带参数的快速获取请求

Question

我对swift非常陌生，所以我的代码中可能会有很多错误，但我试图实现的是向带有paramters的本地主机服务器发送get请求。更重要的是，我试图实现它，因为我的函数接受两个参数baseurl:string，params:nsdictionary。我不确定如何将这两者结合到实际的URLRequest中？以下是我到目前为止所尝试的

    func sendRequest(url:String,params:NSDictionary){
       let urls: NSURL! = NSURL(string:url)
       var request = NSMutableURLRequest(URL:urls)
       request.HTTPMethod = "GET"
       var data:NSData! =  NSKeyedArchiver.archivedDataWithRootObject(params)
       request.HTTPBody = data
       println(request)
       var session = NSURLSession.sharedSession()
       var task = session.dataTaskWithRequest(request, completionHandler:loadedData)
       task.resume()

    }

}

func loadedData(data:NSData!,response:NSURLResponse!,err:NSError!){
    if(err != nil){
        println(err?.description)
    }else{
        var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
        println(jsonResult)

    }

}

Answer 1

在构建get请求时，没有请求的正文，而是所有内容都在URL上进行。要构建URL（以及正确的百分比转义），还可以使用urlcomponents。

var url = URLComponents(string: "https://www.google.com/search/")!

url.queryItems = [
    URLQueryItem(name: "q", value: "War & Peace")
]

唯一的诀窍是，大多数web服务需要+字符百分比转义（因为它们会将其解释为application/x-www-form-urlencoded规范规定的空格字符）。但是urlcomponents不会对其进行百分比转义。Apple认为+是查询中的有效字符，因此不应该转义。从技术上讲，它们是正确的，在URI查询中允许这样做，但是在application/x-www-form-urlencoded请求中有特殊的含义，并且不应该不转义地传递。

Apple承认我们必须对+字符进行百分比转义，但建议我们手动转义：

var url = URLComponents(string: "https://www.wolframalpha.com/input/")!

url.queryItems = [
    URLQueryItem(name: "i", value: "1+2")
]

url.percentEncodedQuery = url.percentEncodedQuery?.replacingOccurrences(of: "+", with: "%2B")

这是一个不优雅的解决方案，但它是有效的，如果您的查询可能包含+字符，并且您有一个将它们解释为空格的服务器，苹果就会建议您这样做。

因此，将其与SendRequest例程结合起来，您将得到如下内容：

func sendRequest(_ url: String, parameters: [String: String], completion: @escaping ([String: Any]?, Error?) -> Void) {
    var components = URLComponents(string: url)!
    components.queryItems = parameters.map { (key, value) in 
        URLQueryItem(name: key, value: value) 
    }
    components.percentEncodedQuery = components.percentEncodedQuery?.replacingOccurrences(of: "+", with: "%2B")
    let request = URLRequest(url: components.url!)
    
    let task = URLSession.shared.dataTask(with: request) { data, response, error in
        guard
            let data = data,                              // is there data
            let response = response as? HTTPURLResponse,  // is there HTTP response
            200 ..< 300 ~= response.statusCode,           // is statusCode 2XX
            error == nil                                  // was there no error
        else {
            completion(nil, error)
            return
        }
        
        let responseObject = (try? JSONSerialization.jsonObject(with: data)) as? [String: Any]
        completion(responseObject, nil)
    }
    task.resume()
}

sendRequest("someurl", parameters: ["foo": "bar"]) { responseObject, error in
    guard let responseObject = responseObject, error == nil else {
        print(error ?? "Unknown error")
        return
    }

    // use `responseObject` here
}