Method and apparatus of route guidance

An apparatus comprising:

• a memory capable of caching a plurality of map partition data;
• a processor in communication with the memory so as to process the plurality of map partition data in accordance with instructions;
• and
• a display in communication with, and displaying information received from, the processor;
• the instructions comprising:
• prefetching a first plurality of map partition data for a first area from a remote computer at a first point in time, each of the first plurality of map partition data being encoded with information for generating driving directions;
• determining, at a second point in time later than the first point in time, whether the remote computer is accessible;
• if the remote computer is accessible, fetching a second plurality of map partition data for a second area from the remote computer at the second point, the second plurality of map partition data being encoded with information for generating driving directions, the second area being within a predetermined distance from a current location of the apparatus and partially intersecting the first area;
• storing the first plurality of map partition data and the second plurality of map partition data in a memory;
• determining, at a third point in time later than the second point in time, whether the remote computer is accessible;
• if it is determined that the remote computer is not accessible, retrieving map data of the first plurality of map partition data and the second plurality of map partition data from the memory;
• assembling the map data representing a geographic region;
• and
• generating a route to a destination using the map data.

A non-transitory computer readable medium storing instructions executable by a computing device to perform a method of generating a route to a destination, the method comprising:

• prefetching a first plurality of map partition data for a first area from a remote computer at a first point in time, each of the first plurality of map partition data being encoded with information for generating driving directions;
• determining, at a second point in time later than the first point in time, whether the remote computer is accessible;
• if the remote computer is accessible, fetching a second plurality of map partition data for a second area from the remote computer at the second point in time, the second plurality of map partition data being encoded with information for generating driving directions, the second area being within a predetermined distance from a current location of the user device and partially intersecting the first area;
• storing the first plurality of map partition data and the second plurality of map partition data in a memory;
• determining, and a third point in time later than the second point in time, whether the remote computer is accessible;
• if it is determined that the remote computer is not accessible, retrieving map data of the first plurality of map partition data and the second plurality of map partition data from the memory;
• assembling the map data representing a geographic region;
• and
• generating a route to a destination using the map data.