I have a requirement in which locally created events have to be synced with sever synchroniously. To explain this briefly lets consider this scenario, there were two events occurred in the offline app called A and B here A > B. In this case B should sync only when A is completed its sync.
To fix this I must have an extra attribute in my entity to identify which is created earlier. This attribute can maintain either created time or any incremental number.
Here only i am facing some clarifications
Solution :1 Based on created time
If I maintain created time in that attribute, Will it be proper for below scenario
Lets say I created on event “A” today then I changed my device’s date to previous day’s date and then I am coming back to my app and creating an another event “B”. Here which one will be earlier? if app says “B” is most recently inserted object then there is no issue I can stick with this solution itself otherwise I need to move to some other solution. Is there any optimised solution to find inserted order by maintaining created time?
Solution :2 Based on incremental number
I believe core data does not provide any auto-incremental id so we need to maintain it manually. If so what would be the better approach to maintain the maximum assigned value? Will it be good if I store the maximum assigned value in NSUserDefaults? Whenever app creates an event the value will be fetched from NSUserDefaults and +1 will be added and then I will assign final value to the event. Is this approach proper one? or else please guide me if you know any better solution
There is no auto-incrementing number built into Core Data as that is more a business logic specific item. However, it is not difficult to implement.
You can store the last number used in the metadata of the persistent store. During your insert, simply increment that number, add it to each entity as you go. When you are done inserting, update the number in the metadata.
That is how Core Data updates its own insert numbers for the objectID.