iOS，Coredata：子类别的总和值在viewdidload上未准备就绪，并且此后未更新_Ios_Core Data

iOS，Coredata：子类别的总和值在viewdidload上未准备就绪，并且此后未更新

ios core-data

iOS，Coredata：子类别的总和值在viewdidload上未准备就绪，并且此后未更新,ios,core-data,Ios,Core Data,我有一个基本的数据模型。主类别有几个子类别。在每个子类别中，您定义了每年预算的金额。所以我想： a）每个主要类别的所有子类别支出的总和。 b）作为总预算的所有主要类别支出的总和然而，目前这还不起作用。我在viewWillExample方法中设置了textfield（因为我一直希望在再次打开视图时更新它）。第一次加载时，总和为0。切换到另一个视图并返回后，将显示正确的总和。之后，它不会自我更新。为什么呢我是Coredata的新手。与我在这里执行的查询相比，获取属性可能是更好的方法吗？以下是

我有一个基本的数据模型。主类别有几个子类别。在每个子类别中，您定义了每年预算的金额。所以我想：

a）每个主要类别的所有子类别支出的总和。 b）作为总预算的所有主要类别支出的总和

然而，目前这还不起作用。我在viewWillExample方法中设置了textfield（因为我一直希望在再次打开视图时更新它）。第一次加载时，总和为0。切换到另一个视图并返回后，将显示正确的总和。之后，它不会自我更新。为什么呢

我是Coredata的新手。与我在这里执行的查询相比，获取属性可能是更好的方法吗？以下是相关的代码部分：

我的主视图控制器（此处显示所有主要类别的总预算）：

数据库获取：

+ (NSNumber *)budgetPerMonthForManagedObjectContext:(NSManagedObjectContext *)context
{
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"MainCategory"];
    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"position" ascending:NO];
    request.sortDescriptors = [NSArray arrayWithObject:sortDescriptor];

    NSArray *matches = [context executeFetchRequest:request error:nil];
    CostsPeriodically *totalCostPerMonth = [[CostsPeriodically alloc]init];

    for (MainCategory *mainCategory in matches) {
        for (SpendingCategory *category in mainCategory.hasSpendingCategories){
            [totalCostPerMonth addCosts:category.costPerYear];
        }
    }

    return totalCostPerMonth.sumPerMonth;
}

编辑：以下是整个获取结果控制器设置方法：

- (void)setupFetchedResultsController
{
    NSError *error = nil;
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"MainCategory"];
    request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"position" ascending:YES]];
    [self.budgetDatabase.managedObjectContext executeFetchRequest:request error:&error];

    self.fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:request
                                                                       managedObjectContext:self.budgetDatabase.managedObjectContext
                                                                         sectionNameKeyPath:nil
                                                                                  cacheName:nil];
}

-(void)useDocument
{
    if(![[NSFileManager defaultManager]fileExistsAtPath:[self.budgetDatabase.fileURL path]]){
        [self.budgetDatabase saveToURL:self.budgetDatabase.fileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
            [self setupFetchedResultsController];
            //[self initializeDatabaseWithData];
        }];
    } else if (self.budgetDatabase.documentState == UIDocumentStateClosed){
        [self.budgetDatabase openWithCompletionHandler:^(BOOL success){
            [self setupFetchedResultsController];
        }];
    } else if (self.budgetDatabase.documentState == UIDocumentStateNormal){
        [self setupFetchedResultsController];
    }
}

-(void)setBudgetDatabase:(UIManagedDocument *)budgetDatabase
{
    if(_budgetDatabase != budgetDatabase){
        _budgetDatabase = budgetDatabase;
        [self useDocument];
    }
}

进一步编辑，整个获取结果控制器类：

@synthesize fetchedResultsController = _fetchedResultsController;
@synthesize suspendAutomaticTrackingOfChangesInManagedObjectContext = _suspendAutomaticTrackingOfChangesInManagedObjectContext;
@synthesize debug = _debug;
@synthesize beganUpdates = _beganUpdates;
@synthesize reordering = _reordering;
@synthesize tableView = _tableView;

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}

#pragma mark - Fetching

- (void)performFetch
{
    if (self.fetchedResultsController) {
        if (self.fetchedResultsController.fetchRequest.predicate) {
            if (self.debug) NSLog(@"[%@ %@] fetching %@ with predicate: %@", NSStringFromClass([self class]), NSStringFromSelector(_cmd), self.fetchedResultsController.fetchRequest.entityName, self.fetchedResultsController.fetchRequest.predicate);
        } else {
            if (self.debug) NSLog(@"[%@ %@] fetching all %@ (i.e., no predicate)", NSStringFromClass([self class]), NSStringFromSelector(_cmd), self.fetchedResultsController.fetchRequest.entityName);
        }
        NSError *error;
        [self.fetchedResultsController performFetch:&error];
        if (error) NSLog(@"[%@ %@] %@ (%@)", NSStringFromClass([self class]), NSStringFromSelector(_cmd), [error localizedDescription], [error localizedFailureReason]);
    } else {
        if (self.debug) NSLog(@"[%@ %@] no NSFetchedResultsController (yet?)", NSStringFromClass([self class]), NSStringFromSelector(_cmd));
    }
    [self.tableView reloadData];
}

- (void)setFetchedResultsController:(NSFetchedResultsController *)newfrc
{
    NSFetchedResultsController *oldfrc = _fetchedResultsController;
    if (newfrc != oldfrc) {
        _fetchedResultsController = newfrc;
        newfrc.delegate = self;
        if ((!self.title || [self.title isEqualToString:oldfrc.fetchRequest.entity.name]) && (!self.navigationController || !self.navigationItem.title)) {
            self.title = newfrc.fetchRequest.entity.name;
        }
        if (newfrc) {
            if (self.debug) NSLog(@"[%@ %@] %@", NSStringFromClass([self class]), NSStringFromSelector(_cmd), oldfrc ? @"updated" : @"set");
            [self performFetch];
        } else {
            if (self.debug) NSLog(@"[%@ %@] reset to nil", NSStringFromClass([self class]), NSStringFromSelector(_cmd));
            [self.tableView reloadData];
        }
    }
}

#pragma mark - UITableViewDataSource

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [[[self.fetchedResultsController sections] objectAtIndex:section] numberOfObjects];
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    return [[[self.fetchedResultsController sections] objectAtIndex:section] name];
}

- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index
{
    return [self.fetchedResultsController sectionForSectionIndexTitle:title atIndex:index];
}

- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
    return [self.fetchedResultsController sectionIndexTitles];
}

#pragma mark - NSFetchedResultsControllerDelegate

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
    if(!self.reordering){
        if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext) {
            [self.tableView beginUpdates];
            self.beganUpdates = YES;
        }
    }
}

- (void)controller:(NSFetchedResultsController *)controller
  didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex
     forChangeType:(NSFetchedResultsChangeType)type
{
    if(!self.reordering){
        if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
        {
            switch(type)
            {
                case NSFetchedResultsChangeInsert:
                    [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                    break;

                case NSFetchedResultsChangeDelete:
                    [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                    break;
            }
        }
    }
}


- (void)controller:(NSFetchedResultsController *)controller
   didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath
     forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath
{
    if(!self.reordering){
        if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
        {
            switch(type)
            {
                case NSFetchedResultsChangeInsert:
                    [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
                    break;

                case NSFetchedResultsChangeDelete:
                    [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                    break;

                case NSFetchedResultsChangeUpdate:
                    [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                    break;

                case NSFetchedResultsChangeMove:
                    [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                    [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
                    break;
            }
        }
    }
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
    if(!self.reordering){
        if (self.beganUpdates) [self.tableView endUpdates];
    }
}

- (void)endSuspensionOfUpdatesDueToContextChanges
{
    _suspendAutomaticTrackingOfChangesInManagedObjectContext = NO;
}

- (void)setSuspendAutomaticTrackingOfChangesInManagedObjectContext:(BOOL)suspend
{
    if (suspend) {
        _suspendAutomaticTrackingOfChangesInManagedObjectContext = YES;
    } else {
        [self performSelector:@selector(endSuspensionOfUpdatesDueToContextChanges) withObject:0 afterDelay:0];
    }
}

@synthetic fetchedresultscoontroller=\u fetchedresultscoontroller；
@综合SuspendAutomaticTrackingOfchangesManagedObjectContext=\u SuspendAutomaticTrackingOfchangesManagedObjectContext；
@综合调试=_调试；
@合成起始更新=_起始更新；
@综合再排序=_再排序；
@综合tableView=\u tableView；
-（布尔）应自动旋转指针面定向：（UIInterfaceOrientation）interfaceOrientation
{
返回YES；
}
#pragma标记获取
-（空）穿孔
{
if（self.fetchedResultsController）{
if（self.fetchedResultsController.fetchRequest.predicate）{
if（self.debug）NSLog（@“[%@%@]获取%@带谓词：%@”、NSStringFromClass（[self class]）、NSStringFromSelector（_cmd）、self.fetchedResultsController.fetchRequest.entityName、self.fetchedResultsController.fetchRequest.predicate）；
}否则{
if（self.debug）NSLog（@“[%@%@]获取所有%@（即，无谓词）”、NSStringFromClass（[self class]）、NSStringFromSelector（_cmd）、self.fetchedResultsController.fetchRequest.entityName）；
}
n错误*错误；
[self.fetchedResultsController性能蚀刻：&错误]；
如果（错误）NSLog（@“[%@%@]%@（%@）”、NSStringFromClass（[self class]）、NSStringFromSelector（_cmd）、[error localizedDescription]、[error localizedFailureReason]）；
}否则{
如果（self.debug）NSLog（@“[%@%@]没有NSFetchedResultsController（尚未？）、NSStringFromClass（[self class]）、NSStringFromSelector（_cmd））；
}
[self.tableView重载数据]；
}
-（void）setFetchedResultsController:（NSFetchedResultsController*）新FRC
{
NSFetchedResultsController*oldfrc=\u fetchedResultsController；
如果（新FRC！=旧FRC）{
_fetchedResultsController=newfrc；
newfrc.delegate=self；
if（（！self.title | |[self.title IseQualtString:oldfrc.fetchRequest.entity.name]）&&（！self.navigationController | |！self.navigationItem.title））{
self.title=newfrc.fetchRequest.entity.name；
}
国际单项体育联合会（新财务报告准则）{
如果（self.debug）NSLog（@“[%@%@]@”、NSStringFromClass（[self class]）、NSStringFromSelector（_cmd）、oldfrc？@“更新”：“设置”）；
[自执行蚀刻]；
}否则{
如果（self.debug）NSLog（@“[%@%@]重置为nil”、NSStringFromClass（[self class]）、NSStringFromSelector（_cmd））；
[self.tableView重载数据]；
}
}
}
#pragma标记-UITableViewDataSource
-（NSInteger）表格视图中的节数：（UITableView*）表格视图
{
返回[[self.fetchedResultsController节]计数]；
}
-（NSInteger）表视图：（UITableView*）表视图行数节：（NSInteger）节
{
返回[[[self.fetchedResultsController节]对象索引：节]numberOfObjects]；
}
-（NSString*）表格视图：（UITableView*）表格视图标题标题标题部分：（NSInteger）部分
{
返回[[[self.fetchedResultsController节]对象索引：节]名称]；
}
-（NSInteger）tableView:（UITableView*）分区索引的tableView部分exttitle:（NSString*）标题索引：（NSInteger）索引
{
return[self.fetchedResultsController sectionForSectionIndexTitle:title-atIndex:index]；
}
-（NSArray*）sectionIndexTitlesForTableView:（UITableView*）表格视图
{
返回[self.fetchedResultsController节索引]；
}
#pragma标记-NSFetchedResultsControllerDelegate
-（void）controllerWillChangeContent:（NSFetchedResultsController*）控制器
{
如果（！自我重新排序）{
如果（！self.suspendAutomaticTrackingOffChangesManagedObjectContext）{
[self.tableView开始更新]；
self.beganUpdate=是；
}
}
}
-（void）控制器：（NSFetchedResultsController*）控制器
didChangeSection:（id）sectionInfo
atIndex:（整数）sectionIndex
forChangeType:（NSFetchedResultsChangeType）类型
{
如果（！自我重新排序）{
如果（！self.suspendAutomaticTrackingOffChangesManagedObjectContext）
{
开关（类型）
{
案例NSFetchedResultsChangesInsert：
[self.tableView insertSections:[NSIndexSet IndexSetWithiIndex:sectionIndex]带RowAnimation:UITableViewRowAnimationFade]；
打破
案例NSFetchedResultsChangeDelete：
[self.tableView deleteSections:[NSIndexSet IndexSetWithiIndex:sectionIndex]带RowAnimation:UITableViewRowAnimationFade]；
打破
}
}
}
}
-（void）控制器：（NSFetchedResultsController*）控制器
didChangeObject:（id）一个对象
atIndexPath:（nsindepath*）indepath
forChangeType:（NSFetchedResultsChangeType）类型
newindepath:（nsindepath*）newindepath
{
如果（！自我重新排序）{
如果（！self.suspendAutomaticTrackingOffChangesManagedObjectContext）
{
开关（类型）
{
案例NSFetchedResultsCh
@synthesize fetchedResultsController = _fetchedResultsController;
@synthesize suspendAutomaticTrackingOfChangesInManagedObjectContext = _suspendAutomaticTrackingOfChangesInManagedObjectContext;
@synthesize debug = _debug;
@synthesize beganUpdates = _beganUpdates;
@synthesize reordering = _reordering;
@synthesize tableView = _tableView;

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}

#pragma mark - Fetching

- (void)performFetch
{
    if (self.fetchedResultsController) {
        if (self.fetchedResultsController.fetchRequest.predicate) {
            if (self.debug) NSLog(@"[%@ %@] fetching %@ with predicate: %@", NSStringFromClass([self class]), NSStringFromSelector(_cmd), self.fetchedResultsController.fetchRequest.entityName, self.fetchedResultsController.fetchRequest.predicate);
        } else {
            if (self.debug) NSLog(@"[%@ %@] fetching all %@ (i.e., no predicate)", NSStringFromClass([self class]), NSStringFromSelector(_cmd), self.fetchedResultsController.fetchRequest.entityName);
        }
        NSError *error;
        [self.fetchedResultsController performFetch:&error];
        if (error) NSLog(@"[%@ %@] %@ (%@)", NSStringFromClass([self class]), NSStringFromSelector(_cmd), [error localizedDescription], [error localizedFailureReason]);
    } else {
        if (self.debug) NSLog(@"[%@ %@] no NSFetchedResultsController (yet?)", NSStringFromClass([self class]), NSStringFromSelector(_cmd));
    }
    [self.tableView reloadData];
}

- (void)setFetchedResultsController:(NSFetchedResultsController *)newfrc
{
    NSFetchedResultsController *oldfrc = _fetchedResultsController;
    if (newfrc != oldfrc) {
        _fetchedResultsController = newfrc;
        newfrc.delegate = self;
        if ((!self.title || [self.title isEqualToString:oldfrc.fetchRequest.entity.name]) && (!self.navigationController || !self.navigationItem.title)) {
            self.title = newfrc.fetchRequest.entity.name;
        }
        if (newfrc) {
            if (self.debug) NSLog(@"[%@ %@] %@", NSStringFromClass([self class]), NSStringFromSelector(_cmd), oldfrc ? @"updated" : @"set");
            [self performFetch];
        } else {
            if (self.debug) NSLog(@"[%@ %@] reset to nil", NSStringFromClass([self class]), NSStringFromSelector(_cmd));
            [self.tableView reloadData];
        }
    }
}

#pragma mark - UITableViewDataSource

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [[[self.fetchedResultsController sections] objectAtIndex:section] numberOfObjects];
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    return [[[self.fetchedResultsController sections] objectAtIndex:section] name];
}

- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index
{
    return [self.fetchedResultsController sectionForSectionIndexTitle:title atIndex:index];
}

- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
    return [self.fetchedResultsController sectionIndexTitles];
}

#pragma mark - NSFetchedResultsControllerDelegate

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
    if(!self.reordering){
        if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext) {
            [self.tableView beginUpdates];
            self.beganUpdates = YES;
        }
    }
}

- (void)controller:(NSFetchedResultsController *)controller
  didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex
     forChangeType:(NSFetchedResultsChangeType)type
{
    if(!self.reordering){
        if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
        {
            switch(type)
            {
                case NSFetchedResultsChangeInsert:
                    [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                    break;

                case NSFetchedResultsChangeDelete:
                    [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                    break;
            }
        }
    }
}


- (void)controller:(NSFetchedResultsController *)controller
   didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath
     forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath
{
    if(!self.reordering){
        if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
        {
            switch(type)
            {
                case NSFetchedResultsChangeInsert:
                    [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
                    break;

                case NSFetchedResultsChangeDelete:
                    [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                    break;

                case NSFetchedResultsChangeUpdate:
                    [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                    break;

                case NSFetchedResultsChangeMove:
                    [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                    [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
                    break;
            }
        }
    }
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
    if(!self.reordering){
        if (self.beganUpdates) [self.tableView endUpdates];
    }
}

- (void)endSuspensionOfUpdatesDueToContextChanges
{
    _suspendAutomaticTrackingOfChangesInManagedObjectContext = NO;
}

- (void)setSuspendAutomaticTrackingOfChangesInManagedObjectContext:(BOOL)suspend
{
    if (suspend) {
        _suspendAutomaticTrackingOfChangesInManagedObjectContext = YES;
    } else {
        [self performSelector:@selector(endSuspensionOfUpdatesDueToContextChanges) withObject:0 afterDelay:0];
    }
}

- (void)displayData {
    //Total cost/month will be fetched and formatted
    NSNumberFormatter *numberFormatter =[[NSNumberFormatter alloc] init];
    [numberFormatter setNumberStyle:NSNumberFormatterCurrencyStyle];

    self.sumLabel.text = [[DatabaseFetches budgetPerMonthForManagedObjectContext:self.budgetDatabase.managedObjectContext] getLocalizedCurrencyString];
    [self.tableView deselectRowAtIndexPath:[self.tableView indexPathForSelectedRow] animated:YES];
}

-(void)useDocument
{
    if(![[NSFileManager defaultManager]fileExistsAtPath:[self.budgetDatabase.fileURL path]]){
        [self.budgetDatabase saveToURL:self.budgetDatabase.fileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
            [self setupFetchedResultsController];
            [self displayData]; ******
            //[self initializeDatabaseWithData];
        }];
    } else if (self.budgetDatabase.documentState == UIDocumentStateClosed){
        [self.budgetDatabase openWithCompletionHandler:^(BOOL success){
            [self setupFetchedResultsController];
            [self displayData]; ******
        }];
    } else if (self.budgetDatabase.documentState == UIDocumentStateNormal){
        [self setupFetchedResultsController];
        [self displayData]; ******
    }
}