ios - 无法更新从未插入的对象

Question

我创建一个类别对象并保存它:

    NSManagedObjectContext *managedObjectContext = [[FTAppDelegate sharedAppDelegate] managedObjectContext];

    _category = (Category *)[NSEntityDescription
                             insertNewObjectForEntityForName:@"Category"
                             inManagedObjectContext:managedObjectContext];

    NSError *error = nil;
    [managedObjectContext save:&error];
    if (error) {
        NSLog(@"error saving: %@",error);
    }

然后编辑类别对象的名称并再次保存。

    _category.name = _nameTextField.text;

    NSManagedObjectContext *managedObjectContext = [[FTAppDelegate sharedAppDelegate] managedObjectContext];

    NSError *error = nil;
    [managedObjectContext save:&error];
    if (error) {
        NSLog(@"error saving: %@",error);
    }

并得到这个错误:

 2013-01-12 17:53:11.862 instacat[7000:907] Unresolved error Error Domain=NSCocoaErrorDomain Code=134030 "The operation couldn’t be completed. (Cocoa error 134030.)" UserInfo=0x2027b300 {NSAffectedObjectsErrorKey=(
"<Category: 0x1ed43cf0> (entity: Category; id: 0x1ed52970 <x-coredata://68E5D7B6-D461-4962-BC07-855349DB3263-7000-00000141BAB4C399/Category/tE8AB2F2E-C14C-4E93-8343-CC245B7726622> ; data: {\n    categoryId = nil;\n    isPrivate = 0;\n    name = techies;\n    users =     (\n    );\n})"
), NSUnderlyingException=Cannot update object that was never inserted.}, {
    NSAffectedObjectsErrorKey =     (
         "<Category: 0x1ed43cf0> (entity: Category; id: 0x1ed52970 <x-coredata://68E5D7B6-D461-4962-BC07-855349DB3263-7000-00000141BAB4C399/Category/tE8AB2F2E-C14C-4E93-8343-CC245B7726622> ; data: {\n    categoryId = nil;\n    isPrivate = 0;\n    name = techies;\n    users =     (\n    );\n})"
    );
     NSUnderlyingException = "Cannot update object that was never inserted.";
}

感谢您的时间和考虑。

我正在使用 AFIncrementalStore。

Answer 1

这样的事情怎么样:

self.category.name = self.nameTextField.text;

NSManagedObjectContext *managedObjectContext = [[FTAppDelegate sharedAppDelegate] managedObjectContext];

if(![self.category isInserted])
{
    [managedObjectContext insertObject:self.category];
}

NSError *error = nil;
[managedObjectContext save:&error];
if (error) {
    NSLog(@"error saving: %@",error);
}

基本上检查对象是否已经被插入，如果没有，插入它然后保存上下文。