Swift - iOS: Remove spaces inside a String before or after any special character

Question

I have to do validation to check user entered answer to an application. I want to remove spaces (if any) left or before for bellow special characters.

• /
• ,
• :
• ;
• -
• .

So the final output should be like this.

Ex:

Correct answer => a/b

Answers need to accept => ' a/b ', 'a/ b', 'a /b', 'a/ b ', 'a/b '

I can do this using replacingOccurrences function by replacing all possible values. Is there any better solution for this?

Answer 1

Remove before and after space of Special character using Range -

    let specialChars = ["/",":", ",", ";", "-", "."]
    let aString = " AB / CD EF ; G : H , MN O - P"
    var trimmedString = aString.trimmingCharacters(in: .whitespacesAndNewlines)

    for specialChar in specialChars {

        if let beforeSpacerange = trimmedString.range(of: " \(specialChar)") {
            trimmedString.replaceSubrange(beforeSpacerange, with: specialChar)
        }
        if let afterSpacerange = trimmedString.range(of: "\(specialChar) ") {
            trimmedString.replaceSubrange(afterSpacerange, with: specialChar)
        }

    }

    debugPrint(trimmedString)

Hope it will help you. Let me know if you are still having any issue.

Happy coding.

Answer 2

You can using regular expression for replace the string with format [ ]+{special_char} and {special_char}[ ]+ .

Edit

Update "." to "\\\\."

Thanks ielyamani

For example

func acceptedAnswer(of answer: String) -> String {
    let specialChars = ["/", ":", ",", ";", "-", "\\."]
    var newAnswer = answer.trimmingCharacters(in: .whitespacesAndNewlines)
    for specialChar in specialChars {
        let beforeCharRegex = "[ ]+" + specialChar
        let afterCharRegex = specialChar + "[ ]+"
        newAnswer = newAnswer.replacingOccurrences(of: beforeCharRegex, with: specialChar, options: .regularExpression, range: nil)
        newAnswer = newAnswer.replacingOccurrences(of: afterCharRegex, with: specialChar, options: .regularExpression, range: nil)
    }
    return newAnswer
}

print(acceptedAnswer(of: " apple /   orange     : banana    "))
// apple/orange:banana

Answer 3

You can use replacingOccurrences which would replace your symbol with whitespaces with just this symbol. For this purpose you can use recursive method

func removed(in text: String) -> String {
    let symbols = ["/", ",", ":", ";", "-", "."]
    var newText = text
    symbols.forEach { newText = replaced(in: newText, for: $0) }
    return newText
}

func replaced(in text: String, for symbol: String) -> String {
    var newText = text
    let left = " \(symbol)"
    newText = newText.replacingOccurrences(of: left, with: symbol)
    let right = "\(symbol) "
    newText = newText.replacingOccurrences(of: right, with: symbol)
    return newText != text ? replaced(in: newText, for: symbol) : newText
}

Usage:

let string = "Apple / Orange Swift    .   ObjC Moon  : Sun USA - UK"
print(removed(in: string))

 Apple/Orange Swift.ObjC Moon:Sun USA-UK