Swift String Extension for accessing Characters via Int; plus conversion to C

String+AE.swift

//
//  String+AE.swift
//  Aepryus
//
//  Created by Joe Charlier on 11/20/17.
//  Copyright © 2017 Aepryus Software. All rights reserved.
//

import Foundation

public extension String {
	public subscript(i: Int) -> Character {                              // [a]
		return self[index(startIndex, offsetBy: i)]
	}
	public subscript(r: CountableClosedRange<Int>) -> String {           // [a...b]
		let start = index(startIndex, offsetBy: r.lowerBound)
		let end = index(startIndex, offsetBy: r.upperBound)
		return String(self[start...end])
	}
	public subscript(r: CountablePartialRangeFrom<Int>) -> String {      // [a...]
		let start = index(startIndex, offsetBy: r.lowerBound)
		let end = endIndex
		return String(self[start..<end])
	}
	public subscript(r: PartialRangeThrough<Int>) -> String {            // [...b]
		let start = startIndex
		let end = index(startIndex, offsetBy: r.upperBound)
		return String(self[start...end])
	}
	public subscript(r: PartialRangeUpTo<Int>) -> String {               // [..<b]
		guard r.upperBound > 0 else {return ""}
		let start = startIndex
		let end = index(startIndex, offsetBy: r.upperBound-1)
		return String(self[start...end])
	}
	public func loc(of string: String) -> Int? {
		for i: Int in 0..<count-string.count {
			let test: String = self[i...(i+string.count-1)]
			if string == test {
				return i
			}
		}
		return nil
	}
	public var capitalize: String {
		guard let first = first else { return "" }
		return String(first).uppercased() + dropFirst()
	}

	public func toInt8() -> UnsafeMutablePointer<Int8> {
		return UnsafeMutablePointer<Int8>(mutating: (self as NSString).utf8String!)
	}
	public func toCString() -> [CChar]? {
		return self.cString(using: .utf8)
	}
	public static func uuid() -> String {
		return UUID().uuidString
	}
}