我创建了这个函数，允许输入字符串并返回由任意字符修剪的字符串列表

 func Trim(input:String, character:Character)-> [String]
{
    var collection:[String] = [String]()
    var index  = 0
    var copy = input
    let iterable = input
    var trim = input.startIndex.advancedBy(index)

    for i in iterable.characters

    {
        if (i == character)
        {

            trim = input.startIndex.advancedBy(index)
            // apennding to the list
            collection.append(copy.substringToIndex(trim))

            //cut the input
            index += 1
            trim = input.startIndex.advancedBy(index)
            copy = copy.substringFromIndex(trim)

            index = 0
        }
        else
        {
            index += 1
        }
    }
    collection.append(copy)
    return collection

}

As在swift中没有找到这样做的方法(在swift 2.0中编译和工作完美)

下面介绍如何从字符串的开头和结尾删除所有空白。

(用Swift 2.0测试的示例。)

let myString = "  \t\t  Let's trim all the whitespace  \n \t  \n  "
let trimmedString = myString.stringByTrimmingCharactersInSet(
    NSCharacterSet.whitespaceAndNewlineCharacterSet()
)
// Returns "Let's trim all the whitespace"

(用Swift 3+测试的示例。)

let myString = "  \t\t  Let's trim all the whitespace  \n \t  \n  "
let trimmedString = myString.trimmingCharacters(in: .whitespacesAndNewlines)
// Returns "Let's trim all the whitespace"

**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"

斯威夫特3

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

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)

将字符串截断为特定长度

如果你已经输入了一段句子/文本，你想只保存指定长度的文本。将以下扩展添加到类中

extension String {

   func trunc(_ length: Int) -> String {
    if self.characters.count > length {
        return self.substring(to: self.characters.index(self.startIndex, offsetBy: length))
    } else {
        return self
    }
  }

  func trim() -> String{
     return self.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
   }

}

Use

var str = "Lorem Ipsum is simply dummy text of the printing and typesetting industry."
//str is length 74
print(str)
//O/P:  Lorem Ipsum is simply dummy text of the printing and typesetting industry.

str = str.trunc(40)
print(str)
//O/P: Lorem Ipsum is simply dummy text of the