RxSwift for Beginners - how to avoid a headache of reactive programming
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RxSwift for Beginners - how to avoid a headache of reactive programming
- 1. RXSWIFT đť HOW TO AVOID THE HEADACHE AND FOCUS ON THE MOST IMPORTANT ELEMENTS OF IT.
- 3. WHAT THE HECK ISREACTIVE PROGRAMMING?
- 4. REACTIVEX.IO âAN API FOR ASYNCHRONOUS PROGRAMMING WITH OBSERVABLESTREAMSâ
- 5. THE OBSERVER PATTERN DONE RIGHT REACTIVEX IS A COMBINATION OF THE BEST IDEAS FROM THE OBSERVER PATTERN, THE ITERATOR PATTERN, AND FUNCTIONAL PROGRAMMING
- 6. WHY YOU WOULD WANT TO HAVE RXSWIFTINTHEPROJECT?
- 7. - it clears up and streamlines the async calls in your app, especially those that might happen in diďŹerent timeframes đ - helps with error handling during async operations - all thrown errors are passed to the subscription block, no more ifâs! đ - helps with operations clarity with clear inline notation - less line of code đ - helps with dividing your code to smallest possible blocks â - allows us to forget about delegates by using Subjects đ - gives us plenty of easy-to-use operators to achieve your task đ WHYYOUSHOULDCARE
- 8. BUTALSOâŚ
- 9. ⢠It will be easier for you to switch to Combine whenever Apple will update their framework with everything RxSwift has to oďŹer (iOS 15-ish I hope đ) ⢠Rx is a standard across all major platforms (we have RxKotlin, RxJava, RxJs, etc.) - if you learn it once, you will probably not come back and you can read code on other plaforms easily đ BUTALSOâŚ
- 11. ⢠RxSwift is hard to get used to in the beginning since you need to rewire your brain a bit đ§ ⢠You WILL make mistakes in the beginning, but as always, refactor is your friend, and with smaller blocks it is easier to fix things â ⢠... this presentation will not make you a master Jedi. đ BUTATTHESAMETIMEâŚ
- 15. NEEDANEXAMPLE?
- 16. LET'S THINK ABOUT A SIMPLE EXAMPLE IN OUR APP. WHYWEDOEVENNEEDRXSWIFT? We have a list with a Search Bar. Whenever user is typing something to the search bar, he gets results. Those results are mapped to ViewModels. Then they are passed to the TableView and the View is refreshed. SOUNDSFAMILIAR?
- 17. LET'S THINK ABOUT A SIMPLE EXAMPLE IN OUR APP. WHYWEDOEVENNEEDRXSWIFT?
- 18. LET'S THINK ABOUT A SIMPLE EXAMPLE IN OUR APP. WHYWEDOEVENNEEDRXSWIFT? But if we want to modify the app so we want to: ⢠reduce number of unnecessary text inputs & API calls đą ⢠retry the call if it fails đ ⢠map response to a model that is readable by our app 𧰠⢠catch any errors that might occur đ ⢠keep our memory clear when we leave the screen đ
- 19. LET'S THINK ABOUT A SIMPLE EXAMPLE IN OUR APP. WHYWEDOEVENNEEDRXSWIFT? TEXTFIELD DELEGATES SESSION RETRY MEMORY MANAGEMENT DEBOUNCING
- 20. LET'S THINK ABOUT A SIMPLE EXAMPLE IN OUR APP. WHYWEDOEVENNEEDRXSWIFT?
- 25. NOTHING HAPPENS UNTIL YOU .SUBSCRIBE
- 26. SUBJECTS
- 27. SUBJECTS ARE DEFINING YOUR STREAM, THEY ARE YOUR STARTING POINT. SUBJECTS They are a really nice way of getting rid of any delegates. There are four main subjects in RxSwift world, but you will mainly use two of them in your projects. PUBLISHSUBJECT BEHAVIORRELAY
- 28. SUBJECTS ARE DEFINING YOUR STREAM, THEY ARE YOUR STARTING POINT. SUBJECTS PUBLISHSUBJECT â˘If you need to only emitnewelements to subscribers â˘Starts empty â˘Mostly used to notify about some changes in the app (i.e. user gets a new message)
- 29. SUBJECTS ARE DEFINING YOUR STREAM, THEY ARE YOUR STARTING POINT. SUBJECTS PUBLISHSUBJECT â˘Starts withinitialvalue â˘Preserves the value â˘Emits the value to subscribers whenever it changes â˘Mostly used to keep some values in memory BEHAVIORRELAY
- 30. HOW TO DEFINE AND USE A SUBJECT? SUBJECTS
- 31. TRAITS
- 32. THEY DEFINE TYPE OF OPERATIONS YOU WANT TO OBSERVE AND SUBSCRIBE TO. TRAITS OBSERVABLE SINGLE COMPLETABLE
- 33. OBSERVABLE When you need to observe the change everytimesomethinghappens (i.e. user taps a button or a number is selected)
- 34. SINGLE When you only want to get a singlevalue out of the stream and then dispose it at the end (i.e. getting resource from API).
- 35. COMPLETABLE When you need to perform an operation but it doesnotreturnanythingand youjustwaitforittocomplete (i.e. uploading something, saving something to DB)
- 36. BY USING OPERATORS LIKE .FLATMAP, YOU CAN CONVERT YOUR DATA AND USE DIFFERENT TRAITS.
- 37. OPERATORS
- 38. THERE ARE PLENTY OF THEM OPERATORS
- 44. HOW TO DEBUG RXSWIFT
- 45. ⢠Well, you are kind of doomed đŁ. ⢠You can use .debug() somewhere down the stream and use a mix of breakpoints and prints (unfortunately) ⣠in your project. HOWTODEBUGRXSWIFT
- 47. ⢠You don't need to know and use all of operators and traits from RxSwift. Some of the Rx operators are not even available in Swift. â ⢠Do not use RxSwift for everything. Start with simple elements - basic async/API calls, then go to more advanced examples like combining multiple observables and then adding some side-eďŹects like loaders, error catching, etc. đ¤ RXSWIFTBESTPRACTICES
- 48. ⢠Do not expose a Subject outside of your service layer class (use Observable), so nobody outside of the class can modify or publish to the stream directly. Exposing subject as an Observable makes it a one-way street. 𦺠⢠Use [unowned/weak self] in every closure that uses self to avoid memory leaks âź This is the ultimate enemy of RxSwift đť ⢠If you don't want to stop your subscription after an error, use .materialize đŞ. It will change wrap your events into Result-like structures that you can handle in your subscription block. ⢠If your RxSwift code does not compile, write simpler code đľ. Check your types. Swift compiler does not have a good RxSwift understanding 𤏠RXSWIFTBESTPRACTICES
- 51. QUESTIONS?