斯威夫特3:

let originalString = "http://www.ihtc.cc?name=htc&title=iOS开发工程师"

1. encodingQuery:

let escapedString = originalString.addingPercentEncoding(withAllowedCharacters:NSCharacterSet.urlQueryAllowed)

结果:

"http://www.ihtc.cc?name=htc&title=iOS%E5%BC%80%E5%8F%91%E5%B7%A5%E7%A8%8B%E5%B8%88" 

2. 编码网址：

let escapedString = originalString.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)

结果:

"http:%2F%2Fwww.ihtc.cc%3Fname=htc&title=iOS%E5%BC%80%E5%8F%91%E5%B7%A5%E7%A8%8B%E5%B8%88"

斯威夫特3

在Swift 3中增加了percentencoding

let originalString = "test/test"
let escapedString = originalString.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)
print(escapedString!)

输出:

测试%2F测试

斯威夫特1

在ios7及以上版本中，有stringByAddingPercentEncodingWithAllowedCharacters

var originalString = "test/test"
var escapedString = originalString.stringByAddingPercentEncodingWithAllowedCharacters(.URLHostAllowedCharacterSet())
println("escapedString: \(escapedString)")

输出:

测试%2F测试

以下是有用的(倒置的)字符集:

URLFragmentAllowedCharacterSet  "#%<>[\]^`{|}
URLHostAllowedCharacterSet      "#%/<>?@\^`{|}
URLPasswordAllowedCharacterSet  "#%/:<>?@[\]^`{|}
URLPathAllowedCharacterSet      "#%;<>?[\]^`{|}
URLQueryAllowedCharacterSet     "#%<>[\]^`{|}
URLUserAllowedCharacterSet      "#%/:<>?@[\]^`

如果你想要转义一组不同的字符，创建一个set: 添加“=”字符的示例:

var originalString = "test/test=42"
var customAllowedSet =  NSCharacterSet(charactersInString:"=\"#%/<>?@\\^`{|}").invertedSet
var escapedString = originalString.stringByAddingPercentEncodingWithAllowedCharacters(customAllowedSet)
println("escapedString: \(escapedString)")

输出:

测试% 2Ftest % 3D42

使用实例验证集合中不存在的ascii字符。

func printCharactersInSet(set: NSCharacterSet) {
    var characters = ""
    let iSet = set.invertedSet
    for i: UInt32 in 32..<127 {
        let c = Character(UnicodeScalar(i))
        if iSet.longCharacterIsMember(i) {
            characters = characters + String(c)
        }
    }
    print("characters not in set: \'\(characters)\'")
}

对于Swift 5到endcode字符串

func escape(string: String) -> String {
    let allowedCharacters = string.addingPercentEncoding(withAllowedCharacters: CharacterSet(charactersIn: ":=\"#%/<>?@\\^`{|}").inverted) ?? ""
    return allowedCharacters
}

如何使用?

let strEncoded = self.escape(string: "http://www.edamam.com/ontologies/edamam.owl#recipe_e2a1b9bf2d996cbd9875b80612ed9aa4")
print("escapedString: \(strEncoded)")

帮助我的是，我创建了一个单独的NSCharacterSet，并在一个UTF-8编码的字符串上使用它，即textToEncode来生成所需的结果:

var queryCharSet = NSCharacterSet.urlQueryAllowed
queryCharSet.remove(charactersIn: "+&?,:;@+=$*()")
    
let utfedCharacterSet = String(utf8String: textToEncode.cString(using: .utf8)!)!
let encodedStr = utfedCharacterSet.addingPercentEncoding(withAllowedCharacters: queryCharSet)!
    
let paramUrl = "https://api.abc.eu/api/search?device=true&query=\(escapedStr)"

Swift 4 & 5

要在URL中编码参数，我发现使用. alphanumics字符集是最简单的选择:

let urlEncoded = value.addingPercentEncoding(withAllowedCharacters: .alphanumerics)
let url = "http://www.example.com/?name=\(urlEncoded!)"

使用URL编码的任何标准字符集(如. urlqueryallowed或. urlhostallowed)都不起作用，因为它们不排除=或&字符。

注意，通过使用. alphannumeric，它将编码一些不需要编码的字符(如-，.，_或~ -参见2.3。RFC 3986中的非保留字符)。我发现使用. alphanumics比构造一个自定义字符集更简单，并且不介意编码一些额外的字符。如果这困扰你，构造一个自定义字符集，如描述如何百分比编码URL字符串，例如:

// Store allowed character set for reuse (computed lazily).
private let urlAllowed: CharacterSet =
    .alphanumerics.union(.init(charactersIn: "-._~")) // as per RFC 3986

extension String {
    var urlEncoded: String? {
        return addingPercentEncoding(withAllowedCharacters: urlAllowed)
    }
}

let url = "http://www.example.com/?name=\(value.urlEncoded!)"

警告:urlEncoded参数是强制打开的。对于无效的unicode字符串，它可能会崩溃。参见为什么String.addingPercentEncoding()的返回值是可选的?而不是强制展开urlEncoded!你可以使用urlEncoded ??或者if let urlEncoded = urlEncoded{…}。

我自己也需要这个，所以我写了一个字符串扩展，既允许URLEncoding字符串，以及更常见的最终目标，将参数字典转换为“GET”风格的URL参数:

extension String {
    func URLEncodedString() -> String? {
        var escapedString = self.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)
        return escapedString
    }
    static func queryStringFromParameters(parameters: Dictionary<String,String>) -> String? {
        if (parameters.count == 0)
        {
            return nil
        }
        var queryString : String? = nil
        for (key, value) in parameters {
            if let encodedKey = key.URLEncodedString() {
                if let encodedValue = value.URLEncodedString() {
                    if queryString == nil
                    {
                        queryString = "?"
                    }
                    else
                    {
                        queryString! += "&"
                    }
                    queryString! += encodedKey + "=" + encodedValue
                }
            }
        }
        return queryString
    }
}

享受吧!