Split String with more than one character in Swift

Question

I've read the other threads but they only seem to deal with single character delimiters, and I think Playground is crashing for me because I use more than one char.

"[0, 1, 2, 1]".characters
              .split(isSeparator: {[",", "[", "]"].contains($0)}))
              .map(String.init) //["0", " 1", " 2", " 1"]

kinda works but I want to use " ," not ",". Obviously I can use [",", " ", "[", "]"] and that throws out the spaces but what about when I want only string patterns to be removed?

In brief: How do I separate a Swift string by precisely other smaller string(s)?

Answer 1

Swift 3

let s = "[0, 1, 2, 1]"
let splitted = s.characters.split { [",", "[", "]"].contains(String($0)) }
let trimmed = splitted.map { String($0).trimmingCharacters(in: .whitespaces) }

Swift 2

let s = "[0, 1, 2, 1]"
let charset = NSCharacterSet.whitespaceCharacterSet()
let splitted = s.characters.split(isSeparator: {[",", "[", "]"].contains($0)})
let trimmed = splitted.map { String($0).stringByTrimmingCharactersInSet(charset) }

Result is an array of Strings without the extra spaces:

["0", "1", "2", "1"]

Answer 2

A couple of possibilities spring to mind. If you can use characters as separators:

let str = "[0, 1, 2, 1]"
let separatorSet = NSCharacterSet(charactersInString: ",[]")
let comps = str.componentsSeparatedByCharactersInSet(separatorSet).filter({return !$0.isEmpty})

This yields

["0", " 1", " 2", "1"]

If necessary, the spaces can be removed by either mapping with stringByTrimmingCharactersInSet or by adding a space to the separatorSet.

Or if you really need to use strings as separators:

let str = "[0, 1, 2, 1]"
let separators = [", ", "[", "]"]
let comps = separators.reduce([str]) { (comps, separator) in
    return comps.flatMap { return $0.componentsSeparatedByString(separator) }.filter({return !$0.isEmpty})
}

Which yields:

["0", "1", "2", "1"]