save:初始NSManagedObjectContext NSFetchedResultsController设置NSManagedObjectContext，其过滤boolean＆＃34; show＆＃34;属性。NSManagedObjectContext和save:。我希望这会导致我的NSFetchedResultsController致电NSFetchedResultsControllerDelegate controllerDidChangeContent:。我从来没有接到那个电话。 NSFetchedResultsController with predicate ignores changes merged from different NSManagedObjectContext accepted answer表示除controllerDidChangeContent:之外，我应该收到NSManagedObjectContextObjectsDidChangeNotification，但我也没有收到。{/ p >
下面列出了完整的代码示例on github。 I've filed a radar with Apple
@interface HJBFoo : NSManagedObject
@property (nonatomic, retain) NSString *name;
@property (nonatomic, retain) NSNumber *show;
@end
@interface HJBAppDelegate () <NSFetchedResultsControllerDelegate>
@property (nonatomic, strong) NSPersistentStoreCoordinator *persistentStoreCoordinator;
@property (nonatomic, strong) NSManagedObjectContext *initialManagedObjectContext;
@property (nonatomic, strong) NSManagedObjectContext *fetchedResultsControllerManagedObjectContext;
@property (nonatomic, strong) NSFetchedResultsController *fetchedResultsController;
@end
@implementation HJBAppDelegate
#pragma mark - UIApplicationDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.window.backgroundColor = [UIColor whiteColor];
self.window.rootViewController = [UIViewController new];
NSAttributeDescription *nameAttributeDescription = [NSAttributeDescription new];
[nameAttributeDescription setAttributeType:NSStringAttributeType];
[nameAttributeDescription setIndexed:NO];
[nameAttributeDescription setOptional:NO];
[nameAttributeDescription setName:@"name"];
NSAttributeDescription *showAttributeDescription = [NSAttributeDescription new];
[showAttributeDescription setAttributeType:NSBooleanAttributeType];
[showAttributeDescription setIndexed:YES];
[showAttributeDescription setOptional:NO];
[showAttributeDescription setName:@"show"];
NSEntityDescription *fooEntityDescription = [NSEntityDescription new];
[fooEntityDescription setManagedObjectClassName:@"HJBFoo"];
[fooEntityDescription setName:@"HJBFoo"];
[fooEntityDescription setProperties:@[
nameAttributeDescription,
showAttributeDescription,
]];
NSManagedObjectModel *managedObjectModel = [NSManagedObjectModel new];
[managedObjectModel setEntities:@[
fooEntityDescription,
]];
self.persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:managedObjectModel];
NSError *error = nil;
if ([self.persistentStoreCoordinator addPersistentStoreWithType:NSInMemoryStoreType
configuration:nil
URL:nil
options:nil
error:&error]) {
self.initialManagedObjectContext = [NSManagedObjectContext new];
[self.initialManagedObjectContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];
HJBFoo *foo1 = [NSEntityDescription insertNewObjectForEntityForName:@"HJBFoo"
inManagedObjectContext:self.initialManagedObjectContext];
foo1.name = @"1";
foo1.show = @YES;
HJBFoo *foo2 = [NSEntityDescription insertNewObjectForEntityForName:@"HJBFoo"
inManagedObjectContext:self.initialManagedObjectContext];
foo2.name = @"2";
foo2.show = @NO;
error = nil;
if ([self.initialManagedObjectContext save:&error]) {
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"HJBFoo"];
[fetchRequest setReturnsObjectsAsFaults:NO];
error = nil;
NSArray *initialFoos = [self.initialManagedObjectContext executeFetchRequest:fetchRequest
error:&error];
if (initialFoos) {
NSLog(@"Initial: %@", initialFoos);
self.fetchedResultsControllerManagedObjectContext = [NSManagedObjectContext new];
[self.fetchedResultsControllerManagedObjectContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];
NSFetchRequest *shownFetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"HJBFoo"];
[shownFetchRequest setPredicate:[NSPredicate predicateWithFormat:@"show == YES"]];
[shownFetchRequest setSortDescriptors:@[
[NSSortDescriptor sortDescriptorWithKey:@"name"
ascending:YES],
]];
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:shownFetchRequest
managedObjectContext:self.fetchedResultsControllerManagedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
self.fetchedResultsController.delegate = self;
error = nil;
if ([self.fetchedResultsController performFetch:&error]) {
NSLog(@"Initial fetchedObjects: %@", [self.fetchedResultsController fetchedObjects]);
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(managedObjectContextDidSave:)
name:NSManagedObjectContextDidSaveNotification
object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(managedObjectContext2ObjectsDidChange:)
name:NSManagedObjectContextObjectsDidChangeNotification
object:self.fetchedResultsControllerManagedObjectContext];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.5 * NSEC_PER_SEC),
dispatch_get_main_queue(),
^(void){
NSManagedObjectContext *managedObjectContext3 = [NSManagedObjectContext new];
[managedObjectContext3 setPersistentStoreCoordinator:self.persistentStoreCoordinator];
NSFetchRequest *foo2FetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"HJBFoo"];
[foo2FetchRequest setFetchLimit:1];
[foo2FetchRequest setPredicate:[NSPredicate predicateWithFormat:@"name == %@",
@"2"]];
NSError *editingError = nil;
NSArray *editingFoos = [managedObjectContext3 executeFetchRequest:foo2FetchRequest
error:&editingError];
if (editingFoos) {
HJBFoo *editingFoo2 = [editingFoos objectAtIndex:0];
editingFoo2.show = @YES;
editingError = nil;
if ([managedObjectContext3 save:&editingError]) {
NSLog(@"Save succeeded. Expected (in order) managedObjectContextDidSave, controllerDidChangeContent, managedObjectContext2ObjectsDidChange");
} else {
NSLog(@"Editing save failed: %@ %@", [error localizedDescription], [error userInfo]);
}
} else {
NSLog(@"Editing fetch failed: %@ %@", [error localizedDescription], [error userInfo]);
}
});
} else {
NSLog(@"Failed initial fetch: %@ %@", [error localizedDescription], [error userInfo]);
}
} else {
NSLog(@"Failed to performFetch: %@ %@", [error localizedDescription], [error userInfo]);
}
} else {
NSLog(@"Failed to save initial state: %@ %@", [error localizedDescription], [error userInfo]);
}
} else {
NSLog(@"Failed to add persistent store: %@ %@", [error localizedDescription], [error userInfo]);
}
[self.window makeKeyAndVisible];
return YES;
}
#pragma mark - NSFetchedResultsControllerDelegate
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
NSLog(@"controllerDidChangeContent: %@",
[self.fetchedResultsController fetchedObjects]);
}
#pragma mark - notifications
- (void)managedObjectContextDidSave:(NSNotification *)notification {
NSManagedObjectContext *managedObjectContext = [notification object];
if (([managedObjectContext persistentStoreCoordinator] == self.persistentStoreCoordinator) &&
(managedObjectContext != self.fetchedResultsControllerManagedObjectContext)) {
NSLog(@"managedObjectContextDidSave: %@", notification);
[self.fetchedResultsControllerManagedObjectContext mergeChangesFromContextDidSaveNotification:notification];
}
}
- (void)managedObjectContext2ObjectsDidChange:(NSNotification *)notification {
NSLog(@"managedObjectContext2ObjectsDidChange: %@", notification);
}
@end
@implementation HJBFoo
@dynamic name;
@dynamic show;
@end
答案 0 :(得分：17)
在我看来，应用NSFetchedResultsController with predicate ignores changes merged from different NSManagedObjectContext中的修复/解决方法也可以解决您的问题。您的managedObjectContextDidSave方法将如下所示：
- (void)managedObjectContextDidSave:(NSNotification *)notification {
NSManagedObjectContext *managedObjectContext = [notification object];
if (([managedObjectContext persistentStoreCoordinator] == self.persistentStoreCoordinator) &&
(managedObjectContext != self.fetchedResultsControllerManagedObjectContext)) {
NSLog(@"managedObjectContextDidSave: %@", notification);
// Fix/workaround from https://stackoverflow.com/questions/3923826/nsfetchedresultscontroller-with-predicate-ignores-changes-merged-from-different/3927811#3927811
for(NSManagedObject *object in [[notification userInfo] objectForKey:NSUpdatedObjectsKey]) {
[[self.fetchedResultsControllerManagedObjectContext objectWithID:[object objectID]] willAccessValueForKey:nil];
}
[self.fetchedResultsControllerManagedObjectContext mergeChangesFromContextDidSaveNotification:notification];
}
}
并且NSLog输出看起来像预期的那样：
Initial: (
"<HJBFoo: 0xaa19670> (entity: HJBFoo; id: 0xaa1afd0 <x-coredata://07E97098-E32D-45F6-9AB4-F9DAB9B0AC1A/HJBFoo/p2> ; data: {\n name = 1;\n show = 1;\n})",
"<HJBFoo: 0xaa1a200> (entity: HJBFoo; id: 0xaa1af50 <x-coredata://07E97098-E32D-45F6-9AB4-F9DAB9B0AC1A/HJBFoo/p1> ; data: {\n name = 2;\n show = 0;\n})"
)
Initial fetchedObjects: (
"<HJBFoo: 0x74613f0> (entity: HJBFoo; id: 0xaa1afd0 <x-coredata://07E97098-E32D-45F6-9AB4-F9DAB9B0AC1A/HJBFoo/p2> ; data: <fault>)"
)
managedObjectContextDidSave: NSConcreteNotification 0xaa1f480 {name = NSManagingContextDidSaveChangesNotification; object = <NSManagedObjectContext: 0xaa1ed90>; userInfo = {
inserted = "{(\n)}";
updated = "{(\n <HJBFoo: 0xaa1f2d0> (entity: HJBFoo; id: 0xaa1af50 <x-coredata://07E97098-E32D-45F6-9AB4-F9DAB9B0AC1A/HJBFoo/p1> ; data: {\n name = 2;\n show = 1;\n})\n)}";
}}
Save succeeded. Expected (in order) managedObjectContextDidSave, controllerDidChangeContent, managedObjectContext2ObjectsDidChange
controllerDidChangeContent: (
"<HJBFoo: 0x74613f0> (entity: HJBFoo; id: 0xaa1afd0 <x-coredata://07E97098-E32D-45F6-9AB4-F9DAB9B0AC1A/HJBFoo/p2> ; data: {\n name = 1;\n show = 1;\n})",
"<HJBFoo: 0xaa1f9c0> (entity: HJBFoo; id: 0xaa1af50 <x-coredata://07E97098-E32D-45F6-9AB4-F9DAB9B0AC1A/HJBFoo/p1> ; data: {\n name = 2;\n show = 1;\n})"
)
managedObjectContext2ObjectsDidChange: NSConcreteNotification 0xaa1fbb0 {name = NSObjectsChangedInManagingContextNotification; object = <NSManagedObjectContext: 0x745fa50>; userInfo = {
managedObjectContext = "<NSManagedObjectContext: 0x745fa50>";
refreshed = "{(\n <HJBFoo: 0xaa1f9c0> (entity: HJBFoo; id: 0xaa1af50 <x-coredata://07E97098-E32D-45F6-9AB4-F9DAB9B0AC1A/HJBFoo/p1> ; data: {\n name = 2;\n show = 1;\n})\n)}";
}}
所以发生以下事情：
managedObjectContext3中进行并保存。NSManagedObjectContextDidSaveNotification并且调用了managedObjectContextDidSave:。此通知包含在后台上下文中更新的对象。调用
[self.fetchedResultsControllerManagedObjectContext mergeChangesFromContextDidSaveNotification:notification];
现在没有做任何事情，因为更新的对象尚未加载到fetchedResultsControllerManagedObjectContext或是一个错误。特别是，此上下文不会发布NSManagedObjectContextObjectsDidChangeNotification，并且获取的结果控制器不会更新。
willAccessValueForKey会强制fetchedResultsControllerManagedObjectContext加载这些对象并触发故障。调用
[self.fetchedResultsControllerManagedObjectContext mergeChangesFromContextDidSaveNotification:notification];
之后实际更新fetchedResultsControllerManagedObjectContext。
NSManagedObjectContextObjectsDidChangeNotification，并且获取的结果控制器调用相应的委托函数。