核心数据详细信息视图与关系

本文介绍了核心数据详细信息视图与关系的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 29岁程序员，3月因学历无情被辞！ 我已在我的核心数据实体上设置了一对多关系。我试图显示相关数据的detailview副本。目前我有prepareforseague：方法使用原始实体（Routines），但我失去了如何显示链接实体（RoutinesDetails）。 FBCDRoutineViewController - （void）viewDidAppear：（BOOL）animated { [super viewDidAppear：animated ]; //从持久性数据存储中获取设备 NSManagedObjectContext * managedObjectContext = [self managedObjectContext]; NSFetchRequest * fetchRequest = [[NSFetchRequest alloc] initWithEntityName：@Routines]; self.routines = [[managedObjectContext executeFetchRequest：fetchRequest error：nil] mutableCopy]; [self.tableView reloadData]; } - （void）prepareForSegue：（UIStoryboardSegue *）segue sender：（id）sender { if [[segue identifier] isEqualToString：@ UpdateDevice]）{ NSManagedObject * selectedDevice = [self.routines objectAtIndex：[[self.tableView indexPathForSelectedRow] row]]; FBCDRoutineViewController * destViewController = segue.destinationViewController; destViewController.routines = selectedDevice; } FBCDRoutineDetailViewController - （NSManagedObjectContext *）managedObjectContext { NSManagedObjectContext * context = nil; id delegate = [[UIApplication sharedApplication] delegate]; if（[delegate performSelector：@selector（managedObjectContext）]）{ context = [delegate managedObjectContext]; } return context; } - （id）initWithStyle：（UITableViewStyle）style { self = [super initWithStyle：style]; if（self）{ //自定义初始化} return self; } - （void）viewDidAppear：（BOOL）animated { [super viewDidAppear：animated]; //从持久性数据存储中获取设备 NSManagedObjectContext * managedObjectContext = [self managedObjectContext]; NSFetchRequest * fetchRequest = [[NSFetchRequest alloc] initWithEntityName：@RoutinesDetails]; self.routines = [[managedObjectContext executeFetchRequest：fetchRequest error：nil] mutableCopy]; } - （void）viewDidLoad { [[self navigationController] setNavigationBarHidden：NO animated：YES]; [super viewDidLoad]; //在加载视图之后执行任何其他设置。 if（self.routines）{ [self.testLabel setText：[self.routines valueForKey：@routinename]]; } } FBCDRoutineDetailViewController @property（strong）NSManagedObject * routines; 这是我第一次使用核心数据，我正在查看如何显示Details实体。我接近得到它的工作？如果不是，我可以得到指向我应该看什么。 有任何建议吗？解决方案您要显示与 prepareForSegue 中传递的 Routines 对象相关的所有对象。 然后在 FBCDRoutineDetailViewController 中声明两个属性： @property（strong）NSManagedObject * routines; //传递的对象 @property（strong）NSManagedObject * routineDetails; //显示的细节对象 并按如下方式获取： NSManagedObjectContext * managedObjectContext = [self managedObjectContext]; NSFetchRequest * fetchRequest = [[NSFetchRequest alloc] initWithEntityName：@RoutinesDetails]; NSPredicate * predicate = [NSPredicate predicateWithFormat：@routineinfo ==％@，self.routines]; [fetchRequest setPredicate：predicate]; NSError * error; self.routineDetails = [managedObjectContext executeFetchRequest：fetchRequest error：& error]; self.routineDetails 现在是数据源 （注意：为了在表视图中显示Core Data请求的结果集，，您可能还会考虑使用 NSFetchedResultsController 。） I have set up a 1 to many relationship on my core data entities. I am trying to show the detailview copy of the associated data. Currently I have the prepareforseague: method working with the original entity(Routines), however I am at a lose as to how to show the linked entity (RoutinesDetails).FBCDRoutineViewController - (void)viewDidAppear:(BOOL)animated{ [super viewDidAppear:animated]; // Fetch the devices from persistent data store NSManagedObjectContext *managedObjectContext = [self managedObjectContext]; NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Routines"]; self.routines = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy]; [self.tableView reloadData];} - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { if ([[segue identifier] isEqualToString:@"UpdateDevice"]) { NSManagedObject *selectedDevice = [self.routines objectAtIndex:[[self.tableView indexPathForSelectedRow] row]]; FBCDRoutineViewController *destViewController = segue.destinationViewController; destViewController.routines = selectedDevice; }FBCDRoutineDetailViewController- (NSManagedObjectContext *)managedObjectContext { NSManagedObjectContext *context = nil; id delegate = [[UIApplication sharedApplication] delegate]; if ([delegate performSelector:@selector(managedObjectContext)]) { context = [delegate managedObjectContext]; } return context;}- (id)initWithStyle:(UITableViewStyle)style{ self = [super initWithStyle:style]; if (self) { // Custom initialization } return self;}- (void)viewDidAppear:(BOOL)animated{ [super viewDidAppear:animated]; // Fetch the devices from persistent data store NSManagedObjectContext *managedObjectContext = [self managedObjectContext]; NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"RoutinesDetails"]; self.routines = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];}- (void)viewDidLoad{ [[self navigationController] setNavigationBarHidden:NO animated:YES]; [super viewDidLoad]; // Do any additional setup after loading the view. if (self.routines) { [self.testLabel setText:[self.routines valueForKey:@"routinename"]]; }}FBCDRoutineDetailViewController@property (strong) NSManagedObject *routines;This is my first time with core data and I am looking at how to show the Details entity. Am I Close to getting it working? If not can I get directed at to what I should be looking at.Any suggestions? 解决方案 If I understand your problem correctly, you want to display all RoutinesDetails objectsthat are related to the Routines object passed in prepareForSegue.Then you would declare two properties in the FBCDRoutineDetailViewController:@property (strong) NSManagedObject *routines; // the passed object@property (strong) NSManagedObject *routineDetails; // the displayed details objectsand fetch them like this:NSManagedObjectContext *managedObjectContext = [self managedObjectContext];NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"RoutinesDetails"];NSPredicate *predicate = [NSPredicate predicateWithFormat:@"routineinfo == %@", self.routines];[fetchRequest setPredicate:predicate];NSError *error;self.routineDetails = [managedObjectContext executeFetchRequest:fetchRequest error:&error];self.routineDetails is now the data source array for the details view.(Remark: For displaying the result set of a Core Data request in a table view,you might also consider to use a NSFetchedResultsController.) 这篇关于核心数据详细信息视图与关系的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！