如何在 Swift 中转义 HTTP 参数

Question

我正在尝试向HTTP服务器发帖

顺便说一下，这是我的代码：

  func sendPostToUrl(url:String, withParams params: [String: String?] ) {
    var request = NSMutableURLRequest(URL: NSURL(string: url)!)
    var session = NSURLSession.sharedSession()
    request.HTTPMethod = "POST"
    var err: NSError?
    var bodyData = ""
    for (key,value) in params{
        if (value==nil){ continue }
        let scapedKey = key.stringByAddingPercentEncodingWithAllowedCharacters(
                 .URLHostAllowedCharacterSet())!
        let scapedValue = value!.stringByAddingPercentEncodingWithAllowedCharacters(
                .URLHostAllowedCharacterSet())!
        bodyData += "(scapedKey)=(scapedValue)&"
    }
    request.HTTPBody = bodyData.dataUsingEncoding
               (NSUTF8StringEncoding, allowLossyConversion: true)
    var task = session.dataTaskWithRequest(request, 
    completionHandler: {data, response, error -> Void in
        println("Response: (response)")
        let dataString = NSString(data: data, encoding: NSUTF8StringEncoding)
        println("Data: (dataString)")
    })
    task.resume()
}

它有效，但并不完美。如果我以这种方式调用函数：

    client.sendPostToUrl("http://novagecko.com/tests/test.php", 
        withParams: ["hello":"world","inject":"param1=value1&param2=value2"]);

服务器检测 3 个 post 字段（键为 hello、inject 和 param2），而不是 2 个。

如何转义键和值？

我还能做些什么来改进方法吗？

Answer 1

如果您可以定位到 iOS 8（感谢@Rob），请使用 NSURLComponents 来转义您的参数：

import Foundation
func encodeParameters(#params: [String: String]) -> String {
    var queryItems = map(params) { NSURLQueryItem(name:$0, value:$1)}
    var components = NSURLComponents()
    components.queryItems = queryItems
    return components.percentEncodedQuery ?? ""
}

现在encodeParameters(params:["hello":"world","inject":"param1=value1&param2=value2"])如您所料返回hello=world&inject=param1%3Dvalue1%26param2%3Dvalue2。

否则，创建字符集以正确转义值的最佳方法是：

var safeCharacterSet = NSCharacterSet.URLQueryAllowedCharacterSet().mutableCopy()
safeCharacterSet.removeCharactersInString("&=")

并查看@rintaro的答案，以正确使用过滤器/映射以良好的方式执行编码。

Answer 2

似乎，NSCharacterSet没有相关的设置。

所以，添加这个

extension NSCharacterSet {
    class func URLUnreservedCharacterSet() -> NSCharacterSet {
        return self(charactersInString: "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_.~")
    }
}

然后

var bodyData = ""
var safeCharacterSet = NSCharacterSet.URLUnreservedCharacterSet()
for (key,value) in params{
    if (value==nil){ continue }
    let scapedKey = key.stringByAddingPercentEncodingWithAllowedCharacters(safeCharacterSet)!
    let scapedValue = value!.stringByAddingPercentEncodingWithAllowedCharacters(safeCharacterSet)!
    bodyData += "(scapedKey)=(scapedValue)&"
}

---

如下@Rob在评论中的建议，这里有一个map和join的例子：

let params:[String:String?] = ["fubar":nil, "hello":"world", "inject":"param1=value1&param2=value2"]
let safeCharacterSet = NSCharacterSet.URLUnreservedCharacterSet()
let pairs = filter(params, {$1 != nil}).map { (key, value) -> String in
    let _key = key.stringByAddingPercentEncodingWithAllowedCharacters(safeCharacterSet)!
    let _val = value!.stringByAddingPercentEncodingWithAllowedCharacters(safeCharacterSet)!
    return _key + "=" + _val
}
let bodyData = "&".join(pairs)

这更好，因为结果中没有尾随&。