swift - 如何对图像进行URI编码？

我在这里阅读alchemy-API文档:

http://www.alchemyapi.com/api/image-tagging/image.html

他们说图片必须经过URI编码...这到底是什么意思？

这是否意味着将图像转换为base64字符串，然后将其传递给请求？

我已经尝试过，但是收到了HTTP 414错误-请求URI太大。

这是我发出请求的代码:

    @IBAction func analyzeImage(sender: UIButton) {

    var imageData = UIImagePNGRepresentation(mainImage.image)
    let base64ImageString = imageData.base64EncodedStringWithOptions(.allZeros)
    let requestString = ENDPOINT+"?apikey="+API_KEY+"&image="+base64ImageString+"&outputMode=json"


    let url = NSURL(string: requestString)
    let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in
        println(NSString(data: data, encoding: NSUTF8StringEncoding))
    }

    task.resume()
}

编辑:我考虑了Dijkgraaf的建议，即使用POST请求而不是GET来解决URI长度问题。我正在使用Alamofire库来执行此操作。这是我的代码:

@IBAction func analyzeImage(sender: UIButton) {

    var imageData = UIImagePNGRepresentation(mainImage.image)
    let base64ImageString = imageData.base64EncodedStringWithOptions(.allZeros)

    let params = [
        "apikey" : API_KEY,
        "image"  : base64ImageString,
        "outputMode" : "json"]

    var manager = Manager.sharedInstance
    //Passing all the headers you want!
    manager.session.configuration.HTTPAdditionalHeaders = [
        "Content-Type": "application/x-www-form-urlencoded"
    ]
    manager.request(.POST, ENDPOINT, parameters:params, encoding: .URL)
        .response { (request, response, data, error) in
            println(request)
            println(response)
            println(error)
    }
}

但是，尝试此操作时出现“无法分析:下游问题”错误。

这是控制台输出:

<NSMutableURLRequest: 0x1742040c0> { URL: http://access.alchemyapi.com/calls/image/ImageGetRankedImageKeywords }
Optional(<NSHTTPURLResponse: 0x17082c1e0> { URL: http://access.alchemyapi.com/calls/image/ImageGetRankedImageKeywords } { status code: 200, headers {
    "Access-Control-Allow-Origin" = "*";
    "Cache-Control" = "no-cache";
    Connection = "keep-alive";
    "Content-Length" = 326;
    "Content-Type" = "application/json";
    Date = "Mon, 08 Jun 2015 05:59:22 GMT";
    Server = nginx;
    "X-AlchemyAPI-CurrentVersion" = "12.15";
    "X-AlchemyAPI-Error-Msg" = "cannot-analyze:downstream-issue";
    "X-AlchemyAPI-Key" = [API KEY HIDDEN];
    "X-AlchemyAPI-Params" = "sentiment=0&knowledgeGraph=0&detectedLanguage=unknown&submitLanguage=detect";
    "X-AlchemyAPI-Status" = ERROR;
    "X-AlchemyAPI-Total-Transactions" = 0;
} })
nil

不知道出了什么问题，但是Alchemy文档确实声明POST请求应将“Content-Type” header 设置为“application/x-www-form-urlencoded”，无论如何都不会发生我尝试设置。这可能是问题吗？

编辑:我尝试过仅发布原始图像数据，正如Dijkgraaf建议的那样:

    @IBAction func analyzeImage(sender: UIButton) {

    var imageData = UIImagePNGRepresentation(mainImage.image)
    //let base64ImageString = imageData.base64EncodedStringWithOptions(.allZeros)
    var request = HTTPTask()
    request.requestSerializer = HTTPRequestSerializer()
    request.requestSerializer.headers["Content-Type"] = "application/x-www-form-urlencoded"
    let params: Dictionary<String,AnyObject> = [
        "apikey" : API_KEY,
        "imagePostMode" : "raw",
        "image" : imageData,
        "outputMode" : "json"]
    request.POST(ENDPOINT, parameters: params, completionHandler: {(response: HTTPResponse) in
        println(response.headers)
    })

}

但是我仍然遇到相同的无法分析下游问题的错误。

最佳答案

使用imagePostMode raw时，需要将图像数据作为POST请求的主体发送，并且参数应包含在端点URL中(例如ENDPOINT =“http://access.alchemyapi.com/calls/image/ImageGetRankedImageKeywords？apikey = API_KEY＆outputMode = json＆imagePostMode = raw“)。我没有与Swift合作，所以我不知道执行此操作的最佳方法，但这与您可能期望的有所不同。

关于swift - 如何对图像进行URI编码？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/30700941/