基于Ramis回答的Swift 3解决方案:

extension String {
    func withReplacedCharacters(_ characters: String, by separator: String) -> String {
        let characterSet = CharacterSet(charactersIn: characters)
        return components(separatedBy: characterSet).joined(separator: separator)
    }
}

尝试根据Swift 3的命名约定，提出一个合适的函数名。

这是一个在字符串上的替换方法的扩展，它没有不必要的复制，并在适当的地方做所有事情:

extension String {
    mutating func replaceOccurrences<Target: StringProtocol, Replacement: StringProtocol>(of target: Target, with replacement: Replacement, options: String.CompareOptions = [], locale: Locale? = nil) {
        var range: Range<Index>?
        repeat {
            range = self.range(of: target, options: options, range: range.map { self.index($0.lowerBound, offsetBy: replacement.count)..<self.endIndex }, locale: locale)
            if let range = range {
                self.replaceSubrange(range, with: replacement)
            }
        } while range != nil
    }
}

(方法签名也模仿内置String.replacingOccurrences()方法的签名)

可用于以下方式:

var string = "this is a string"
string.replaceOccurrences(of: " ", with: "_")
print(string) // "this_is_a_string"

Xcode 11•Swift 5.1

StringProtocol replacingOccurrences的突变方法可以实现如下:

extension RangeReplaceableCollection where Self: StringProtocol {
    mutating func replaceOccurrences<Target: StringProtocol, Replacement: StringProtocol>(of target: Target, with replacement: Replacement, options: String.CompareOptions = [], range searchRange: Range<String.Index>? = nil) {
        self = .init(replacingOccurrences(of: target, with: replacement, options: options, range: searchRange))
    }
}

var name = "This is my string"
name.replaceOccurrences(of: " ", with: "+")
print(name) // "This+is+my+string\n"

我实现了这个非常简单的func:

func convap (text : String) -> String {
    return text.stringByReplacingOccurrencesOfString("'", withString: "''")
}

所以你可以这样写:

let sqlQuery = "INSERT INTO myTable (Field1, Field2) VALUES ('\(convap(value1))','\(convap(value2)')

var str = "This is my string"

print(str.replacingOccurrences(of: " ", with: "+"))

输出是

This+is+my+string

基于Ramis回答的Swift 3解决方案:

extension String {
    func withReplacedCharacters(_ characters: String, by separator: String) -> String {
        let characterSet = CharacterSet(charactersIn: characters)
        return components(separatedBy: characterSet).joined(separator: separator)
    }
}

尝试根据Swift 3的命名约定，提出一个合适的函数名。