Find characters inside quotation marks in String - swift

Question

I'm trying to pull out the parts of a string that are in quotation marks, i.e. in "Rouge One" is an awesome movie I want to extract Rouge One.
This is what I have so far but can't figure out where to go from here: I create a copy of the text so that I can remove the first quotation mark so that I can get the index of the second.
if text.contains("\"") {
guard let firstQuoteMarkIndex = text.range(of: "\"") else {return}
var textCopy = text
let textWithoutFirstQuoteMark = textCopy.replacingCharacters(in: firstQuoteMarkIndex, with: "")
let secondQuoteMarkIndex = textCopy.range(of: "\"")
let stringBetweenQuotes = text.substring(with: Range(start: firstQuoteMarkIndex, end: secondQuoteMarkIndex))
}

Answer 1

There is no need to create copies or to replace substrings for this task.
Here is a possible approach:
Use text.range(of: "\"") to find the first quotation mark.
Use text.range(of: "\"", range:...) to find the second quotation mark, i.e. the first one after the range found in step 1.
Extract the substring between the two ranges.
Example:
let text = " \"Rouge One\" is an awesome movie"
if let r1 = text.range(of: "\""),
let r2 = text.range(of: "\"", range: r1.upperBound..<text.endIndex) {
let stringBetweenQuotes = text.substring(with: r1.upperBound..<r2.lowerBound)
print(stringBetweenQuotes) // "Rouge One"
}
Another option is a regular expression search with "positive lookbehind" and "positive lookahead" patterns:
if let range = text.range(of: "(?<=\\\").*?(?=\\\")", options: .regularExpression) {
let stringBetweenQuotes = text.substring(with: range)
print(stringBetweenQuotes)
}

Answer 2

var rouge = "\"Rouge One\" is an awesome movie"
var separated = rouge.components(separatedBy: "\"") // ["", "Rouge One", " is an awesome movie"]
separated.dropFirst().first

Answer 3

I would use .components(separatedBy:)
let stringArray = text.components(separatedBy: "\"")
Check if stringArray count is > 2 (there is at least 2 quotes).
Check if stringArray count is odd, aka count % 2 == 1.
If it is odd, all the even indices are between 2 quotes and they are what you want.
If it is even, all the even indices - 1 are between 2 quotes (the last one doesn't have an end quote).
This will allow you to also capture multiple sets of quoted strings, like:
"Rogue One" is a "Star Wars" movie.

Answer 4

Another option is to use regular expressions to find pairs of quotes:
let pattern = try! NSRegularExpression(pattern: "\\\"([^\"]+)\\\"")
// Small helper methods making it easier to work with enumerateMatches(in:...)
extension String {
subscript(utf16Range range: Range<Int>) -> String? {
get {
let start = utf16.index(utf16.startIndex, offsetBy: range.lowerBound)
let end = utf16.index(utf16.startIndex, offsetBy: range.upperBound)
return String(utf16[start..<end])
}
}
var fullUTF16Range: NSRange {
return NSRange(location: 0, length: utf16.count)
}
}
// Loop through *all* quoted substrings in the original string.
let str = "\"Rogue One\" is an awesome movie"
pattern.enumerateMatches(in: str, range: str.fullUTF16Range) { (result, flags, stop) in
// rangeAt(1) is the range representing the characters in the 1st
// capture group of the regular expression: ([^"]+)
if let result = result, let range = result.rangeAt(1).toRange() {
print("This was in quotes: \(str[utf16Range: range] ?? "<bad range>")")
}
}