How do I apply Promise in iOS

1. Future/Promise on iOS
Thinh VoXuan
Summer 2016

2. 1. Callback hell & Another problem
2. What is promise ?
3. Chaining tasks pattern
4. Parallel tasks pattern
5. Errors handler
6. Example with Bolt Framework
7. Advantages
Agenda
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3. • Synchronous vs Asynchronous
Not Today
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4. Callback hell & Another problems
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5. Callback hell & Another problems
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6. Callback hell & Another problems
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7. Callback hell & Another problems
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How could I call 3 requests on same times?

8. Callback hell & Another problems
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Hard to understand
and follow the logic ?
What happen when
1 request has error?

9. What is promise ?
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• Deferred State
• pending
• Settled State
• fulfilled
• rejected

10. What is promise ? - fulfilled
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fulfilled could be
•Value
•Object
•Another Promise

11. What is promise ? - rejected
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rejected could be
•Error

12. Chaining tasks pattern
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• continueWith: Enqueues a given closure
to be run once this task is complete.
• continueWithTask: This is the method that
all other continuations must go through.
• continueOnSuccessWith
(continueOnSuccessWithTask): Enqueues
a given closure to be run once this task
completes with success (has intended
result).
• continueOnErrorWith
(continueOnErrorWithTask): Enqueues a
given closure to be run once this task
completes with error.

13. Chaining tasks pattern
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14. Chaining tasks pattern
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15. Chaining tasks pattern
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16. Chaining tasks pattern - continueWith
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17. Chaining tasks pattern
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18. Parallel tasks pattern
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• whenAll : Creates a task that will be completed
after all of the input tasks have completed.
• whenAllResult: Like whenAll. The result of the
task is going an array of results of all tasks in the
same order as they were provided.
• whenAny: Creates a task that will complete when
any of the input tasks have completed.

19. Parallel tasks pattern
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20. Parallel tasks pattern - whenAll
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21. Parallel tasks pattern - whenAllResult
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22. Parallel tasks pattern – whenAny
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23. Could only go with tasks on function
•continueWith
•continueOnErrorWith
If error occurs next task on
continueOnSuccessWith will never run
Errors handler
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24. • How to create Promise from
Asynchronous function
• How to create Promise from Synchronous
function
BoltFramework
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25. BoltFramework – Create Promise
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BoltFramework/Bolt-Swift

26. BoltFramework – Create Promise
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BoltFramework/Bolt-ObjC

27. • Readable code
• Testable code
• Component task
• Re-useable code
Advantages
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28. Chaining tasks pattern - continueOnSuccessWith
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29. References
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• https://github.com/BoltsFramework/Bolts-Swift
• https://github.com/BoltsFramework/Bolts-ObjC
• http://www.slideshare.net/NicholasvandeWalle

30. Q&A
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31. Thank you
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32. • Software Engineer at GEEKUp company:
• iOS
• Web
• Scrum Master
• love sharing & technical excellent
• Website: http://thinhvoxuan.me
• Github: https://github.com/voxuanthinh
• Skype: voxuan.thinh
whoami
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