iOS 10和Swift 3

假设您的实体名称是“Photo”，并且您创建了一个CoreDataStack类…

 func clearData() {
        do {            
            let context = CoreDataStack.sharedInstance.persistentContainer.viewContext
            let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Photo")
            do {
                let objects  = try context.fetch(fetchRequest) as? [NSManagedObject]
                _ = objects.map{$0.map{context.delete($0)}}
                CoreDataStack.sharedInstance.saveContext()
            } catch let error {
                print("ERROR DELETING : \(error)")
            }
        }
    }

这里有一个很好的教程，教你如何使用CoreData以及如何使用这个方法。 https://medium.com/compileswift/parsing-json-response-and-save-it-in-coredata-step-by-step-fb58fc6ce16f#.1tu6kt8qb

删除持久存储文件并设置一个新的持久存储协调器?

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];
}

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];
}

iOS 10+的更新解决方案

使用NSBatchDeleteRequest删除实体中的所有对象，而不必将它们加载到内存中或遍历它们。

// create the delete request for the specified entity
let fetchRequest: NSFetchRequest<NSFetchRequestResult> = MyEntity.fetchRequest()
let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)

// get reference to the persistent container
let persistentContainer = (UIApplication.shared.delegate as! AppDelegate).persistentContainer

// perform the delete
do {
    try persistentContainer.viewContext.execute(deleteRequest)
} catch {
    print(error.localizedDescription)
}

此代码已更新为iOS 10和Swift 3。如果你需要支持iOS 9，请看这个问题。

来源:

核心数据:删除实体的所有实例的最快方法(包括Objective-C代码) Core Data的新内容(WWDC 2015视频) Core Data的新内容(WWDC 2016视频) 如何在iOS 10中使用核心数据 Core Data Swift 3.0有什么新功能

您还可以查找所有实体名称，并按名称删除它们。它是一个较长的版本，但工作得很好，这样你就不必使用持久性存储

 - (void)clearCoreData
{
NSError *error;
NSEntityDescription *des = [NSEntityDescription entityForName:@"Any_Entity_Name" inManagedObjectContext:_managedObjectContext];
NSManagedObjectModel *model = [des managedObjectModel];
NSArray *entityNames = [[model entities] valueForKey:@"name"];

for (NSString *entityName in entityNames){

    NSFetchRequest *deleteAll = [NSFetchRequest fetchRequestWithEntityName:entityName];
    NSArray *matches = [self.database.managedObjectContext executeFetchRequest:deleteAll error:&error];

}
    if (matches.count > 0){
        for (id obj in matches){

            [_managedObjectContext deleteObject:obj];
        }
       [self.database.managedObjectContext save:&error];
    }
}

对于“Any_Entity_Name”，只需要给出任何一个实体的名称，我们只需要找出实体的实体描述。ValueForKey@"name"将返回所有实体名称。最后，别忘了保存。