Splitting a Swift String using a multi-Character String in Swift 2 - ios

Question

I understand that I can fallback to the NSString function componentsSeparatedByString, and so perhaps this is a nitpick, but one of the things I like about Swift is that it is designed around brevity and short syntax.
I was really hoping I could just: var parts = myString.characters.split("${") but that function only works for a single Character, not a two Character string. I even tried var parts = myString.characters.split { $0 == "${" } but that is expecting a single Character as the delimiter and not a full String. :(
Is there an api function that I'm missing or do I need to stick with the the old NSString bridged functions?

Answer 1

Here's a rather simple-minded approach that makes it possible to use Swift split on a single character:
extension String {
mutating func replace(target:String, with:String) {
while let r = self.rangeOfString(target) {
self.replaceRange(r, with: with)
}
}
func split(separator:String) -> Array<String> {
var s = self
s.replace(separator, with:"☞") // arbitrary improbable character :)
return s.characters.split("☞").map{String($0)}
}
}
var s = "the${cat${sat${on${the${mat"
let arr = s.split("${")
However, rangeOfString is actually a Foundation method on NSString; if you don't import Foundation (or UIKit), that code won't compile. So in reality it's no improvement over just calling componentsSeparatedByString. I don't actually understand your objection to it in the first place; Swift has holes exactly because it expects Foundation to be backing it up and filling those holes.

Answer 2

'pure' Swift's solution where import Foundation is NOT required and arbitrary improbable character doesn't exists
let str = "t{he${cat${sat${on${the${mat"
let splitBy = "${"
extension String {
func split(splitBy: String)->[String] {
if self.isEmpty { return [] }
var arr:[String] = []
var tmp = self
var tmp1 = ""
var i = self.startIndex
let e = self.endIndex
let c = splitBy.characters.count
while i < e {
let tag = tmp.hasPrefix(splitBy)
if !tag {
tmp1.append(tmp.removeAtIndex(tmp.startIndex))
i = i.successor()
} else {
tmp.removeRange(Range(start: tmp.startIndex, end: tmp.startIndex.advancedBy(c)))
i = i.advancedBy(c)
arr.append(tmp1)
tmp1 = ""
}
}
arr.append(tmp1)
return arr.filter{ !$0.isEmpty }
}
}
let arr = str.split(splitBy) // ["t{he", "cat", "sat", "on", "the", "mat"]

Answer 3

If you have Foundation imported, you can use the components(separatedBy:) method to accomplish that.
let str = "Foo, Bar, Baz"
str.components(separatedBy: ", ")
Here are the docs.
(Tested on Ubuntu Linux)