The marketing release number is for the customers, called version number. It starts with 1.0 and goes up for major updates to 2.0, 3.0, for minor updates to 1.1, 1.2 and for bug fixes to 1.0.1, 1.0.2 . This number is oriented about releases and new features.
The build number is mostly the internal number of builds that have been made until then. But some use other numbers like the branch number of the repository. This number should be unique to distinguish the different nearly the same builds.
As you can see, the build number is not necessary and it is up to you which build number you want to use. So if you update your Xcode to a major version, the build field is empty. The version field may not be empty!.
To get the build number as a NSString variable:
NSString * appBuildString = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"];
To get the version number as a NSString variable:
NSString * appVersionString = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"];
If you want both in one NSString:
NSString * versionBuildString = [NSString stringWithFormat:@"Version: %@ (%@)", appVersionString, appBuildString];
This is tested with Xcode Version 4.6.3 (4H1503). The build number is often written in parenthesis / braces. The build number is in hexadecimal or decimal.
In Xcode you can auto-increment the build number as a decimal number by placing the following in the Run script build phase in the project settings
#!/bin/bash
buildNumber=$(/usr/libexec/PlistBuddy -c "Print CFBundleVersion" "$INFOPLIST_FILE")
buildNumber=$(($buildNumber + 1))
/usr/libexec/PlistBuddy -c "Set :CFBundleVersion $buildNumber" "$INFOPLIST_FILE"
For hexadecimal build number use this script
buildNumber=$(/usr/libexec/PlistBuddy -c "Print CFBundleVersion" "$INFOPLIST_FILE")
buildNumber=$((0x$buildNumber))
buildNumber=$(($buildNumber + 1))
buildNumber=$(printf "%X" $buildNumber)
/usr/libexec/PlistBuddy -c "Set :CFBundleVersion $buildNumber" "$INFOPLIST_FILE"
