SPDiffableSideBarController.swift

// The MIT License (MIT)
// Copyright © 2020 Ivan Vorobei (hello@ivanvorobei.io)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#if canImport(UIKit) && os(iOS)
import UIKit

@available(iOS 14, *)
open class SPDiffableSideBarController: SPDiffableCollectionController {
    
    // MARK: - Init
    
    public init() {
        super.init(collectionViewLayout: UICollectionViewFlowLayout())
        commonInit()
    }
    
    public required init?(coder: NSCoder) {
        super.init(coder: coder)
        commonInit()
    }
    
    private func commonInit() {
        collectionView.setCollectionViewLayout(makeLayout(), animated: false)
    }
    
    // MARK: - Layout
    
    private func makeLayout() -> UICollectionViewCompositionalLayout {
        return UICollectionViewCompositionalLayout { [weak self] (section, layoutEnvironment) -> NSCollectionLayoutSection? in
            var configuration = UICollectionLayoutListConfiguration(appearance: .sidebar)
            let header = self?.diffableDataSource?.getSection(index: section)?.header
            configuration.headerMode = (header == nil) ? .none : .firstItemInSection
            let footer = self?.diffableDataSource?.getSection(index: section)?.footer
            configuration.footerMode = (footer == nil) ? .none : .supplementary
            return NSCollectionLayoutSection.list(using: configuration, layoutEnvironment: layoutEnvironment)
        }
    }
}
#endif