Question summary:
Consider a class SyncObject that is KVC-compliant with properties such as: time, someValue,
As a further clarification, I'd like to point out that in mja's answer the key thing is
[syncEntityMapping mapKeyPath:@"mySyncArray" toRelationship:@"mySyncArray" withMapping:mngObjMapping];
This says "the mySyncArray keypath is an array which contains objects that should be mapped according to mngObjMapping".