Super CollectionView/TableView nib loading with protocols and generics.

CollectionViewMagic.swift

//
//  CollectionViewMagic.swift
//  bodytonic-ios
//
//  Created by Desmond McNamee on 2016-10-29.
//  Copyright © 2016 Stadium Studio. All rights reserved.
//

import UIKit

protocol ReusableView: class {
    static var reuseIdentifier: String { get }
}

extension ReusableView where Self: UIView {
    static var reuseIdentifier: String {
        return String(describing: self)
    }
}

protocol NibLoadableView: class {
    static var nibName: String { get }
}

extension NibLoadableView where Self: UIView {
    static var nibName: String {
        return String(describing: self)
    }
}

extension UITableView {
    func register<T: UITableViewCell>(_: T.Type) where T: ReusableView, T: NibLoadableView {
        self.register(UINib(nibName: T.nibName, bundle: nil), forCellReuseIdentifier: T.reuseIdentifier)
    }
    
    func dequeueReusableCell<T: UITableViewCell>(forIndexPath indexPath: IndexPath) -> T where T: ReusableView {
        guard let cell = self.dequeueReusableCell(withIdentifier: T.reuseIdentifier) as? T else {
            fatalError("Could not dequeue cell with identifier: \(T.reuseIdentifier)")
        }
        
        return cell
    }
}

extension UICollectionView {
    
    func register<T: UICollectionViewCell>(_: T.Type) where T: ReusableView {
        register(T.self, forCellWithReuseIdentifier: T.reuseIdentifier)
    }
    
    func register<T: UICollectionViewCell>(_: T.Type) where T: ReusableView, T: NibLoadableView {
        let bundle = Bundle(for: T.self)
        let nib = UINib(nibName: T.nibName, bundle: bundle)
        
        register(nib, forCellWithReuseIdentifier: T.reuseIdentifier)
    }
    
    func dequeueReusableCell<T: UICollectionViewCell>(forIndexPath indexPath: IndexPath) -> T where T: ReusableView {
        guard let cell = dequeueReusableCell(withReuseIdentifier: T.reuseIdentifier, for: indexPath as IndexPath) as? T else {
            fatalError("Could not dequeue cell with identifier: \(T.reuseIdentifier)")
        }
        
        return cell
    }
}