RxSwift源码分析(23)——DataSource

上一篇探索了一下tableView和RxSwift使用，如果遇到分组数据的情况，RxSwift依然有提供相关方法，比如下面例子：

let tableViewDataSource = RxTableViewSectionedReloadDataSource<SectionModel<String, SectionModel>>(configureCell: { (dataSource, tableView, indexPath, model) -> TestTableViewCell in
        let cell = tableView.dequeueReusableCell(withIdentifier: "TestTableViewCell", for: indexPath) as! TestTableViewCell
        cell.setSectionData(model)
        return cell
}, titleForHeaderInSection: { (dataSource, index) -> String in
        return dataSource.sectionModels[index].title
})
//绑定
dataDriver.drive(tableView.rx.items(dataSource: tableViewDataSource))
.disposed(by: disposeBag)

• 源码分析

RxTableViewSectionedReloadDataSource继承了TableViewSectionedDataSource，TableViewSectionedDataSource拥有很多默认初始化的闭包，这些闭包都会在DataSource协议里调用，从而实现在外面自定义Section：

open class RxTableViewSectionedReloadDataSource<Section: SectionModelType>
    : TableViewSectionedDataSource<Section>
    , RxTableViewDataSourceType {
    ...
}

open class TableViewSectionedDataSource<Section: SectionModelType>
    : NSObject
    , UITableViewDataSource
    , SectionedViewDataSourceType {
    
    public typealias Item = Section.Item

    public typealias ConfigureCell = (TableViewSectionedDataSource<Section>, UITableView, IndexPath, Item) -> UITableViewCell
    public typealias TitleForHeaderInSection = (TableViewSectionedDataSource<Section>, Int) -> String?
    public typealias TitleForFooterInSection = (TableViewSectionedDataSource<Section>, Int) -> String?
    public typealias CanEditRowAtIndexPath = (TableViewSectionedDataSource<Section>, IndexPath) -> Bool
    public typealias CanMoveRowAtIndexPath = (TableViewSectionedDataSource<Section>, IndexPath) -> Bool

    #if os(iOS)
        public typealias SectionIndexTitles = (TableViewSectionedDataSource<Section>) -> [String]?
        public typealias SectionForSectionIndexTitle = (TableViewSectionedDataSource<Section>, _ title: String, _ index: Int) -> Int
    #endif

    #if os(iOS)
        public init(
                configureCell: @escaping ConfigureCell,
                titleForHeaderInSection: @escaping  TitleForHeaderInSection = { _, _ in nil },
                titleForFooterInSection: @escaping TitleForFooterInSection = { _, _ in nil },
                canEditRowAtIndexPath: @escaping CanEditRowAtIndexPath = { _, _ in false },
                canMoveRowAtIndexPath: @escaping CanMoveRowAtIndexPath = { _, _ in false },
                sectionIndexTitles: @escaping SectionIndexTitles = { _ in nil },
                sectionForSectionIndexTitle: @escaping SectionForSectionIndexTitle = { _, _, index in index }
            ) {
            self.configureCell = configureCell
            self.titleForHeaderInSection = titleForHeaderInSection
            self.titleForFooterInSection = titleForFooterInSection
            self.canEditRowAtIndexPath = canEditRowAtIndexPath
            self.canMoveRowAtIndexPath = canMoveRowAtIndexPath
            self.sectionIndexTitles = sectionIndexTitles
            self.sectionForSectionIndexTitle = sectionForSectionIndexTitle
        }
    #else
    ...
    #endif
    ...
    // UITableViewDataSource
    
    open func numberOfSections(in tableView: UITableView) -> Int {
        return _sectionModels.count
    }
    
    open func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        guard _sectionModels.count > section else { return 0 }
        return _sectionModels[section].items.count
    }
    
    open func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        precondition(indexPath.item < _sectionModels[indexPath.section].items.count)
        
        return configureCell(self, tableView, indexPath, self[indexPath])
    }
    
    open func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        return titleForHeaderInSection(self, section)
    }
   
    open func tableView(_ tableView: UITableView, titleForFooterInSection section: Int) -> String? {
        return titleForFooterInSection(self, section)
    }
    
    open func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
        return canEditRowAtIndexPath(self, indexPath)
    }
   
    open func tableView(_ tableView: UITableView, canMoveRowAt indexPath: IndexPath) -> Bool {
        return canMoveRowAtIndexPath(self, indexPath)
    }

    open func tableView(_ tableView: UITableView, moveRowAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {
        self._sectionModels.moveFromSourceIndexPath(sourceIndexPath, destinationIndexPath: destinationIndexPath)
    }

    #if os(iOS)
    open func sectionIndexTitles(for tableView: UITableView) -> [String]? {
        return sectionIndexTitles(self)
    }
    
    open func tableView(_ tableView: UITableView, sectionForSectionIndexTitle title: String, at index: Int) -> Int {
        return sectionForSectionIndexTitle(self, title, index)
    }
    #endif
}