swift对String有修饰方法吗？

Question

swift对String有修饰方法吗？例如:

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

Answer 1

以下是从a的开头和结尾删除所有空格的方法String.

(使用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"

(使用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"

希望这可以帮助.

Answer 2

将此代码放在项目的文件中,类似于Utils.swift:

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

所以你将能够做到这一点:

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

Swift 3.0解决方案

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

所以你将能够做到这一点:

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

Answer 3

在Swift 3.0中

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

你可以打电话

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

Answer 4

Swift 4.2

let trimmedString = " abc ".trimmingCharacters(in: .whitespaces)
 //trimmedString == "abc"

Answer 5

斯威夫特3

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

Answer 6

是的,你可以这样做:

var str = "  this is the answer   "
str = str.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
print(srt) // "this is the answer"

CharacterSet实际上是一个非常强大的工具,可以创建一个比.whitespacesAndNewlines之类的预定义集更灵活的修剪规则.

例如:

var str = " Hello World !"
let cs = CharacterSet.init(charactersIn: " !")
str = str.trimmingCharacters(in: cs)
print(str) // "Hello World"

Answer 7

将字符串截断为特定长度

如果您输入了句子/文本块,并且只想保存指定长度的文本.将以下扩展添加到Class

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)
   }

}

使用

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 

Answer 8

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

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

Answer 9

另一种类似方式:

extension String {
    var trimmed:String {
        return self.trimmingCharacters(in: CharacterSet.whitespaces)
    }
}

使用:

let trimmedString = "myString ".trimmed

Answer 10

//Swift 4.0 删除空格和换行

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