Programmatically formatting string in swift

Question

I have strings

var arrayWithStrings = ["813 - Crying Flute.mp3", "Ark Patrol - Never.mp3"]

I want to get

var stringTitle1 = "813"
var stringNameOfTrack1 = "CryingFlute"
var stringFormat1 = "mp3"
var stringTitle2 = "Ark Patrol"
var stringNameOfTrack2 = "Never"
var stringFormat2 = "mp3"

How to do it programmatically?

You can use Regular Expression to match every element in the array as you want. — Vkt0r
– Vkt0r, Commented Apr 12, 2015 at 17:57

Rob · Accepted Answer · 2018-12-13 19:53:12Z

4

You can use regular expressions:

let string = "813 - Crying Flute.mp3"

let regex = try! NSRegularExpression(pattern: "^(.*) - (.*)\\.(.*)$")

if let match = regex.firstMatch(in: string, range: string.nsRange) {
    let title  = string[match.range(at: 1)]
    let name   = string[match.range(at: 2)]
    let format = string[match.range(at: 3)]
}

Where, in Swift 4:

extension String {

    /// An `NSRange` that represents the full range of the string.

    var nsRange: NSRange {
        return NSRange(startIndex ..< endIndex, in: self)
    }

    /// Substring from `NSRange`
    ///
    /// - Parameter nsRange: `NSRange` within the string.
    /// - Returns: `Substring` with the given `NSRange`, or `nil` if the range can't be converted.

    subscript(nsRange: NSRange) -> Substring? {
        return Range(nsRange, in: self)
            .flatMap { self[$0] }
    }
}

The regular expression's ( and ) are "capturing parentheses" to identify the substrings, that can be identified by range(at:).

edited Dec 13, 2018 at 19:53

answered Apr 12, 2015 at 18:04

Rob

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2 Comments

Vkt0r Over a year ago

@Rob I though you have an error in the pattern , it should be "^(.*) - (.*)\\.(.*)$" because the beginning isn't always a number, it could be letters regarding the array in the question

Rob Over a year ago

Good catch. Thanks. I was just focusing on the first example.

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