swift – 如何URI编码图像？

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

他们说图像必须是URI编码的…究竟是什么意思？

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？

我试过了,但收到了http 414错误 – 请求URI太大了.

这是我的代码,其中提出了请求：

@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：我考虑到Dijkgraaf建议使用POST请求而不是GET来解决URI长度问题.我正在使用Alamofire库来做到这一点.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,data,error) in
            println(request)
            println(response)
            println(error)
    }
}

但是,当我尝试这个时,我得到一个“无法分析：下游问题”的错误.

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Alchemy文档确实说明POST请求应该将“Content-Type”标题设置为“application / x-www-form-urlencoded”,这似乎不会发生,无论什么我试着设定.这可能是问题吗？

编辑：我再次尝试POST原始图像数据,Dijkgraaf建议：

@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)
    })

}

但我仍然得到相同的不能 – 再次分析下游问题错误.