littleWhale

iOS工程师都知道tableview 在开发中是用得最多的，大部分页面几乎都可以用列表来做。但有没发现大量工作其实是重复的比如cell的注册，delegate数据源的匹配，cell的类型转换。接下来，我们需要将这些代理方法为tableview提供数据封装成数据模型。
数据源：dataSource[section[ rows],section[ rows]]

封装DataSource

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struct Section<Item> {
    var items: [Item]
}

struct DataSource<Item> {
    var sections: [Section<Item>]

    func numberOfSections() -> Int {
        return sections.count
    }

    func numberOfItems(in section: Int) -> Int {
        guard section < sections.count else { return 0 }
        return sections[section].items.count
    }

    func item(at indexPath: IndexPath) -> Item {
        return sections[indexPath.section].items[indexPath.row]
    }
}

Table Config

列表配置基本包含三项：重用标识，注册cell，配置cell

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//table config
protocol ConfiguratorType {
    associatedtype Item
    associatedtype Cell: UITableViewCell

    func reuseIdentifier(for item: Item, indexPath: IndexPath) -> String
    func configuredCell(for item: Item, tableView: UITableView, indexPath: IndexPath) -> Cell
    func registerCells(in tableView: UITableView)
}

//构建配置器。泛型Item, Cell
struct Configurator<Item, Cell: UITableViewCell>: ConfiguratorType {
    typealias CellConfigurator = (Cell, Item, UITableView, IndexPath) -> Cell

    let configurator: CellConfigurator
    let reuseIdentifier = "\(Cell.self)"

    func reuseIdentifier(for item: Item, indexPath: IndexPath) -> String {
        return reuseIdentifier
    }

    func configure(cell: Cell, item: Item, tableView: UITableView, indexPath: IndexPath) -> Cell {
        return configurator(cell, item, tableView, indexPath)
    }

    func registerCells(in tableView: UITableView) {
        if let path = Bundle.main.path(forResource: "\(Cell.self)", ofType: "nib"),
            FileManager.default.fileExists(atPath: path) {
            let nib = UINib(nibName: "\(Cell.self)", bundle: .main)
            tableView.register(nib, forCellReuseIdentifier: reuseIdentifier)
        } else {
            tableView.register(Cell.self, forCellReuseIdentifier: reuseIdentifier)
        }
    }

    func configuredCell(for item: Item, tableView: UITableView, indexPath: IndexPath) -> Cell {
        let reuseIdentifier = self.reuseIdentifier(for: item, indexPath: indexPath)
        let cell = tableView.dequeueReusableCell(withIdentifier: reuseIdentifier, for: indexPath) as! Cell
        return self.configure(cell: cell, item: item, tableView: tableView, indexPath: indexPath)
    }
}

多类型cell配置器

假如我们的一个业务列表由两种cell组成:TableCell,NibCell。那么我们提供重用标识，配置cell时候就需要做好枚举判断。

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enum CellType {
    typealias Model = String
    typealias AnotherModel = String

    case cell(Model)
    case anotherCell(AnotherModel)
}

class TableCell: UITableViewCell {

}
class NibCell: UITableViewCell {

}

struct MoreCellsConfigurator: ConfiguratorType {
    let cellConfigurator: Configurator<CellType.Model, TableCell>
    let anotherCellConfigurator: Configurator<CellType.AnotherModel, NibCell>

    func reuseIdentifier(for item: CellType, indexPath: IndexPath) -> String {
        switch item {
        case .cell:
            return cellConfigurator.reuseIdentifier
        case .anotherCell:
            return anotherCellConfigurator.reuseIdentifier
        }
    }

    func configuredCell(for item: CellType, tableView: UITableView, indexPath: IndexPath) -> UITableViewCell {
        switch item {
        case .cell(let model):
            return cellConfigurator.configuredCell(for: model, tableView: tableView, indexPath: indexPath)
        case .anotherCell(let model):
            return anotherCellConfigurator.configuredCell(for: model, tableView: tableView, indexPath: indexPath)
        }
    }

    func registerCells(in tableView: UITableView) {
        cellConfigurator.registerCells(in: tableView)
        anotherCellConfigurator.registerCells(in: tableView)
    }
}

使用多cells配置器

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class ExampleTableViewController<Item, Cell: UITableViewCell>: UITableViewController{

    let dataSource: DataSource<Item>
    let configurator: MoreCellsConfigurator

    init(dataSource: DataSource<Item>, configurator: MoreCellsConfigurator) {
        self.dataSource = dataSource
        self.configurator = configurator
        super.init(nibName: nil, bundle: nil)
        configurator.registerCells(in: tableView)
    }

    @available(*, unavailable)
    required init?(coder aDecoder: NSCoder) { fatalError() }

    override func numberOfSections(in tableView: UITableView) -> Int {
        return dataSource.numberOfSections()
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return dataSource.numberOfItems(in: section)
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let item = dataSource.item(at: indexPath) as! CellType

        return configurator.configuredCell(for: item, tableView: tableView, indexPath: indexPath)
    }
}

demo控制器举例

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extension UIViewController {
    func add(child: UIViewController, container: UIView, configure: (_ childView: UIView) -> Void = { _ in }) {
        addChild(child)
        container.addSubview(child.view)
        configure(child.view)
        child.didMove(toParent: self)
    }
}

class GYViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        setupTable()
    }

    func setupTable() {
        let section0 = Section<CellType>(items: [.cell("a"), .anotherCell("2"), .cell("c")])
        let section1 = Section<CellType>(items: [.anotherCell("1"), .cell("b"), .anotherCell("3")])
        let dataSource = DataSource(sections: [section0, section1])

        //TableCell配置器
        let configurator1 = Configurator { (cell, model: CellType.Model, tableView, indexPath) -> TableCell in
            cell.textLabel?.text = model
            return cell
        }

        //NibCell配置器
        let configurator2 = Configurator { (cell, model: CellType.AnotherModel, tableView, indexPath) -> NibCell in
            cell.textLabel?.text = model
            return cell
        }

        //配置多种cell配置器
        let aggregate = MoreCellsConfigurator(cellConfigurator: configurator1, anotherCellConfigurator: configurator2)

        let table = ExampleTableViewController(dataSource: dataSource, configurator: aggregate)

        add(child: table, container: view) { childView in
            //布局约束
            childView.frame = view.frame
        }
    }
}

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