您知道有什么方法可以删除存储在Core Data中的所有条目吗?我的schema应该保持不变;我只想把它重置为空白。
Edit
我希望以编程方式做到这一点,这样用户就可以基本上按下重置按钮。
您知道有什么方法可以删除存储在Core Data中的所有条目吗?我的schema应该保持不变;我只想把它重置为空白。
Edit
我希望以编程方式做到这一点,这样用户就可以基本上按下重置按钮。
当前回答
迅速的解决方案:
class func deleteAllManagedObjects() {
let modelURL = NSBundle.mainBundle().URLForResource("some string", withExtension: "mom")
let mom = NSManagedObjectModel(contentsOfURL: modelURL)
for entityName in mom.entitiesByName.keys {
let fr = NSFetchRequest(entityName: entityName as String)
let a = Utility.managedObjectContext().executeFetchRequest(fr, error: nil) as [NSManagedObject]
for mo in a {
Utility.managedObjectContext().deleteObject(mo)
}
}
Utility.managedObjectContext().save(nil)
}
其他回答
龙道9+ Swift 2
删除所有实体中的所有对象
func clearCoreDataStore() {
let entities = managedObjectModel.entities
for entity in entities {
let fetchRequest = NSFetchRequest(entityName: entity.name!)
let deleteReqest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
do {
try context.executeRequest(deleteReqest)
} catch {
print(error)
}
}
}
这个问题有几个很好的答案。这里有一个简洁的例子。前两行删除sqlite数据库。然后for:循环删除managedObjectContext内存中的任何对象。
NSURL *storeURL = [[(FXYAppDelegate*)[[UIApplication sharedApplication] delegate] applicationDocumentsDirectory] URLByAppendingPathComponent:@"AppName.sqlite"];
[[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil];
for (NSManagedObject *ct in [self.managedObjectContext registeredObjects]) {
[self.managedObjectContext deleteObject:ct];
}
迅速的解决方案:
class func deleteAllManagedObjects() {
let modelURL = NSBundle.mainBundle().URLForResource("some string", withExtension: "mom")
let mom = NSManagedObjectModel(contentsOfURL: modelURL)
for entityName in mom.entitiesByName.keys {
let fr = NSFetchRequest(entityName: entityName as String)
let a = Utility.managedObjectContext().executeFetchRequest(fr, error: nil) as [NSManagedObject]
for mo in a {
Utility.managedObjectContext().deleteObject(mo)
}
}
Utility.managedObjectContext().save(nil)
}
使用这个
+(NSArray *)fetchDataFromEntity:(NSString *)entityName context:(NSManagedObjectContext *)context
{
NSFetchRequest * fetchRequest =[[NSFetchRequest alloc] init];
NSEntityDescription * CategoriesEntity = [NSEntityDescription entityForName:entityName inManagedObjectContext:context];
[fetchRequest setEntity:CategoriesEntity];
NSError * error;
NSInteger count = [context countForFetchRequest:fetchRequest error:&error];
if (count && count>0) {
NSArray * fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects && fetchedObjects.count>0) {
return fetchedObjects;
}else
return nil;
}
else
return nil;
}
+ (void)deleteObjectsOfArray:(NSMutableArray*)ary context:(NSManagedObjectContext *)context {
for (NSManagedObject * obj in ary) {
[context deleteObject:obj];
}
NSError *saveError = nil;
[context save:&saveError];
}
+ (void)deleteEntity:(NSString *)entityName context:(NSManagedObjectContext *)context {
NSArray *listArray = [self fetchDataFromEntity:entityName context:context];
[self deleteObjectsOfArray:[NSMutableArray arrayWithArray:listArray] context:context];
}
如果需要删除所有对象且不删除备份文件,可以使用以下方法:
- (void)deleteAllObjectsInContext:(NSManagedObjectContext *)context
usingModel:(NSManagedObjectModel *)model
{
NSArray *entities = model.entities;
for (NSEntityDescription *entityDescription in entities) {
[self deleteAllObjectsWithEntityName:entityDescription.name
inContext:context];
}
}
- (void)deleteAllObjectsWithEntityName:(NSString *)entityName
inContext:(NSManagedObjectContext *)context
{
NSFetchRequest *fetchRequest =
[NSFetchRequest fetchRequestWithEntityName:entityName];
fetchRequest.includesPropertyValues = NO;
fetchRequest.includesSubentities = NO;
NSError *error;
NSArray *items = [context executeFetchRequest:fetchRequest error:&error];
for (NSManagedObject *managedObject in items) {
[context deleteObject:managedObject];
NSLog(@"Deleted %@", entityName);
}
}
注意它可能非常慢(取决于对象图中有多少对象)。