Generate random identifiers in the style of Xcode.

IdentifierGenerator.swift

public class IdentifierGenerator {
    
    private let characters = Array("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
    private let separator = "-"
    
    public func generateIdentifier() -> String {
        let numCharacters = UInt32(characters.count)
        func randomCharacter() -> Character {
            let index = Int(arc4random_uniform(numCharacters))
            return characters[index]
        }
        var identifier: String = ""
        identifier.reserveCapacity(3+1+2+1+3)
        for _ in 1...3 { identifier.append(randomCharacter()) }
        identifier += separator
        for _ in 1...2 { identifier.append(randomCharacter()) }
        identifier += separator
        for _ in 1...3 { identifier.append(randomCharacter()) }
        return identifier
    }
    
}