你也可以使用正则表达式。

let trimmedString = myString.stringByReplacingOccurrencesOfString("\\s", withString: "", options: NSStringCompareOptions.RegularExpressionSearch, range: nil)

这在swift 5中很管用

var myString = " Kwame Ch ef "
myString = myString.replacingOccurrences(of: " ", with: "")
print(myString)

output: Kwame Chef

尝试函数式编程来删除空白:

extension String {
  func whiteSpacesRemoved() -> String {
    return self.filter { $0 != Character(" ") }
  }
}

我会使用这个扩展，以灵活和模仿其他集合如何做到这一点:

extension String {
    func filter(pred: Character -> Bool) -> String {
        var res = String()
        for c in self.characters {
            if pred(c) {
                res.append(c)
            }
        }
        return res
    }
}

"this is a String".filter { $0 != Character(" ") } // "thisisaString"

羽毛球猫的答案的Swift 3版本

extension String {
    func replace(_ string:String, replacement:String) -> String {
        return self.replacingOccurrences(of: string, with: replacement, options: NSString.CompareOptions.literal, range: nil)
    }

    func removeWhitespace() -> String {
        return self.replace(" ", replacement: "")
    }
}

Swift 3版本

  //This function trim only white space:
   func trim() -> String
        {
            return self.trimmingCharacters(in: CharacterSet.whitespaces)
        }
    //This function trim whitespeaces and new line that you enter:
     func trimWhiteSpaceAndNewLine() -> String
        {
            return self.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
        }