LocalizedIndexedCollation-ViewController.swift

import UIKit

func namedModels() -> [ModelObject] {
    let names: [String] = UIFont.familyNames()
    return names.map(ModelObject.init)
}

class ModelObject: NSObject {
    let name: String
    init(name: String) { self.name = name }
    func displayName() -> String { return self.name }
}


class ViewController: UIViewController, UITableViewDataSource {
    
    static let CellIdentifier = "MyIdentifier"
    
    @IBOutlet var tableView: UITableView!
    var tableData: [[ModelObject]] = []
    let collation = UILocalizedIndexedCollation.currentCollation()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.tableView.dataSource = self
        
        let objects = namedModels()
        self.tableData = self.partitionCollatedObjects(objects, collationStringSelector: #selector(ModelObject.displayName))
    }
    
    private func partitionCollatedObjects<T where T: AnyObject>(objects: [T], collationStringSelector: Selector) -> [[T]] {
        var sections: [[T]] = Array(count: collation.sectionTitles.count, repeatedValue: [T]())
        let sortedObjects = collation.sortedArrayFromArray(objects, collationStringSelector: collationStringSelector) as! [T]
        
        for object in sortedObjects {
            let index = collation.sectionForObject(object, collationStringSelector: collationStringSelector)
            sections[index].append(object)
        }
        
        return sections
    }

    // MARK: UITableViewDataSource
    func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return self.collation.sectionTitles.count
    }
    
    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.tableData[section].count
    }
    
    func sectionIndexTitlesForTableView(tableView: UITableView) -> [String]? {
        return collation.sectionIndexTitles
    }
    
    func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        let showSection = self.tableData[section].count != 0
        return showSection ? self.collation.sectionTitles[section] : nil
    }
    
    func tableView(tableView: UITableView, sectionForSectionIndexTitle title: String, atIndex index: Int) -> Int {
        return self.collation.sectionForSectionIndexTitleAtIndex(index)
    }
    
    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier(ViewController.CellIdentifier)!
        let model = self.tableData[indexPath.section][indexPath.row]
        
        // configure cell
        cell.textLabel?.text = model.displayName()
        
        return cell
    }
}