ios coredata sqlite3 NSFetchedResultsController(2)

//
//  RootViewController.m
//  FetchedResultsController
//
//  Created by 何瑾 on 15/1/16.
//  Copyright (c) 2015年 e世雕龙. All rights reserved.
//

#import "RootViewController.h"
#import "Student.h"

@interface RootViewController ()

@property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;// 托管对象上下文
@property (strong, nonatomic) NSFetchedResultsController *fetchedResultsController;// 抓取结果控制器

@end

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // 1、获取应用程序对象(单例)
    UIApplication *app = [UIApplication sharedApplication];
    // 2、获取应用程序委托
    id appDelegate = app.delegate;
    // 3、获取托管对象上下文
    self.managedObjectContext = [appDelegate managedObjectContext];
    // 4、创建抓取请求对象
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Student"];
    // 4.1、创建排序规则
    NSSortDescriptor *sd1 = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];
    // 4.2、设置抓取请求对象的排序规则属性
    [request setSortDescriptors:@[sd1]];
    // 5、创建抓取结果控制器(1、给表视图提供数据。2、监控CoreData数据变化，回调四个委托方法)
    self.fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:request managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:@"stu"];
    // 5.1指定抓取结果控制器的委托，在CoreData中对象发生变化时调用相关委托方法
    self.fetchedResultsController.delegate = self;
    // 6、执行抓取
    __autoreleasing NSError *error = nil;
    [self.fetchedResultsController performFetch:&error];
    if (error) {
        [self myAlert:[error localizedDescription]];
    }
}

#pragma mark 通过CoreData添加对象
- (IBAction)addObject:(id)sender {
    //使用实体描述对象把一个空的数据模型（托管对象）放入托管对象上下文中
    Student *stu = [NSEntityDescription insertNewObjectForEntityForName:@"Student" inManagedObjectContext:self.managedObjectContext];
    //设置托管对象属性值
    static int i = 0;
    i++;
    stu.name = [NSString stringWithFormat:@"何瑾%d",i];
    stu.phoneNumber = @18888888888;
    //保存托管对象上下文
    __autoreleasing NSError *error = nil;
    [self.managedObjectContext save:&error];
    if (error) {
        NSLog(@"%@",[error localizedDescription]);
        [self myAlert:[error localizedDescription]];
    }
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return [[self.fetchedResultsController sections] count];
}

- (NSInteger)tableView:(UITableView *)table numberOfRowsInSection:(NSInteger)section {
    if ([[self.fetchedResultsController sections] count] > 0) {
        id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section];
        return [sectionInfo numberOfObjects];
    } else
        return 0;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    
    // 创建出列可重用标识符
    static NSString *cellID = @"cellID";
    // 从出列可重用队列中获取单元格
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellID];
    // 如果没有则创建
    if (!cell) {
        cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellID];
    }
    Student *stu = [self.fetchedResultsController objectAtIndexPath:indexPath];
    // Configure the cell with data from the managed object.
    cell.textLabel.text = stu.name;
    cell.detailTextLabel.text = [stu.phoneNumber stringValue];
    return cell;
}

/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
    // Return NO if you do not want the specified item to be editable.
    return YES;
}
*/

// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source
        // 只需要删除CoreData中对象
        // 从CoreData的托管对象上下文中获取模型对象
        Student *stu = [self.fetchedResultsController objectAtIndexPath:indexPath];
        // 从CoreData的托管对象上下文中删除对象
        [self.managedObjectContext deleteObject:stu];
        // 保存上下文
        __autoreleasing NSError *error = nil;
        [self.managedObjectContext save:&error];
        if (error) {
            [self myAlert:[error localizedDescription]];
        }
    } else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }   
}

/*
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {
}
*/

/*
// Override to support conditional rearranging of the table view.
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath {
    // Return NO if you do not want the item to be re-orderable.
    return YES;
}
*/

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/
#pragma Table view delegate
- (NSString *)tableView:(UITableView *)tableView titleForDeleteConfirmationButtonForRowAtIndexPath:(NSIndexPath *)indexPath {
    return @"删除";
}
#pragma mark 封装UIAlertView
- (void)myAlert:(NSString *)errorMsg {
    UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"信息" message:errorMsg delegate:self cancelButtonTitle:@"确定" otherButtonTitles:nil];
    [alert show];
}
#pragma mark NSFetchedResultsControllerDelegate methods
/*
 Assume self has a property 'tableView' -- as is the case for an instance of a UITableViewController
 subclass -- and a method configureCell:atIndexPath: which updates the contents of a given cell
 with information from a managed object at the given index path in the fetched results controller.
 */
// 告知tableView开始进行数据变化，此时tableView将会记录变化点，当所有变化结束之后，统一进行UI的刷新
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
    [self.tableView beginUpdates];
}

// 表视图分区变化回调此委托方法
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {
    
    switch(type) {
        case NSFetchedResultsChangeInsert:
            [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex]
                          withRowAnimation:UITableViewRowAnimationFade];
            break;
            
        case NSFetchedResultsChangeDelete:
            [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex]
                          withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

// 根据CoreData数据变化类型进行表视图更新（增、删、改、移动）
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath {
    
    UITableView *tableView = self.tableView;
    
    switch(type) {
        // 增加
        case NSFetchedResultsChangeInsert:
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
                             withRowAnimation:UITableViewRowAnimationFade];
            break;
        // 删除
        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
                             withRowAnimation:UITableViewRowAnimationFade];
            break;
        // 修改
        case NSFetchedResultsChangeUpdate:
            [tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;
        // 移动
        case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
                             withRowAnimation:UITableViewRowAnimationFade];
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
                             withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

// 通知tableView数据变化结束，开始进行UI刷新
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
    [self.tableView endUpdates];
}
@end