How do I determine the OS version at runtime in OS X or iOS (without using Gestalt)?

Question

The Gestalt() function located in CarbonCore/OSUtils.h has been deprecated as of OS X 10.8 Mountain Lion.

I often use this function to test the version of the OS X operating system at runtime (see the toy example below).

What other API could be used to check the OS X operating system version at runtime in a Cocoa application?

int main() {
    SInt32 versMaj, versMin, versBugFix;
    Gestalt(gestaltSystemVersionMajor, &versMaj);
    Gestalt(gestaltSystemVersionMinor, &versMin);
    Gestalt(gestaltSystemVersionBugFix, &versBugFix);

    printf("OS X Version: %d.%d.%d\n", versMaj, versMin, versBugFix);
}

Answer 1

On OS X 10.10 (and iOS 8.0), you can use [[NSProcessInfo processInfo] operatingSystemVersion] which returns a NSOperatingSystemVersion struct, defined as

typedef struct {
    NSInteger majorVersion;
    NSInteger minorVersion;
    NSInteger patchVersion;
} NSOperatingSystemVersion;

There is also a method in NSProcessInfo that will do the comparison for you:

- (BOOL)isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion)version

Beware, although documented to be available in OS X 10.10 and later, both operatingSystemVersion and isOperatingSystemAtLeastVersion: exist on OS X 10.9 (probably 10.9.2) and work as expected. It means that you must not test if NSProcessInfo responds to these selectors to check if you are running on OS X 10.9 or 10.10.

On iOS, these methods are effectively only available since iOS 8.0.