Extension for UITableView, UITableViewCell, UICollectionView, UICollectionViewCell.

TableCollectionUtils.swift

//
//  TableCollectionUtils.swift
//
//  Created by Kalpesh on 25/05/18.
//  Copyright © 2018 Kalpesh Talkar. All rights reserved.
//
//  Support: https://gist.github.com/KalpeshTalkar/aaa6d41bb6b0b10a8ceb2b8cd8c1b791
//  GitHub: https://github.com/KalpeshTalkar
//  Gists: https://gist.github.com/KalpeshTalkar
//

import UIKit


/// Protocol thet provides identfier for reusing UICollectionViewCells and UITableViewCells
public protocol ReuseIdentifying {
    
    /// Reuse identifier
    static var reuseIdentifier: String { get }
    
}


// MARK: - Extension for ReuseIdentifying
public extension ReuseIdentifying {
    
    /// Reuse identifier implementation. This will return a string of the class name.
    public static var reuseIdentifier: String {
        return String(describing: self)
    }
    
}


// MARK: - UICollectionViewCell extension conforming to ReuseIdentifying
extension UICollectionViewCell: ReuseIdentifying {}


// MARK: - UITableViewCell extension conforming to ReuseIdentifying
extension UITableViewCell: ReuseIdentifying {}


// MARK: - UICollectionView extension
public extension UICollectionView {
    
    
    // MARK: - Reusable Cell
    
    
    /// Returns a reusable cell object located by its identifier.
    ///
    /// - Parameters:
    ///   - indexPath: The index path specifying the location of the cell.
    ///   - type: The class of your custom collection view cell.
    /// - Returns: A valid UICollectionReusableView object.
    public func dequeueReusableCell<T: UICollectionViewCell>(for indexPath: IndexPath, ofType type: T.Type) -> T? {
        return dequeueReusableCell(withReuseIdentifier: T.reuseIdentifier, for: indexPath) as? T
    }
    
    
    // MARK: - Empty States
    
    
    /// Shows empty view if the collection view has no data.
    ///
    /// - Parameter emptyView: view to be shown as empty state.
    public func showEmptyStateIfNeeded(emptyView: UIView?) {
        var collectionHasData = false
        let sections = numberOfSections
        for i in 0..<sections {
            let itemsInSec = numberOfItems(inSection: i)
            if itemsInSec > 0 {
                collectionHasData = true
                break
            }
        }

        if refreshControl != nil {
            // Enable scroll if refresh control is set
            isScrollEnabled = true
        } else {
            // Enable scroll if not empty
            isScrollEnabled = collectionHasData
        }

        if !collectionHasData {
            emptyView?.frame = frame
            backgroundView = emptyView
        } else {
            backgroundView = UIView()
        }
    }
    
}


// MARK: - UITableView extension
public extension UITableView {
    
    
    // MARK: - Reusable Cell
    
    
    /// Returns a reusable table-view cell object located by its identifier.
    ///
    /// - Parameter type: The class of your custom tableview cell.
    /// - Returns: A UITableViewCell object with the associated identifier or nil if no such object exists in the reusable-cell queue.
    public func dequeueReusableCell<T: UITableViewCell>(ofType type: T.Type) -> T? {
        return dequeueReusableCell(withIdentifier: T.reuseIdentifier) as? T
    }
    
    
    /// Returns a reusable table-view cell object for the specified reuse identifier and adds it to the table.
    ///
    /// - Parameters:
    ///   - indexPath: The index path specifying the location of the cell.
    ///   - type: The class of your custom tableview cell.
    /// - Returns: A UITableViewCell object with the associated reuse identifier. This method always returns a valid cell.
    public func dequeueReusableCell<T: UITableViewCell>(for indexPath: IndexPath, ofType type: T.Type) -> T? {
        return dequeueReusableCell(withIdentifier: T.reuseIdentifier, for: indexPath) as? T
    }
    
    
    // MARK: - Empty States
    
    
    /// Shows empty view if the collection view has no data.
    ///
    /// - Parameter emptyView: view to be shown as empty state.
    public func showEmptyStateIfNeeded(emptyView: UIView?) {
        var tableHasData = false
        let sections = numberOfSections
        for i in 0..<sections {
            let rowsInSec = numberOfRows(inSection: i)
            if rowsInSec > 0 {
                tableHasData = true
                break
            }
        }

        if refreshControl != nil {
            // Enable scroll if refresh control is set
            isScrollEnabled = true
        } else {
            // Enable scroll if not empty
            isScrollEnabled = tableHasData
        }

        if !tableHasData {
            emptyView?.frame = frame
            backgroundView = emptyView
        } else {
            backgroundView = UIView()
        }
    }
    
}