ARC下的这段代码有什么问题？我得到以上错误：
- (Moment *)initMoment:(BOOL)insert {
if (insert) {
self.moment = [NSEntityDescription insertNewObjectForEntityForName:@"Moment" inManagedObjectContext:self.managedObjectContext];
} else {
self.moment = [NSEntityDescription insertNewObjectForEntityForName:@"Moment" inManagedObjectContext:nil];
}
return self.moment;
}
