Swift Replace Multiple Characters in String

Question

Below is the following line of code I use to replace an HTML break tag with a carriage return. However, I have other HTML symbols that I need to replace and when I call this line of code again, with different parameters, it's as if the first one is overwritten. Is there a way I can include multiple parameters? Is there a more efficient way to do this in Swift? For example: replace both br> with "" and nbsp with "".

textView.text = content.stringByReplacingOccurrencesOfString("<br /><br />", withString:"\r")

Show how you "call this line of code again". That's where you're going wrong, after all. — matt
– matt, Commented Jan 21, 2015 at 4:23
textView.text = content.stringByReplacingOccurrencesOfString("<br /><br />", withString:"\r") textView.text = content.stringByReplacingOccurrencesOfString(" ", withString:" ") — Jeff Richard
– Jeff Richard, Commented Jan 21, 2015 at 4:27
But there's the problem. You are starting over from the original content. The text view's text is overwritten because you are overwriting it! — matt
– matt, Commented Jan 21, 2015 at 4:45
@matt I understood this question to be asking if there's a way of replacing all the characters you want in one pass. i.e. textView.text = content.stringByReplacingOccurrencesOfString([",", ":", "\n", "\r"], withString "") — Declan McKenna
– Declan McKenna, Commented Feb 12, 2016 at 16:02

Aark · Accepted Answer · 2017-05-17 13:57:46Z

35

Use replacingOccurrences along with a the String.CompareOptions.regularExpresion option.

Example (Swift 3):

var x = "<Hello, [play^ground+]>"
let y = x.replacingOccurrences(of: "[\\[\\]^+<>]", with: "7", options: .regularExpression, range: nil)
print(y)

Input characters which are to be replaced inside the square brackets like so [\\ Characters]

Output:

7Hello, 7play7ground777

edited May 17, 2017 at 13:57

Aark

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answered Nov 10, 2016 at 15:34

Michael Peterson

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3 Comments

Trev14 Over a year ago

This is great & exactly what I was looking for! Great use of RegEx, something I haven't used much in Swift. Thanks for the awesome answer Michael.

Vyachaslav Gerchicov Over a year ago

Could you explain - should I always use .regularExpression? What if I just need to specify a list of concrete symbols I need to replace/delete?

Michael Peterson Over a year ago

There may be other ways, however a regular expression is good way to represent a set of concrete characters. For example if I wanted to replace "A", "B", and "Z", the code would look like: x.replacingOccurrences(of: "[ABZ]", with: "7", options: .regularExpression, range: nil)

bennyty · Accepted Answer · 2016-07-21 16:41:12Z

13

I solved it based on the idea of Rosetta Code

extension String {
    func stringByRemovingAll(characters: [Character]) -> String {
        return String(self.characters.filter({ !characters.contains($0) }))
    }

    func stringByRemovingAll(subStrings: [String]) -> String {
        var resultString = self
        subStrings.map { resultString = resultString.stringByReplacingOccurrencesOfString($0, withString: "") }
        return resultString
    }
}

Example:

let str = "Hello, stackoverflow"
let chars: [Character] = ["a", "e", "i"]
let myStrings = ["Hello", ", ", "overflow"]

let newString = str.stringByRemovingAll(chars)
let anotherString = str.stringByRemovingAll(myStrings)

Result, when printed:

newString: Hllo, stckovrflow

anotherString: stack

edited Jul 21, 2016 at 16:41

bennyty

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answered Feb 17, 2016 at 17:20

skofgar

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3 Comments

Michael Peterson Over a year ago

This is not an efficient solution, see my answer using CompareOptions.CompareOptions.regularExpression

Karthik Kannan Over a year ago

@Michael But I guess this works in more generic cases. What if my strings aren't regular expressions? How would your answer change?

Michael Peterson Over a year ago

@KarthikKannan Are you referring to my answer below? Did you comment in the wrong answer? If so, please repeat the question in my answer to avoid confusion for others.

Jawwad · Accepted Answer · 2015-01-21 05:22:46Z

8

As @matt mentioned you are starting over with the same content string. The stringByReplacingOccurrencesOfString method doesn't actually change anything in the original content string. It returns to you a new string with the replacement changes while content remains unchanged.

Something like this should work for you

let result1 = content.stringByReplacingOccurrencesOfString("<br /><br />", withString:"\r") 
let result2 = result1.stringByReplacingOccurrencesOfString(" &nbsp;", withString:" ")
textView.text = result2

answered Jan 21, 2015 at 5:22

Jawwad

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Comments

Leo Dabus · Accepted Answer · 2015-01-21 09:41:15Z

1

extension String {
    var html2AttributedString:NSAttributedString {
        return NSAttributedString(data: dataUsingEncoding(NSUTF8StringEncoding)!, options:[NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType, NSCharacterEncodingDocumentAttribute: NSUTF8StringEncoding], documentAttributes: nil, error: nil)!
    }
}

let myHtmlCode = "<style type=\"text/css\">#red{color:#F00}#green{color:#0F0}#blue{color: #00F}</style><span id=\"red\" >Red</span> <span id=\"green\" >Green</span><span id=\"blue\">Blue</span>"

myHtmlCode.html2AttributedString

answered Jan 21, 2015 at 9:41

Leo Dabus

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