Replace sequence of spaces in string with a single character in swift

Question

I want to replace a series of spaces from a string with an underscore. For example

"This       is     a string with a lot of spaces!"

should become

"This_is_a_string_with_a_lot_of_spaces!"

How to do this?

score 12 · Accepted Answer · answered Apr 01 '16 at 18:43

12

Alternative non-regex solution:

let foo = "This       is     a string with a lot of spaces!"
let bar = foo
    .componentsSeparatedByString(" ")
    .filter { !$0.isEmpty }
    .joinWithSeparator("_")

print(bar) /* This_is_a_string_with_a_lot_of_spaces! */

Works also for unicode characters (thanks @MartinR for this beautiful example)

let foo = "       "

// ...

/* _____ */

answered Apr 01 '16 at 18:43

dfrib

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That's a pretty slick use of Filter. – Nate Birkholz Apr 01 '16 at 18:46
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@NateBirkholz I should point out, however, that this method above will not replace groups of spaces prior and after the first and last words, respectively; these spaces will just be removed (e.g. `" This is a string with a lot of spaces! "` will yield the same result as for `"This is a string with a lot of spaces!"`). – dfrib Apr 01 '16 at 18:50
That is exactly what I need, so that won't be a problem – sloeberGJ Apr 02 '16 at 12:24

Martin R · Answer 2 · 2016-04-01T18:54:16.060

5

@remus suggestion can be simplified (and made Unicode/Emoji/Flag-safe) as

let myString = "  This       is     a string with a lot of spaces!         "
let replacement = myString.stringByReplacingOccurrencesOfString("\\s+", withString: "_", options: .RegularExpressionSearch)
print(replacement)
// _This_is_a_string_with_a_lot_of_spaces!____

edited Apr 01 '16 at 18:54

answered Apr 01 '16 at 18:47

Martin R

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brandonscript · Answer 3 · 2016-04-01T19:14:12.603

3

You can use a simple regular expression replacement to do this:

let myString = "     "
if let regex = try? NSRegularExpression(pattern: "\\s+", options: []) {
    let replacement = regex.stringByReplacingMatchesInString(myString, options: .WithTransparentBounds, range: NSMakeRange(0, (myString as NSString).length), withTemplate: "_")
    print(replacement)
    // "_____"
}

edited Apr 01 '16 at 19:14

answered Apr 01 '16 at 18:35

brandonscript

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Test your code with the `let myString = " "` ... :) – Martin R Apr 01 '16 at 18:43
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WHHHYYYYY UNICODE WHYYYY – brandonscript Apr 01 '16 at 18:44

score 1 · Answer 4 · 2016-04-01T20:22:11.537

Alternative non-regex, pure Swift (no bridging to NSString) solution:

let spaced = "This       is     a string with a lot of spaces!"

let under = spaced.characters.split(" ", allowEmptySlices: false).map(String.init).joinWithSeparator("_")

Alternate, alternate version that doesn't remove leading and trailing spaces when converting. Slightly obfuscated for brevity... ;-)

let reduced = String(spaced.characters.reduce([Character]()) { let n = $1 == " " ? "_" : $1; var o = $0; o.append(n); guard let e = $0.last else { return o }; return e == "_" && n == "_" ? $0 : o })

There's probably a more clever solution involving flatMap() but I'll leave it to someone more clever than I!

Just note that as in @dfris' solution, this will remove and not replace initial and trailing spaces. — Martin R, Apr 01 '16 at 18:53

Replace sequence of spaces in string with a single character in swift

4 Answers4