斯威夫特3

let result = " abc ".trimmingCharacters(in: .whitespacesAndNewlines)

**Swift 5**

extension String {

    func trimAllSpace() -> String {
         return components(separatedBy: .whitespacesAndNewlines).joined()
    }
    
    func trimSpace() -> String {
        return self.trimmingCharacters(in: .whitespacesAndNewlines)
    }
}

**Use:**
let result = " abc ".trimAllSpace()
// result == "abc"
let ex = " abc cd  ".trimSpace()
// ex == "abc cd"

您还可以发送您想要修剪的字符

extension String {


    func trim() -> String {

        return self.trimmingCharacters(in: .whitespacesAndNewlines)

    }

    func trim(characterSet:CharacterSet) -> String {

        return self.trimmingCharacters(in: characterSet)

    }
}

validationMessage = validationMessage.trim(characterSet: CharacterSet(charactersIn: ","))

不要忘记导入Foundation或UIKit。

import Foundation
let trimmedString = "   aaa  "".trimmingCharacters(in: .whitespaces)
print(trimmedString)

结果:

"aaa"

否则你会得到:

error: value of type 'String' has no member 'trimmingCharacters'
    return self.trimmingCharacters(in: .whitespaces)

你可以在我写的Swift String扩展https://bit.ly/JString中使用trim()方法。

var string = "hello  "
var trimmed = string.trim()
println(trimmed)// "hello"

把这段代码放在你项目的一个文件中，比如Utils.swift:

extension String {   
    func trim() -> String {
        return self.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
    }
}

所以你可以这样做:

let result = " abc ".trim()
// result == "abc"

Swift 3.0解决方案

extension String {   
    func trim() -> String {
    return self.trimmingCharacters(in: NSCharacterSet.whitespaces)
   }
}

所以你可以这样做:

let result = " Hello World ".trim()
// result = "HelloWorld"