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

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

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

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Add background service

3. Add MagicBallBackgroundService target (choose Cocoa Application).
4. Remove the window from it's MainMenu.xib or Main.storyboard (whichever you have)
5. Add a key-value pair to it's Info.plist: 'Application is background only' : YES
6. 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.

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Embedding Service into Client application

7. 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

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Set the correct mach label of the Service

8. Locate additional_files direcory in the project root firectory.
9. Add IPC.swift to both targets
10. Set the kServiceName constant to the Bundle identifier of the Service

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Configure the Client

11. Go to AppController class and implement:

• start()
• stop()
• connect()
• getDecision()

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Configure the Service

12. Download Magic8BallService.swift and Magic8Ball.swift
13. Add them to the Service target
14. Implement start(), stop(), listener(_ listener: NSXPCListener, shouldAcceptNewConnection newConnection: NSXPCConnection) -> Bool and getDecision(replyBlock: @escaping DecisionReplyBlock)
15. In the AppDelegate class make a property of Magic8BallService instance.
16. Call start() on this instance in applicationDidFinishLaunching().
17. Call stop() on this instance in applicationWillTerminate()

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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.

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Part 2: talking to the Client

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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'.

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18. 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