Acquisition of version number in iOS and its significance

 corresponds to the version number of the release, that is, build#define app_version     /// corresponds to the version number that was recorded in development #define App_version_old     [[[NSBundle Mainbundle] infodictionary] Objectforkey: (NSString *) Kcfbundleversionkey]

Generally on the version of the three-level A.B.C

A represents a substantially modified version, such as a revision that implements a new feature or a major change.

b represents the revision to achieve a more prominent feature.

C Stands for maintenance version

Acquisition of version number in iOS and its significance