘贴了我的代码。从本质上讲，我得到了一个SDK，该SDK具有一个JSON字符串，然后必须解析该JSON字符串，以便获取从中生成QR码的base64字符串。我一直在努力，但是代码错误出现在“ let nsd = ...”行，并显示以下消息：“线程1：致命错误：在展开可选值时意外发现nil”

对我要去哪里的任何帮助将不胜感激。对于Swift和一般编程，我是一个新手，因此发现这非常具有挑战性。我也不认为我将响应正确转换为JSON，因为这是第一次出错的地方。

func qrCodeGenerator(payload : String) {

    guard let response = /response as a string from SDK/ else {return}


    /* convert response string to an NSData response, so as to convert to JSON in the code below */
    let nsd: NSData = NSData(base64Encoded: response, options: NSData.Base64DecodingOptions.ignoreUnknownCharacters)!

    var jsonResponse = JSON.null

    do {

        /* convert the response to a json object */
        try jsonResponse = JSONSerialization.jsonObject(with: nsd as Data, options: []) as! JSON

        /* enter the result array, as the base64 string is contained there */
        var result = jsonResponse["result"][0]
        var resqr_64 = result["qr_b64"].stringValue

        print(resqr_64)

        var base64string = resqr_64

        /*The base64 string lies beyond the comma*/
        var base64image = String(base64string.split(separator: ",")[1]) as String

        var decodeString : NSData = NSData(base64Encoded: base64image, options: [])!
        var decodedimage: UIImage = UIImage(data: decodeString as Data)!

        QRCodeImageView.image = decodedimage
    } catch {
        print(error)
    }
}

任何帮助将不胜感激！非常感谢。

Answer 1

 if let decodedData = Data(base64Encoded: (dataDict["THUMBNAIL"] as? String)! , options: .ignoreUnknownCharacters{

            self.imgThumb.image = UIImage(data: decodedData)

        }

尝试使用此代码从base64字符串获取图像：）

Answer 2

代码中有两个严重的问题：

1）响应很可能是常规JSON字符串（非base64编码），无法从字符串初始化base64编码的Data。
2）您不能使用SwiftyJSON初始化程序强制将JSONSerialization的结果强制转换为JSON。

请尝试

func qrCodeGenerator(payload : String) {

    guard let response = /response as a string from SDK/ else {return}


    /* convert response string to an NSData response, so as to convert to JSON in the code below */
    let data = Data(response.utf8)

    do {

        /* convert the response to a json object */
        let jsonResponse = try JSON(data)

        /* enter the result array, as the base64 string is contained there */
        let result = jsonResponse["result"][0]
        let base64string = result["qr_b64"].stringValue

        print(base64string)

        /*The base64 string lies beyond the comma*/
        let base64image = String(base64string.split(separator: ",")[1])

        let decodeString = Data(base64Encoded: base64image)!
        let decodedimage = UIImage(data: decodeString)!

        QRCodeImageView.image = decodedimage
    } catch {
        print(error)
    }
}

注意：您是否不担心一堆 Variable 'xyz' was never mutated; consider changing to 'let' constant 警告？

如何解码在JSON字符串中找到的base 64字符串以生成UIImage？

2 个答案: