Convert a JavaScript Regex to a Swift Regex - regex

Question

I'm learning Swift, and I'm trying to convert a small bit of JavaScript code to Swift. The JavaScript code uses a Regex to split up a string, as shown below:
var text = "blah.clah##something_else";
var parts = text.match(/(^.*?)\#\#(.+$)/);
after execution, the parts array will then contain the following:
["blah.clah##something_else", "blah.clah", "something_else"]
I would like to replicate the same behavior in Swift. Below is the Swift code I've written to do split up a String into a String array using a Regex:
func matchesForRegexInText(regex: String!, text: String!) -> [String] {
do {
let regex = try NSRegularExpression(pattern: regex, options: NSRegularExpressionOptions.CaseInsensitive)
let nsString = text as NSString
let results = regex.matchesInString(text,
options: NSMatchingOptions.ReportCompletion , range: NSMakeRange(0, nsString.length))
as [NSTextCheckingResult]
return results.map({
nsString.substringWithRange($0.range)
})
} catch {
print("exception")
return [""]
}
}
When I call the above function with the following:
matchesForRegexInText("(^.*?)\\#\\#(.+$)", text: "blah.clah##something_else")
I get the following:
["blah.clah##something_else"]
I've tried a number of different Regex's without success. Is the Regex (^.*?)\#\#(.+$) correct, or is there a problem with the matchesForRegexInText() function? I appreciate any insight.
I'm using Swift 2, and Xcode Version 7.0 beta (7A120f)

Answer 1

As already mentioned in a comment, your pattern matches the entire
string, so regex.matchesInString() returns a single
NSTextCheckingResult whose range describes the entire string.
What you are looking for are the substrings matching the capture groups
in your pattern. These are available as rangeAtIndex(i) with i >= 1:
func matchesForRegexInText(regex: String!, text: String!) -> [String] {
do {
let regex = try NSRegularExpression(pattern: regex, options: [])
let nsString = text as NSString
guard let result = regex.firstMatchInString(text, options: [], range: NSMakeRange(0, nsString.length)) else {
return [] // pattern does not match the string
}
return (1 ..< result.numberOfRanges).map {
nsString.substringWithRange(result.rangeAtIndex($0))
}
} catch let error as NSError {
print("invalid regex: \(error.localizedDescription)")
return []
}
}
Example:
let matches = matchesForRegexInText("(^.*?)##(.+$)", text: "blah.clah##something_else")
print(matches)
// [blah.clah, something_else]