ListFormatting.swift

/*
    Copyright (C) 2016 Apple Inc. All Rights Reserved.
    See LICENSE.txt for this sample’s licensing information
    
    Abstract:
    The `ListFormatting` class has two purposes: one for transforming `ListItem` objects into a string representation, and one for transforming a string representation of a list into a `ListItem` array. It is used for copying and pasting `ListItem` objects into and out of the app via `NSPasteboard`.
*/

import Foundation

public class ListFormatting {
    /// Construct a `ListItem` array from a string.
    public class func listItemsFromString(string: String) -> [ListItem] {
        var listItems = [ListItem]()

        let enumerationOptions: NSStringEnumerationOptions = [.BySentences, .ByLines]
        let range = string.startIndex..<string.endIndex

        let characterSet = NSCharacterSet.whitespaceAndNewlineCharacterSet()

        string.enumerateSubstringsInRange(range, options: enumerationOptions) { substring, _, _, _ in
            let trimmedString = substring!.stringByTrimmingCharactersInSet(characterSet)

            if !trimmedString.isEmpty {
                let item = ListItem(text: trimmedString)

                listItems += [item]
            }
        }

        return listItems
    }

    /// Concatenate all item's `text` property together.
    public class func stringFromListItems(items: [ListItem]) -> String {
        return items.reduce("") { string, item in
            "\(string)\(item.text)\n"
        }
    }
}