Combine! All the things

Transcript

1. Combine! All the things
   Ritesh Gupta
   @_riteshhh
   

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2. Ritesh Gupta
   @_riteshhh
   riteshhh.com
   github.com/riteshhgupta
   

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4. Beta 1, 2, 3, 4…!
   

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5. Combine
   • It provides a declarative Swift API for processing
   values over time
   • These values can represent many kinds of
   asynchronous events
   • Customise handling of asynchronous events by
   combining event-processing operators
   

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6. • It’s a reactive framework by Apple
   Combine
   

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7. Reactive (Rx) Programming
   

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8. Rx Programming
   • Observer Pattern (publish >> observe)
   • Operations (dependent tasks)
   • Simple (yet powerful) Operators like merge, zip, debounce…
   • Open Source: ReactiveSwift, RxSwift
   

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9. Why we need Rx?
   

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10. Why Rx?
    • multiple async tasks
    • better state management
    • loose coupling of components
    • declarative & cleaner api
    

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11. source: https://twitter.com/diegopetrucci/status/1135655480825655297
    Current state of Combine
    

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12. Foundation of Combine!
    

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13. Foundation of Combine!
    • Publisher
    • Subscriber
    • Operators (map, flatMap, filter, merge, zip…)
    

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14. Publisher
    

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15. Publisher
    • emit sequence of values over time
    • delivers values to one or more Subscriber instances
    • protocol with two generic types (Output, Error)
    • completion via .finished or .failure
    

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16. Publisher
    

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17. • Notification Publisher
    • URLSession Publisher
    • Just, Future
    • CurrentValueSubject, PassthroughSubject
    Free Publishers
    

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18. Subscriber
    

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19. Subscriber
    • receive emitted values from a Publisher
    • represents end of the chain of a stream
    • protocol with two generic types (Input, Error)
    • can cancel a subscription
    • Sink, Assign, AnySubscriber
    

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20. Subscriber
    

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21. Publisher
    Subscriber
    

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22. Subscription
    

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23. Assign
    

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24. Assign
    

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25. Sink
    

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26. Sink
    

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27. subscribe(on:)
    vs
    receive(on:)
    

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28. Threading
    

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29. • `receive(on:)` affects downstream events
    • `subscribe(on:)` affects upstream events
    • In the example, requests to `$queryPublisher` are
    performed on `backgroundQueue`, but elements
    received from it are performed on `Dispatch.main`
    Threading
    

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30. Lifecycle of Publisher &
    Subscriber
    

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31. Lifecycle
    

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32. Operators
    

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33. • pre-defined functions (publishers)
    • used b/w a publisher & a subscriber
    • transform the stream
    • map, flatMap, filter, merge, zip, debounce…
    Operators
    

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34. Operators
    

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35. Map
    

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36. Filter
    

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37. Debounce
    

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38. FlatMap
    

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39. Merge
    

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40. Zip
    

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41. Demo
    

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42. Next?
    

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43. • Subject
    • Memory Management
    • Error Handling
    • Debugging
    Next?
    

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44. • ConnectablePublisher
    • Back Pressure (`Demand`)
    • Multicasts
    Next?
    

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45. Further Reading
    

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46. Thank you!
    

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