如何在 swift 中 http 发布特殊字符

我使用以下命令将电子邮件和密码发布到我的服务器（php 脚本）。我遇到的问题是密码包含一个特殊字符（特别是&符号）似乎正在被剥离。我认为是因为它认为它的分隔变量被传递。我怎样才能传递这个字符而不剥离它？

let myURL = NSURL(string: "my script url here")
let request = NSMutableURLRequest(URL: myURL!)
request.HTTPMethod = "POST"

let postString = "email=\(userEmailText)&password=\(userPasswordText)"

request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)

你应该谨慎使用NSURLComponents因为NSURLQueryItem可能会百分比转义有问题的字符，&，它没有%转义+字符（PHP 将其解释为空格，符合W3C 规范x-www-form-urlencoded http://www.w3.org/TR/html5/forms.html#application/x-www-form-urlencoded-encoding-algorithm). As the queryItems文档 https://developer.apple.com/documentation/foundation/nsurlcomponents/1407752-queryitems says:

Note

RFC 3986 https://www.ietf.org/rfc/rfc3986.txt指定 URL 的查询组件中哪些字符必须进行百分比编码，但不指定应如何解释这些字符。使用分隔键值对是一种常见约定，但并未由规范标准化。因此，您可能会遇到与遵循此约定的其他实现的互操作性问题。

潜在互操作性问题的一个值得注意的例子是加号 (+) 字符的处理：

根据 RFC 3986，加号是查询中的有效字符，不需要进行百分比编码。然而，根据W3C 对 URI 寻址的建议 https://www.w3.org/Addressing/URL/4_URI_Recommentations.html，加号被保留作为查询字符串中空格的速记符号（例如，?greeting=hello+world).

如果您的值可能包含+特点：

1. 您可以构建自己的CharacterSet要转义的字符然后使用addingPercentEncodingForURLQueryValue在斯威夫特 3 中：

   extension String {
   
       /// Returns a new string made from the `String` by replacing all characters not in the unreserved
       /// character set (as defined by RFC3986) with percent encoded characters.
   
       func addingPercentEncodingForURLQueryValue() -> String? {
           let allowedCharacters = CharacterSet.urlQueryValueAllowed()
           return addingPercentEncoding(withAllowedCharacters: allowedCharacters)
       }
   
   }
   
   extension CharacterSet {
   
       /// Returns the character set for characters allowed in the individual parameters within a query URL component.
       ///
       /// The query component of a URL is the component immediately following a question mark (?).
       /// For example, in the URL `http://www.example.com/index.php?key1=value1#jumpLink`, the query
       /// component is `key1=value1`. The individual parameters of that query would be the key `key1`
       /// and its associated value `value1`.
       ///
       /// According to RFC 3986, the set of unreserved characters includes
       ///
       /// `ALPHA / DIGIT / "-" / "." / "_" / "~"`
       ///
       /// In section 3.4 of the RFC, it further recommends adding `/` and `?` to the list of unescaped characters
       /// for the sake of compatibility with some erroneous implementations, so this routine also allows those
       /// to pass unescaped.
   
   
       static func urlQueryValueAllowed() -> CharacterSet {
           return CharacterSet(charactersIn: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._~/?")
       }
   
   }
   

2. Alamofire 采用了类似的方法，但从另一个方向实现这一点，即抓住.urlQueryAllowed字符集（很接近，但不太正确），并取出 RFC 3986 中标识的保留字符。在 Swift 3 中：

   /// Returns a percent-escaped string following RFC 3986 for a query string key or value.
   ///
   /// RFC 3986 states that the following characters are "reserved" characters.
   ///
   /// - General Delimiters: ":", "#", "[", "]", "@", "?", "/"
   /// - Sub-Delimiters: "!", "$", "&", "'", "(", ")", "*", "+", ",", ";", "="
   ///
   /// In RFC 3986 - Section 3.4, it states that the "?" and "/" characters should not be escaped to allow
   /// query strings to include a URL. Therefore, all "reserved" characters with the exception of "?" and "/"
   /// should be percent-escaped in the query string.
   ///
   /// - parameter string: The string to be percent-escaped.
   ///
   /// - returns: The percent-escaped string.
   public func escape(_ string: String) -> String {
       let generalDelimitersToEncode = ":#[]@" // does not include "?" or "/" due to RFC 3986 - Section 3.4
       let subDelimitersToEncode = "!$&'()*+,;="
   
       var allowedCharacterSet = CharacterSet.urlQueryAllowed
       allowedCharacterSet.remove(charactersIn: "\(generalDelimitersToEncode)\(subDelimitersToEncode)")
   
       var escaped = ""
   
       //==========================================================================================================
       //
       //  Batching is required for escaping due to an internal bug in iOS 8.1 and 8.2. Encoding more than a few
       //  hundred Chinese characters causes various malloc error crashes. To avoid this issue until iOS 8 is no
       //  longer supported, batching MUST be used for encoding. This introduces roughly a 20% overhead. For more
       //  info, please refer to:
       //
       //      - https://github.com/Alamofire/Alamofire/issues/206
       //
       //==========================================================================================================
       if #available(iOS 8.3, *) {
           escaped = string.addingPercentEncoding(withAllowedCharacters: allowedCharacterSet) ?? string
       } else {
           let batchSize = 50
           var index = string.startIndex
   
           while index != string.endIndex {
               let startIndex = index
               let endIndex = string.index(index, offsetBy: batchSize, limitedBy: string.endIndex) ?? string.endIndex
               let range = startIndex..<endIndex
   
               let substring = string.substring(with: range)
   
               escaped += substring.addingPercentEncoding(withAllowedCharacters: allowedCharacterSet) ?? substring
   
               index = endIndex
           }
       }
   
       return escaped
   }
   

然后，您可以使用上述内容对请求正文中的键和值进行百分比转义，例如：

let parameters = ["email" : email, "password" : password]
request.httpBody = parameters
    .map { (key, value) in
        let escapedKey = key.addingPercentEncodingForURLQueryValue()!
        let escapedValue = value.addingPercentEncodingForURLQueryValue()!
        return "\(escapedKey)=\(escapedValue)"
    }
    .joined(separator: "&")
    .data(using: .utf8)

对于上述内容的 Swift 2 版本，请参阅此答案的先前修订版 https://stackoverflow.com/revisions/35912606/2.