在我试着问两次并解释自己后，我做了一个挖掘，我想我现在可以更好地解释我的问题了：
1）我正在使用核心数据保存到NSManagedObjects：CoreDataTrap＆amp; CoreDataAllTraps。
第一次，我正在解析一个大的xml，然后转换为数组，然后将细节添加到CoreDataAllTraps，这个操作很顺利，因为我做了一个日志。
2）然后，为了测试，我正在获取所有记录并记录它们的总数。
这些功能可以为我提供正确的记录数。 3）然后只是初始化一些变量。
4）然后初始化我的四叉树。
这让我回到了我的断言错误。
错误：fetchedObjects没有记录。
5）然后，使用核心数据的所有其他函数当然会给我错误，因为没有数据。
相关（编号）代码：
1:
---
- (void)addOrUpdateTrap:(Traps*)trapObject
{
NSManagedObjectContext *context = generateManagedObjectContext();
int trapID = trapObject.getTrapID;
CoreDataAllTraps *trapEntity = nil;
NSError *error = nil;
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:kCORE_DATA_ALL_TRAPS_ENTITY];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"trapID == %d", trapID];
[fetchRequest setPredicate:predicate];
NSArray *results = [context executeFetchRequest:fetchRequest error:&error];
if (results == nil)
{
// Handle error
}
else if (results.count == 0)
{
// Nothing to update, add new trap
// Create a new record (row)
trapEntity = [NSEntityDescription insertNewObjectForEntityForName:kCORE_DATA_ALL_TRAPS_ENTITY inManagedObjectContext:context];
}
else
{
trapEntity = results[0]; // There should be only one object for the ID.
}
if (trapEntity != nil)
{
// Set properties for new or existing object ...
// Int
[trapEntity setTrapID:[NSNumber numberWithInt:trapObject.getTrapID]];
[trapEntity setType:[NSNumber numberWithInt:trapObject.getTrapType]];
[trapEntity setDist:[NSNumber numberWithInt:trapObject.getTrapDistanceToCar]];
[trapEntity setDist_to_close_point:[NSNumber numberWithInt:trapObject.getTrapDistanceToClosePoint]];
[trapEntity setActive:[NSNumber numberWithInt:trapObject.isActive]];
[trapEntity setAlert:[NSNumber numberWithInt:trapObject.isAlert]];
[trapEntity setAlarmDistance:[NSNumber numberWithInt:trapObject.alarmDistance]];
[trapEntity setRoadNumber:[NSNumber numberWithInt:trapObject.roadNumber]];
[trapEntity setPolys:[NSNumber numberWithInt:trapObject.polygons]];
[trapEntity setEnter_to_area:[NSNumber numberWithInt:trapObject.getTrapEnterToArea]];
// Double
[trapEntity setLat:[NSNumber numberWithDouble:trapObject.getTrapLat]];
[trapEntity setLon:[NSNumber numberWithDouble:trapObject.getTrapLon]];
[trapEntity setClose_point_lat:[NSNumber numberWithDouble:trapObject.getTrapClosePointLat]];
[trapEntity setClose_point_lon:[NSNumber numberWithDouble:trapObject.getTrapClosePointLon]];
// NSString
[trapEntity setLastTrapAlarm:[NSString stringWithFormat:@"%li", trapObject.getTrapLastAlarm]];
[trapEntity setPoly0:trapObject.getTrapPolygonA];
[trapEntity setPoly1: trapObject.getTrapPolygonB];
[trapEntity setPoly2: trapObject.getTrapPolygonC];
[trapEntity setPolygonAzimut1: trapObject.getTrapPolygonAzimuthA];
[trapEntity setPolygonAzimut2: trapObject.getTrapPolygonAzimuthB];
[trapEntity setPolygonAzimut3: trapObject.getTrapPolygonAzimuthC];
[trapEntity setDesc: trapObject.getTrapDesc];
// etc. for all properties ...
error = nil;
if ([context save:&error] == NO) {
NSLog(@"%s error saving: %@\n%@", __PRETTY_FUNCTION__, error.localizedDescription, error.userInfo);
}
else {
[context reset];
}
}
}
2:
---
- (void)saveArray:(NSArray*)array
{
kNETROADS_CONTEXT.arrayOfAllTraps = self.arrayOfAllTraps = array.mutableCopy;
NSLog(@"Total number of traps: %d", self.arrayOfAllTraps.count);
NSManagedObjectContext *context = generateManagedObjectContext();
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:kCORE_DATA_ALL_TRAPS_ENTITY inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSError *error = nil;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
NSLog(@"TrapService - fetchedObjects.count: %d", fetchedObjects.count);
if (fetchedObjects == nil || fetchedObjects.count == 0) {
NSLog(@"saveArray - localizedDescription: %@, userInfo: %@", error.localizedDescription, error.userInfo);
}
[self readArray];
}
- (void)readArray
{
NSManagedObjectContext *context = generateManagedObjectContext();
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:kCORE_DATA_ALL_TRAPS_ENTITY inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSError *error = nil;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
NSLog(@"readArray - fetchedObjects.count: %d", fetchedObjects.count);
if (fetchedObjects == nil || fetchedObjects.count == 0) {
NSLog(@"readArray - localizedDescription: %@, userInfo: %@", error.localizedDescription, error.userInfo);
}
}
3:
---
- (void)initVariables
{
db = [[DataBase alloc] init];
//dbat = [[DataBaseAllTraps alloc] init];
dbat = [DataBaseAllTraps getInstance];
kRECEIVER_CONTEXT.db = [[DataBase alloc] init];
[db deleteTrapsTable];
[dbat deleteTrapsTable];
self.dictAddUserLocations = [[NSMutableDictionary alloc] init];
self.arrayOfAllTraps = [Netroads sharedInstance].arrayOfAllTraps;
self.arrayOfLocations = [[NSMutableArray alloc] init];
self.firstOnLocationChanged = YES;
self.mLocation = [CLLocation new];
self.mLastLocation = [CLLocation new];
self.globalLocation = [CLLocation new];
self.lastGlobalLocation = [CLLocation new];
self.myLocations = [[NSMutableArray alloc] init];
self.accuracy = @"N/A";
self.closeTrap = [[Traps alloc] init];
self.notification = [NSNotificationCenter defaultCenter];
// [self.notification addObserver:self selector:@selector(onReceive:) name:kSend_To_Receiver_Notification object:nil];
}
4:
---
- (void)initializeQuadTree
{
self.qTree = [[QuadTree alloc] init];
BOOL success = YES;
NSManagedObjectContext *context = generateManagedObjectContext();
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:kCORE_DATA_ALL_TRAPS_ENTITY inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSError *error = nil;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil || fetchedObjects.count == 0)
{
NSLog(@"initializeQuadTree - localizedDescription: %@, userInfo: %@", error.localizedDescription, error.userInfo);
success = NO;
}
NSLog(@"initializeQuadTree - fetchedObjects.count: %d", fetchedObjects.count);
NSAssert(fetchedObjects != nil, @"Error: fetchedObjects = nil");
NSAssert(fetchedObjects.count > 0, @"Error: fetchedObjects have no records.");
if (success)
{
for (CoreDataAllTraps *trap in fetchedObjects)
{
double latitude = trap.lat.doubleValue;
double longitude = trap.lon.doubleValue;
double closePointLat = trap.close_point_lat.doubleValue;
double closePointLon = trap.close_point_lon.doubleValue;
DummyAnnotation *trapAnnotation = [[DummyAnnotation alloc] init];
if (closePointLat != 0.0 || closePointLon != 0.0) trapAnnotation.coordinate = CLLocationCoordinate2DMake(closePointLat, closePointLon);
else trapAnnotation.coordinate = CLLocationCoordinate2DMake(latitude, longitude);
[self.qTree insertObject:trapAnnotation];
}
}
else
{
for (Traps *trap in kNETROADS_CONTEXT.arrayOfAllTraps)
{
double latitude = trap.lat;
double longitude = trap.lon;
double closePointLat = trap.closePointLat;
double closePointLon = trap.closePointLon;
DummyAnnotation *trapAnnotation = [[DummyAnnotation alloc] init];
if (closePointLat != 0.0 || closePointLon != 0.0) trapAnnotation.coordinate = CLLocationCoordinate2DMake(closePointLat, closePointLon);
else trapAnnotation.coordinate = CLLocationCoordinate2DMake(latitude, longitude);
[self.qTree insertObject:trapAnnotation];
}
}
NSLog(@"TOTAL NUMBER OF TRAPS (%s): %i", __PRETTY_FUNCTION__, success?fetchedObjects.count:[Netroads sharedInstance].arrayOfAllTraps.count);
}
附注：
*致电initializeQuadTree后我正在初始化位置经理。
*在位置管理器中，我有一个dispatch_async包含整个代码。
*完成所有初始化后，代码的主要部分通过位置管理器didUpdateLocations发生。
*对于核心数据中的每一个使用，我正在生成新的NSManagedObjectConext，如下所示：
FOUNDATION_EXPORT NSManagedObjectContext *generateManagedObjectContext()
{
NSManagedObjectContext *context = [[NSManagedObjectContext alloc] init];
context.persistentStoreCoordinator = appDelegate.persistentStoreCoordinator;
return context;
}
答案 0 :(得分：2)
[db deleteTrapsTable];
[dbat deleteTrapsTable];
创建表后删除了表