Objective C basics

macOS code. Code I am writing to get started with Objective-C and macOS. So far, wrote code on

1. NSSTring, NSARray,NSDictionary,etc.,
2. NSTasks,
3. launchd,
4. A sample custom delegate,
5. NSRunLoop and NSTimer,
6. Manipulating dynamic store with SCDynamicStore,
7. Get notifications on state change in dynamic store,
8. NSWorkspace: launch app,file, get shutdown,sleep notifications etc,
9. Download URL by three ways (SessionData,SessionDownloadTask,NSData with URL),