我正在调用来自Web服务的数据，将其存储到CoreData中，然后将其放入我用来填充tableview的数组中。当视图加载时，我将删除CoreData中实体中保存的所有数据，因为来自Web服务的数据将经常更新并且可能来自多个平台。如果没有删除代码，一切正常（除了旧数据会在CoreData中构建），但是一旦我实现deleteEntityData调用，我就会在模拟器上发生这种奇怪的事情。数据出现然后立即消失，就像在tableview加载之前和之后调用删除代码一样。使用NSLogs检查代码似乎是以正确的顺序触发（并且至少根据NSLogs，删除代码没有触发两次）..
这是一个截屏视频的链接，以便您可以看到我在模拟器上看到的内容。
我tableview中主要方法的代码如下：
- (void)viewDidLoad{
[super viewDidLoad];
[self setUpData];
}
- (void) deleteEntityData {
//Delete All Old Exlpore View Entities in Core Data
NSLog(@"Delete code being called");
NSManagedObjectContext *context = [self managedObjectContext];
NSFetchRequest *fetch = [[NSFetchRequest alloc] init];
[fetch setEntity:[NSEntityDescription entityForName:@"HomeView" inManagedObjectContext:context]];
[fetch setIncludesPropertyValues:NO];
NSError *error = nil;
NSArray *entities = [context executeFetchRequest:fetch error:&error];
for (NSManagedObject * exploreView in entities) {
[context deleteObject:exploreView];
}
if (![context save:&error]) {
NSLog(@"Can't Save! %@ %@", error, [error localizedDescription]);
};
[self.tableView reloadData];
}
- (void) setUpData {
//Initialize AFHTTPRequestOperationManager with Dribbble API base URL
_operationManager = [[AFHTTPRequestOperationManager alloc] initWithBaseURL:[NSURL URLWithString:@"http://www.karmo.com/home/news"]];
[_operationManager GET:@"?user_id=XXXX" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
//Success - Runs if connection is made and data recieved
[self deleteEntityData];
//Extrat parsed JSON file into objects to prepare for Core Data import -- Should verify if I can skip and go directly into Core Data
NSManagedObjectContext *context = [self managedObjectContext];
for (int i = 0; i < [[responseObject valueForKey:@"userBeliefs"] count]; i++) {
NSString * type = @"user";
NSString * userFirstName = [[[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"user"] valueForKey:@"firstName"];
NSString * userLastName = [[[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"user"] valueForKey:@"lastName"];
NSString * userID = [[[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"user"] valueForKey:@"_id"];
NSString * topicID = [[[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"topic"] valueForKey:@"_id"];
NSString * title = [[[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"topic"] valueForKey:@"title"];
NSString * vote = [[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"vote"];
NSString * voice = [[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"voice"];
NSString * beliefID = [[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"_id"];
NSNumber * nPoints = @([[[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"nPoints"]intValue]);
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"];
NSDate *updatedAt = [dateFormat dateFromString:[[[responseObject valueForKey:@"userBeliefs"]objectAtIndex:i] valueForKey:@"updatedAt"]];
NSManagedObject *newHome = [NSEntityDescription insertNewObjectForEntityForName:@"HomeView" inManagedObjectContext:context];
[newHome setValue:type forKey:@"type"];
[newHome setValue:userFirstName forKey:@"userFirstName"];
[newHome setValue:userLastName forKey:@"userLastName"];
[newHome setValue:userID forKey:@"userID"];
[newHome setValue:topicID forKey:@"topicID"];
[newHome setValue:title forKey:@"title"];
[newHome setValue:vote forKey:@"vote"];
[newHome setValue:voice forKey:@"voice"];
[newHome setValue:beliefID forKey:@"beliefID"];
[newHome setValue:nPoints forKey:@"nPoints"];
[newHome setValue:updatedAt forKey:@"updatedAt"];
}
for (int i = 0; i < [[responseObject valueForKey:@"followeeBeliefs"] count]; i++) {
NSUInteger arrayCount = [[[responseObject valueForKey:@"followeeBeliefs"] objectAtIndex:i] count];
NSUInteger subtract = 2;
NSUInteger finalCount = arrayCount - subtract;
for (int ii = 0; ii < finalCount; ii++) {
NSString * type = @"followee";
NSString * followeeUserID = [[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:@"followee"];
NSString * connectionID = [[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:@"_id"];
NSString * userFirstName = [[[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"user"] valueForKey:@"firstName"];
NSString * userLastName = [[[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"user"] valueForKey:@"lastName"];
NSString * userID = [[[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"user"] valueForKey:@"_id"];
NSString * topicID = [[[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"topic"] valueForKey:@"_id"];
NSString * title = [[[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"topic"] valueForKey:@"title"];
NSString * vote = [[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"vote"];
NSString * voice = [[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"voice"];
NSString * beliefID = [[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"_id"];
NSNumber * nPoints = @([[[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"nPoints"]intValue]);
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"];
NSDate *updatedAt = [dateFormat dateFromString:[[[[responseObject valueForKey:@"followeeBeliefs"]objectAtIndex:i] valueForKey:[@(ii) stringValue]] valueForKey:@"updatedAt"]];
NSManagedObject *newHome = [NSEntityDescription insertNewObjectForEntityForName:@"HomeView" inManagedObjectContext:context];
[newHome setValue:type forKey:@"type"];
[newHome setValue:followeeUserID forKey:@"followeeUserID"];
[newHome setValue:connectionID forKey:@"connectionID"];
[newHome setValue:userFirstName forKey:@"userFirstName"];
[newHome setValue:userLastName forKey:@"userLastName"];
[newHome setValue:userID forKey:@"userID"];
[newHome setValue:topicID forKey:@"topicID"];
[newHome setValue:title forKey:@"title"];
[newHome setValue:vote forKey:@"vote"];
[newHome setValue:voice forKey:@"voice"];
[newHome setValue:beliefID forKey:@"beliefID"];
[newHome setValue:nPoints forKey:@"nPoints"];
[newHome setValue:updatedAt forKey:@"updatedAt"];
}
}
for (int i = 0; i < [[responseObject valueForKey:@"topics"] count]; i++) {
NSString * type = @"topic";
NSString * topicID = [[[responseObject valueForKey:@"topics"]objectAtIndex:i] valueForKey:@"_id"];
NSString * category = [[[responseObject valueForKey:@"topics"]objectAtIndex:i] valueForKey:@"category"];
NSString * title = [[[responseObject valueForKey:@"topics"]objectAtIndex:i] valueForKey:@"title"];
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"];
NSDate *updatedAt = [dateFormat dateFromString:[[[responseObject valueForKey:@"topics"]objectAtIndex:i] valueForKey:@"updatedAt"]];
NSString * eventTitle = [[[[responseObject valueForKey:@"topics"]objectAtIndex:i] valueForKey:@"lastEvent"] valueForKey:@"title"];
NSString * eventBody = [[[[responseObject valueForKey:@"topics"]objectAtIndex:i] valueForKey:@"lastEvent"] valueForKey:@"body"];
NSString * eventID = [[[[responseObject valueForKey:@"topics"]objectAtIndex:i] valueForKey:@"lastEvent"] valueForKey:@"_id"];
NSDate * eventUpdatedAt = [dateFormat dateFromString:[[[[responseObject valueForKey:@"topics"]objectAtIndex:i] valueForKey:@"lastEvent"] valueForKey:@"updatedAt"]];
NSDate * eventCreatedAt = [dateFormat dateFromString:[[[[responseObject valueForKey:@"topics"]objectAtIndex:i] valueForKey:@"lastEvent"] valueForKey:@"updatedAt"]];
NSManagedObject *newHome = [NSEntityDescription insertNewObjectForEntityForName:@"HomeView" inManagedObjectContext:context];
[newHome setValue:type forKey:@"type"];
[newHome setValue:topicID forKey:@"topicID"];
[newHome setValue:category forKey:@"category"];
[newHome setValue:title forKey:@"title"];
[newHome setValue:updatedAt forKey:@"updatedAt"];
[newHome setValue:eventTitle forKey:@"eventTitle"];
[newHome setValue:eventBody forKey:@"eventBody"];
[newHome setValue:eventID forKey:@"eventID"];
[newHome setValue:eventUpdatedAt forKey:@"eventUpdatedAt"];
[newHome setValue:eventCreatedAt forKey:@"eventCreatedAt"];
}
NSError *error = nil;
if (![context save:&error]) {
NSLog(@"Can't Save! %@ %@", error, [error localizedDescription]);
}
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
//Failure
NSLog(@"Failed to fetch shots from Karmo API!");
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Unable to Connect"
message:@"We were not able to connect to the karmo database. Some data may be out of date."
delegate:self
cancelButtonTitle:@"Ok"
otherButtonTitles: nil];
[alert show];
} ];
[self fetchData];}
- (void) fetchData {
[homeSortData removeAllObjects];
[homeTableData removeAllObjects];
// Fetch the recipes from persistent data store
NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"HomeView"];
homeSortData = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];
NSSortDescriptor *dateDescriptor = [NSSortDescriptor
sortDescriptorWithKey:@"updatedAt"
ascending:YES];
NSMutableArray * descriptors = [[NSArray arrayWithObjects:dateDescriptor, nil]mutableCopy];
homeTableData = [[homeSortData sortedArrayUsingDescriptors:descriptors]mutableCopy];
[self.tableView reloadData];}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
if ([[[homeTableData objectAtIndex:indexPath.row] valueForKey:@"type"] isEqualToString:@"topic"]) {
HomeTopicUpdateTableViewCell *topicCell = (HomeTopicUpdateTableViewCell *) [tableView dequeueReusableCellWithIdentifier:@"Topic" forIndexPath:indexPath];
NSDate * topicDate = [[homeTableData objectAtIndex:indexPath.row] valueForKey:@"updatedAt"];
NSString *currentDateString;
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"];
currentDateString = [dateFormat stringFromDate:[NSDate date]];
NSDate *currentDate = [dateFormat dateFromString:currentDateString];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *dayComponents = [gregorianCalendar components:NSDayCalendarUnit
fromDate:topicDate
toDate:currentDate
options:0];
NSString *dayDifference = [NSString stringWithFormat:@"%@d", [@([dayComponents day]) stringValue]];
[topicCell.title setText:[[homeTableData objectAtIndex:indexPath.row] valueForKey:@"title"]];
[topicCell.days setText:dayDifference];
[topicCell.eventTitle setText:[[homeTableData objectAtIndex:indexPath.row]valueForKey:@"eventTitle"]];
return topicCell;
}
if ([[[homeTableData objectAtIndex:indexPath.row] valueForKey:@"type"] isEqualToString:@"user"]) {
HomeBeliefTableViewCell *userCell = (HomeBeliefTableViewCell *) [tableView dequeueReusableCellWithIdentifier:@"User" forIndexPath:indexPath];
NSDate * topicDate = [[homeTableData objectAtIndex:indexPath.row] valueForKey:@"updatedAt"];
NSString *currentDateString;
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"];
currentDateString = [dateFormat stringFromDate:[NSDate date]];
NSDate *currentDate = [dateFormat dateFromString:currentDateString];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *dayComponents = [gregorianCalendar components:NSDayCalendarUnit
fromDate:topicDate
toDate:currentDate
options:0];
NSString *dayDifference = [NSString stringWithFormat:@"%@d", [@([dayComponents day]) stringValue]];
NSString *pointCount = [[[homeTableData objectAtIndex:indexPath.row] valueForKey: @"nPoints"]stringValue];
[userCell.title setText:[[homeTableData objectAtIndex:indexPath.row] valueForKey:@"title"]];
[userCell.belief setText:[[homeTableData objectAtIndex:indexPath.row] valueForKey:@"voice"]];
[userCell.points setText:pointCount];
[userCell.profileName setText:@"Me"];
[userCell.days setText:dayDifference];
return userCell;
} else {
HomeFolloweeBeliefTableViewCell *followeeCell = (HomeFolloweeBeliefTableViewCell *) [tableView dequeueReusableCellWithIdentifier:@"Followee" forIndexPath:indexPath];
NSDate * topicDate = [[homeTableData objectAtIndex:indexPath.row] valueForKey:@"updatedAt"];
NSString *currentDateString;
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"];
currentDateString = [dateFormat stringFromDate:[NSDate date]];
NSDate *currentDate = [dateFormat dateFromString:currentDateString];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *dayComponents = [gregorianCalendar components:NSDayCalendarUnit
fromDate:topicDate
toDate:currentDate
options:0];
NSString *dayDifference = [NSString stringWithFormat:@"%@d", [@([dayComponents day]) stringValue]];
NSString *fullName = [NSString stringWithFormat:@"%@ %@",[[homeTableData objectAtIndex:indexPath.row] valueForKey:@"userFirstName"],[[homeTableData objectAtIndex:indexPath.row] valueForKey:@"userLastName"]];
NSString *pointCount = [[[homeTableData objectAtIndex:indexPath.row] valueForKey: @"nPoints"]stringValue];
[followeeCell.title setText:[[homeTableData objectAtIndex:indexPath.row] valueForKey:@"title"]];
[followeeCell.belief setText:[[homeTableData objectAtIndex:indexPath.row] valueForKey:@"voice"]];
[followeeCell.profileName setText:fullName];
[followeeCell.days setText:dayDifference];
return followeeCell;}}
答案 0 :(得分：0)
似乎在＆＃34;成功＆＃34;阻止您的网络呼叫，在解析响应并将其保存在核心数据中后，您不会调用[self.tableView reloadData]。
在deleteEntityData中调用reloadData（这就是你看到数据消失的原因）和fetchData，但fetchData最有可能在成功块完成之前执行，因此数据尚未保存在核心数据中。如果保存到核心数据后成功阻止，则调用[self.tableView reloadData，或者将调用移动到fetchData到成功块的末尾（也在保存核心数据上下文之后）