php - 如何在 swift 中 http 发布特殊字符

Question

我正在使用以下内容将电子邮件和密码发送到我的服务器(php 脚本)。我遇到的问题是密码包含一个特殊的字符(特别是 & 符号)，它似乎被剥离了。我想是因为它认为它的分隔变量被传递了。我如何在不剥离它的情况下传递这个字符？

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)

Answer 1

你应该小心使用 NSURLComponents 因为 NSURLQueryItem 可能会百分号转义有问题的字符，&，它不会百分比转义 + 字符(PHP 将解释为符合 W3C Specification for x-www-form-urlencoded 的空格)。正如 the queryItems documentation 所说:

Note

RFC 3986 specifies which characters must be percent-encoded in the query component of a URL, but not how those characters should be interpreted. The use of delimited key-value pairs is a common convention, but isn't standardized by a specification. Therefore, you may encounter interoperability problems with other implementations that follow this convention.

One notable example of potential interoperability problems is how the plus sign (+) character is handled:

According to RFC 3986, the plus sign is a valid character within a query, and doesn't need to be percent-encoded. However, according to the W3C recommendations for URI addressing, the plus sign is reserved as shorthand notation for a space within a query string (for example, ?greeting=hello+world).

如果您的值可能包含 + 字符，那么对于您自己添加到 URL 查询的值，这会留下一些百分比转义选项:

1. 您可以构建自己的要转义字符的 CharacterSet，然后在 Swift 3 中使用 addingPercentEncodingForURLQueryValue:

   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，但从另一个方向进行，即抓取 .urlQueryAllowed 字符集(接近但不太正确)，并取出保留字符在 RFC 3986 中确定。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
   }
   

然后您可以使用上面的代码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)

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有关上述内容的 Swift 2 版本，请参阅 previous revision of this answer。