Question

我有一些对象存储在核心数据中。现在我想一次获取所有对象，但是在我完成操作之后，我想从核心数据中仅删除该行/对象。然后再次获取下一行并删除该行，依此类推，直到核心数据为空。（使用好的方法）我的代码将对象存储在核心数据中：

-(BOOL)saveProduct:(AddProduct *)addProduct withImageNSData:(NSData *)imageNSData error:(NSError *)error{
    NSManagedObject *object = [NSEntityDescription insertNewObjectForEntityForName:@"Device" inManagedObjectContext:self.managedObjectContext];
    Device *device = (Device *)object;
    [device setValue:addProduct.CurrencyType forKey:@"currencyType"];
    [device setValue:[NSNumber numberWithDouble:addProduct.Latitude] forKey:@"latitude"];
    [device setValue:[NSNumber numberWithDouble:addProduct.Longitude] forKey:@"longitude"];
    [device setValue:[NSNumber numberWithDouble:addProduct.Price] forKey:@"price"];
    return [self.managedObjectContext save:&error];
}

Answer 1

这将获取所有设备并迭代它们，在您完成工作后删除对象：

NSManagedObjectContext *context = self.managedObjectContext;
NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"Device"];

//Fetch all of the Devices
NSError *error;
NSArray *allDevices = [context executeFetchRequest:fetchRequest error:&error];
if (error) {
    NSLog(@"Error fetching devices! %@", error);
    return;
}

for (Device *device in allDevices) {
    // Perform your operation on the device

    [context deleteObject:device];
}
[context save:NULL];

iOS - 核心数据：一次获取和删除一行

1 个答案: