使用Swift中的URLComponents对“+”进行编码 [英] Encode '+' using URLComponents in Swift

问题描述

这是我将查询参数添加到基本URL的方法：

This is how I add a query params to a base URL:

let baseURL: URL = ...
let queryParams: [AnyHashable: Any] = ...
var components = URLComponents(url: baseURL, resolvingAgainstBaseURL: false)
components?.queryItems = queryParams.map { URLQueryItem(name: $0, value: "\($1)") }
let finalURL = components?.url

如果其中一个值包含 + 符号，则会出现问题。由于某些原因，它在最终URL中未编码为％2B ，而是保持 + 。如果我自己编码并传递％2B ， NSURL 编码％和'plus'变成％252B 。

The problem emerges when one of values contains a + symbol. For some reason it's not encoded to %2B in the final URL, instead it stays +. If I do encoding myself and pass %2B, NSURL encodes % and the 'plus' becomes %252B.

问题是如何才能％2B 在 NSURL 的实例中？

The question is how can I have %2B in the instance of NSURL?

PS我知道，如果我自己构造一个查询字符串然后只是将结果传递给 NSURL 的构造函数 init，我甚至不会遇到这个问题？（字符串：）。

P.S. I know, I wouldn't even have this problem if I constructed a query string myself and then simply pass a result to the NSURL's constructor init?(string:).

推荐答案

正如其他答案所指出的，+字符在
a查询字符串中有效，这也在
中说明 查询项目 文档。

As pointed out in the other answers, the "+" character is valid in a query string, this is also stated in the query​Items documentation.

另一方面，
< a href =https://www.w3.org/Addressing/URL/4_URI_Recommentations.html\"rel =noreferrer>针对URI寻址的W3C建议
说明

On the other hand, the W3C recommendations for URI addressing state that

在查询字符串中，加号被保留为空格的简写表示法。因此，必须对真正的加号进行编码。此方法用于使查询URI更容易在不允许空格的系统中传递。

Within the query string, the plus sign is reserved as shorthand notation for a space. Therefore, real plus signs must be encoded. This method was used to make query URIs easier to pass in systems which did not allow spaces.

这可以通过手动实现使用自定义字符集构建
编码查询字符串的百分比：

This can be achieved by "manually" building the percent encoded query string, using a custom character set:

let queryParams = ["foo":"a+b", "bar": "a-b", "baz": "a b"]
var components = URLComponents()

var cs = CharacterSet.urlQueryAllowed
cs.remove("+")

components.scheme = "http"
components.host = "www.example.com"
components.path = "/somepath"
components.percentEncodedQuery = queryParams.map {
    $0.addingPercentEncoding(withAllowedCharacters: cs)!
    + "=" + $1.addingPercentEncoding(withAllowedCharacters: cs)!
}.joined(separator: "&")

let finalURL = components.url
// http://www.example.com/somepath?bar=a-b&baz=a%20b&foo=a%2Bb

另一种选择是后...编码生成的
百分比编码的查询字符串中的加号字符：

Another option is to "post-encode" the plus character in the generated percent-encoded query string:

let queryParams = ["foo":"a+b", "bar": "a-b", "baz": "a b"]
var components = URLComponents()
components.scheme = "http"
components.host = "www.example.com"
components.path = "/somepath"
components.queryItems = queryParams.map { URLQueryItem(name: $0, value: $1) }
components.percentEncodedQuery = components.percentEncodedQuery?
    .replacingOccurrences(of: "+", with: "%2B")

let finalURL = components.url
print(finalURL!)
// http://www.example.com/somepath?bar=a-b&baz=a%20b&foo=a%2Bb

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