Swift教程_CoreData实例（三）_构建控制层（列表数据加载、删除数据）

Swift教程_CoreData实例（一）_构建storyboard

Swift教程_CoreData实例（二）_构建数据层

Swift教程_CoreData实例（三）_构建控制层（列表数据加载、删除数据）

Swift教程_CoreData实例（四）_构建控制层（查询、更新数据）

Swift教程_CoreData实例（五）_构建控制层（添加数据）

四、构建控制层

控制层总体结构包括列表的数据加载、数据的新增、删除、更新。这里我们先来搞定列表controller的功能（数据加载、删除），即PKOBooksTableViewController。

1.列表数据加载、删除数据

我们自定义一个列表控制器PKOBooksTableViewController，并应用到storyboard的列表中。通过NSFetchedResultsController对象来查询、删除数据。

代码如下，注释非常详尽：

import UIKitimport CoreDataclass PKOBooksTableViewController: UITableViewController,NSFetchedResultsControllerDelegate {        var managedObjectContext: NSManagedObjectContext?    //获取数据的控制器    var fetchedResultsController: NSFetchedResultsController?        override func viewDidLoad() {        super.viewDidLoad()                //为导航栏左边按钮设置编辑按钮        self.navigationItem.leftBarButtonItem = self.editButtonItem()                //执行获取数据，并处理异常        var error: NSError? = nil        if !self.initFetchedResultsController().performFetch(&error){            NSLog("Unresolved error \(error), \(error!.userInfo)")            abort()        }    }        override func didReceiveMemoryWarning() {        super.didReceiveMemoryWarning()    }        //设置单元格的信息    func setCellInfo(cell: UITableViewCell, indexPath: NSIndexPath) {        var book = self.fetchedResultsController?.objectAtIndexPath(indexPath) as Book        NSLog("======\(book.title)")        cell.textLabel.text = book.title    }        // MARK: - Table view data source        override func numberOfSectionsInTableView(tableView: UITableView) -> Int {        //分组数量        return self.fetchedResultsController!.sections!.count    }        override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {        //每个分组的数据数量        var section = self.fetchedResultsController!.sections![section] as NSFetchedResultsSectionInfo        return section.numberOfObjects    }            override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {        let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as UITableViewCell        // 为列表Cell赋值        self.setCellInfo(cell, indexPath: indexPath)        return cell    }        override func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {        //分组表头显示        return self.fetchedResultsController!.sections![section].name    }        /*    // Override to support conditional editing of the table view.    override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {    // Return NO if you do not want the specified item to be editable.    return true    }    */        // 自定义编辑单元格时的动作，可编辑样式包括UITableViewCellEditingStyleInsert（插入）、UITableViewCellEditingStyleDelete（删除）。    override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {        if editingStyle == .Delete {            //删除sqlite库中对应的数据            var context = self.fetchedResultsController?.managedObjectContext            context!.deleteObject(self.fetchedResultsController?.objectAtIndexPath(indexPath) as NSManagedObject)            //删除后要进行保存            var error: NSError? = nil            if context?.save(&error) == nil {                NSLog("Unresolved error \(error), \(error!.userInfo)")                abort()            }        } else if editingStyle == .Insert {        }    }        /*    // Override to support rearranging the table view.    override func tableView(tableView: UITableView, moveRowAtIndexPath fromIndexPath: NSIndexPath, toIndexPath: NSIndexPath) {        }    */        // Override to support conditional rearranging of the table view.    override func tableView(tableView: UITableView, canMoveRowAtIndexPath indexPath: NSIndexPath) -> Bool {        // 移动单元格时不要重新排序        return false    }        // MARK: - NSFetchedResultsController delegate methods to respond to additions, removals and so on.        //初始化获取数据的控制器    func initFetchedResultsController() ->NSFetchedResultsController    {        if self.fetchedResultsController != nil {            return self.fetchedResultsController!        }        // 创建一个获取数据的实例，用来查询实体        var fetchRequest = NSFetchRequest()        var entity = NSEntityDescription.entityForName("Book", inManagedObjectContext: self.managedObjectContext!)        fetchRequest.entity = entity                // 创建排序规则        var authorDescriptor = NSSortDescriptor(key: "author", ascending: true)        var titleDescriptor = NSSortDescriptor(key: "title", ascending: true)        var sortDescriptors = [authorDescriptor, titleDescriptor]        fetchRequest.sortDescriptors = sortDescriptors                // 创建获取数据的控制器，将section的name设置为author，可以直接用于tableViewSourceData        var fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext!, sectionNameKeyPath: "author", cacheName: "Root")        fetchedResultsController.delegate = self        self.fetchedResultsController = fetchedResultsController        return fetchedResultsController    }        //通知控制器即将开始处理一个或多个的单元格变化，包括添加、删除、移动或更新。在这里处理变化时对tableView的影响，例如删除sqlite数据时同时要删除tableView中对应的单元格    func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {        switch(type) {        case .Insert:            self.tableView.insertRowsAtIndexPaths([newIndexPath!], withRowAnimation: UITableViewRowAnimation.Automatic)        case .Delete:            self.tableView.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: UITableViewRowAnimation.Automatic)        case .Update:            self.setCellInfo(self.tableView.cellForRowAtIndexPath(indexPath!)!, indexPath: indexPath!)        case .Move:            self.tableView.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: UITableViewRowAnimation.Automatic)            self.tableView.insertRowsAtIndexPaths([indexPath!], withRowAnimation: UITableViewRowAnimation.Automatic)        }    }        //通知控制器即将开始处理一个或多个的分组变化，包括添加、删除、移动或更新。    func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {        switch(type) {        case .Insert:            self.tableView.insertSections(NSIndexSet(index: sectionIndex), withRowAnimation: UITableViewRowAnimation.Automatic)        case .Delete:            self.tableView.deleteSections(NSIndexSet(index: sectionIndex), withRowAnimation: UITableViewRowAnimation.Automatic)        case .Update:            break        case .Move:            break        }    }    //通知控制器即将有变化    func controllerWillChangeContent(controller: NSFetchedResultsController) {        //tableView启动变更，需要endUpdates来结束变更，类似于一个事务，统一做变化处理        self.tableView.beginUpdates()    }        //通知控制器变化完成    func controllerDidChangeContent(controller: NSFetchedResultsController) {        self.tableView.endUpdates()    }    /*    // MARK: - Navigation        // In a storyboard-based application, you will often want to do a little preparation before navigation    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {    // Get the new view controller using [segue destinationViewController].    // Pass the selected object to the new view controller.    }    */    }

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