Lock screen by API in macOS

Question

Is there an API, that can lock the screen as the menu bar entry you can add from Keychain preferences?

This Keychain function is (was) lock

Answer 1

I don't see anything documented as such, but the menu uses the ScreenSaver framework, which defines this:

@interface ScreenSaverDefaults : NSUserDefaults 
{
@private
    NSMutableDictionary     *_defaults;
    NSMutableDictionary     *_registeredDefaults;
    NSString                *_userName;
    NSString                *_domainName;
    BOOL                    _dirty;
    BOOL                    _screenLockPrefChanged;
}

+ (id) defaultsForModuleWithName:(NSString *)inModuleName;

@end