removing white spaces at beginning and end of string

问题

I've got a problem with removing whitespaces at the beginning and end of string. For e.g. I've got a string like:

\r\n\t- Someone will come here?\n- I don't know for sure...\r\n\r\n

And I need to remove whitespaces only at the end and beginning (string should be look like: - Someone will come here?\n- I don't know for sure... Also there could be a lot of variants of string end: "\r\n\r\n", "\r\n", "\n\r\n" and so on...

Thanks.

回答1:

Your string contains not only whitespace but also new line characters.

Use stringByTrimmingCharactersInSet with whitespaceAndNewlineCharacterSet.

let string = "\r\n\t- Someone will come here?\n- I don't know for sure...\r\n\r\n"
let trimmedString = string.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())

In Swift 3 it's more cleaned up:

let trimmedString = string.trimmingCharacters(in: .whitespacesAndNewlines)

回答2:

//here i have used regular expression and replaced white spaces at the start and end
      let stringPassing : NSString? = "hdfjkhsdj hfjksdhf sdf "
      do {
        print("old->\(stringPassing)")
        let pattern : String = "(^\\s+)|(\\s+)$"
        let regex = try NSRegularExpression(pattern: pattern , options: [])
        let newMatched = regex.matchesInString(stringPassing! as String, options: [], range: NSMakeRange(0,stringPassing!.length))
        if(newMatched.count > 0){

          let modifiedString = regex.stringByReplacingMatchesInString(stringPassing! as String, options: [] , range: NSMakeRange(0,stringPassing!.length), withTemplate: "")
              print("new->\(modifiedString)")
        }

    } catch let error as NSError {
        print(error.localizedDescription)
    }

回答3:

String trimming first and last whitespaces and newlines in Swift 4+

"  2 space  ".trimmingCharacters(in: .whitespacesAndNewlines)

result: "2 space"

回答4:

You can use this extension and just call "yourString".trim()

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

回答5:

In this code to restrict Textfield beginning white space

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        if (textField.text?.count)! == 0 && string == " " {
            return false
        }
        else{
            return true
        }
    }

回答6:

In Swift 4 Use it on any String type variable.

extension String {
    func trimWhiteSpaces() -> String {
        let whiteSpaceSet = NSCharacterSet.whitespaces
        return self.trimmingCharacters(in: whiteSpaceSet)
    }
}

And Call it like this

yourString.trimWhiteSpaces()

回答7:

You could first remove from the beginning and then from the end like so:

while true {
if sentence.characters.first == "\r\n" || sentence.characters.first == "\n" {
    sentence.removeAtIndex(sentence.startIndex)
} else {
    break
}
}

while true {
if sentence.characters.last == "\r\n" || sentence.characters.last == "\n" {
    sentence.removeAtIndex(sentence.endIndex.predecessor())
} else {
    break
}
}