/ipc_workshop

Starter project for my workshop 'Interprocess Communication: from Zero to Hero in 2 Hours'

Primary LanguageSwift

Workshop starter project

'IPC: from Zero to Hero in 2 Hours' 🎱

It is a workshop for iOS developers, macOS developers, that have never used Objective-C XPC interface for inter-process communication.

Attendees developed a 'Magic 8 Ball' application: similar to a popular fortune-telling toy 🎱

The starter project contains a UI application with a window similar to a ball. Try to double-click it, and it will shake.

The goal is to develop a background process and setup communication with it.

Part 1: talking to the Service

For this part, omit instructions, surrounded with
/// --- PART 2 ---

  1. Download starter project.
  2. Launch it, see, what it has.

Add background service

  1. Add MagicBallBackgroundService target (choose Cocoa Application).
  2. Remove the window from it's MainMenu.xib or Main.storyboard (whichever you have)
  3. Add a key-value pair to it's Info.plist: 'Application is background only' : YES
  4. Go to MagicBallBackgroundService target's capabilities and switch App Sandbox off.

Sidenote 1: XPC works with Sandbox enabled, just another setup is required.

Sidenote 2: We should set 'Application is background only' because we don't want any Dock icon or Main menu in the Menu bar.

Embedding Service into Client application

  1. Go to Client app's Build Phases and
  • add MagicBallBackgroundService to Dependencies list
  • add a new Copy Files phase with Destination: Wrapper; set Subpath : Contents/Library/LoginItems. Press + and add MagicBallBackgroundService.app

Set the correct mach label of the Service

  1. Locate additional_files direcory in the project root firectory.
  2. Add IPC.swift to both targets
  3. Set the kServiceName constant to the Bundle identifier of the Service

Configure the Client

  1. Go to AppController class and implement:
  • start()
  • stop()
  • connect()
  • getDecision()

Configure the Service

  1. Download Magic8BallService.swift and Magic8Ball.swift
  2. Add them to the Service target
  3. Implement start(), stop(), listener(_ listener: NSXPCListener, shouldAcceptNewConnection newConnection: NSXPCConnection) -> Bool and getDecision(replyBlock: @escaping DecisionReplyBlock)
  4. In the AppDelegate class make a property of Magic8BallService instance.
  5. Call start() on this instance in applicationDidFinishLaunching().
  6. Call stop() on this instance in applicationWillTerminate()

Run the project!

Run the Client target. Think of a Yes-No question and double-click the ball to see if you get the answer.

Part 2: talking to the Client

Let's say, that background service wants to send the user 'Signs' about their future. To do that it needs to be able to call the Client application and pass it the 'Sign'.

  1. Go through the project and follow the instructions, surrounded by /// --- PART 2 ---

Notes:

  • open Activity Monitor application and search for 'magic' to see, if both apps are running
  • in order to terminate the background service you should manually quit the main application
  • the background service is not automatically attached to Xcode. You can attach to it manually or add some NSLog() logs and see them in the Console application