Core Data浅谈系列之五 ： 在UITableView中展示

在逻辑上（表关系）将Team和Player关联起来后，我们将其展现到UI视图上。

首先，为App添加导航栏：

@interface AppDelegate : UIResponder <UIApplicationDelegate >@property (strong, nonatomic) UIWindow *window;@property (strong, nonatomic) UINavigationController *navController;@property (strong, nonatomic) ViewController *viewController;@end@implementation AppDelegate- (void)dealloc{[_window release];[_navController release];[_viewController release];[super dealloc];}- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];// Override point for customization after application launch.self.viewController = [[[ViewController alloc] initWithNibName:@"ViewController" bundle:nil] autorelease];self.navController = [[[UINavigationController alloc] initWithRootViewController:self.viewController] autorelease];self.window.rootViewController = self.navController;[self.window makeKeyAndVisible];return YES;}

然后在ViewController上添加一个UITableView，布局好并实现如下相应的代理函数：

#pragma mark – #pragma mark – UITableView DataSource- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{return 1;}- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{return [self.teamArray count];}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{static NSString *cellIdentifier = @"TeamTableViewCellIdentifier";UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];if (nil == cell) {cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellIdentifier] autorelease];}Team *teamObject = [self.teamArray objectAtIndex:indexPath.row];UIImage *nbaImage = [UIImage imageNamed:@"nba@2x.jpg"];cell.imageView.image = nbaImage;cell.imageView.backgroundColor = [UIColorredColor];cell.textLabel.text = teamObject.name;cell.detailTextLabel.text = teamObject.city;cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;return cell;}#pragma mark – #pragma mark – UITableView Delegate- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{[tableView deselectRowAtIndexPath:indexPath animated:YES];Team *teamObject = [self.teamArray objectAtIndex:indexPath.row];PlayerListViewController *playerListVC = [[[PlayerListViewController alloc] init] autorelease];playerListVC.team = teamObject;playerListVC.cdViewController = self;[self.navigationController pushViewController:playerListVC animated:YES];}

在插入一些球队信息后，可以得到如下效果（按球队名称排序）：

– (NSArray *)fetchTeamList{NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];NSEntityDescription *teamEntity = [NSEntityDescription entityForName:@"Team" inManagedObjectContext:self.managedObjectContext];[fetchRequest setEntity:teamEntity];NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"name"ascending:YES];[fetchRequest setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]];NSError *error = NULL;NSArray *array = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];if (error) {NSLog(@"Error : %@\n", [error localizedDescription]);}[fetchRequest release], fetchRequest = nil;return array;}

点击cell，，就进入到该队的球员列表：

– (NSArray *)fetchPlayerList{NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];NSEntityDescription *teamEntity = [NSEntityDescription entityForName:@"Player" inManagedObjectContext:self.cdViewController.managedObjectContext];[fetchRequest setEntity:teamEntity];NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"age"ascending:YES];[fetchRequest setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]];NSPredicate *predicate = [NSPredicate predicateWithFormat:@"team == %@", self.team];[fetchRequest setPredicate:predicate];NSError *error = NULL;NSArray *array = [self.cdViewController.managedObjectContext executeFetchRequest:fetchRequest error:&error];if (error) {NSLog(@"Error : %@\n", [error localizedDescription]);}[fetchRequest release], fetchRequest = nil;return array;}

通过导航栏右边的Add按钮来添加球员信息：

– (IBAction)addBtnDidClick:(id)sender{// We don't check the user input.Player *playerObject = [NSEntityDescription insertNewObjectForEntityForName:@"Player" inManagedObjectContext:self.cdViewController.managedObjectContext];playerObject.name = self.nameTextField.text;playerObject.age = [NSNumber numberWithInteger:[self.ageTextField.text integerValue]];playerObject.team = self.team;[self.cdViewController saveContext];[self dismissModalViewControllerAnimated:YES];}- (IBAction)cancelBtnDidClick:(id)sender{[self dismissModalViewControllerAnimated:YES];}

以上对NSManagedObject的操作都位于同一份NSManagedObjectContext中。如上面添加球员的函数addBtnDidClick:所注释的，添加球员信息时并没有对数据进行验证 —— 这将在下一篇讨论。

Brief Talk About Core Data Series, Part 5 : Showing in UITableView

Jason Lee @ Hangzhou

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