[Draft]iOS.Architecture.16.Truth-information-flow-and-clear-responsibilities-immutability

Posted 2020-11-03 XiaoKL

Concept: Truth, Information Flow, Clear Responsibilities and Immutability

 

1. Truth

 

1.1 Single Source of Truth

单一的事实/真想来源

Ref[2] Ref[3]

 

"One core principle that is good to keep in mind when modelling various states is to try to stick to

a “single source of truth” as much as possible. One easy wayto look at this is that you should never

need to check for multiple conditions to determine what state you are in." Ref[2]

 

1.2 Truth vs 

Ref[1] 

 

2. Information Flow (Data Flow)

 

 

 

3. Clear Responsibilities

 

 

4. Immutability

google "immutable object in objective-c"

 

4.0 Mutable vs Immutable Object 

 

 

4.1 Why immutable object?

 

Value Object

“In computer science, a value object is a small object that represents a simple entity

whose equality is not based on identity: i.e. two value objects are equal when they

have the same value, not necessarily being the same object.

 

Value objects should be immutable: this is required for the implicit contract that

two value objects created equal, should remain equal. It is also useful for value objects

to be immutable, as client code cannot put the value object in an invalid state or

introduce buggy behaviour after instantiation.” Ref[9]

 

Value Object and Mantle

"For an Objective-C class to be used as a value object, it needs to be immutable,

support value equality, implement proper hashing, and support NSCopying.

Mantle provides the latter three just by subclassing MTLModel. "

 

4.2 Immutability and Builder Pattern

Ref[4] Ref[5] Ref[8]

Too many parameters in initializer method

 

4.3 Builder Pattern in Objective-C and Swift

Objective-C Version

http://www.cnblogs.com/cwgk/p/9013260.html 

Swift Version

Todo

 

4.4 Code Generation (DSL, ruby)

Ref[10] 

 

4.5 Code Generation (remodel) 

Ref[11] Ref[12] 

 

Remodel Plugin

https://github.com/facebook/remodel/blob/master/PLUGINS.md 

4.6 Code Generation (plank)

Ref[13]

 

4.7 Consistency

Ref[14]

 

 

---

Reference

1. Advanced ios Application Architecture and Patterns

http://asciiwwdc.com/2014/sessions/229

2. Modelling state in Swift

https://medium.com/@johnsundell/modelling-state-in-swift-3751a4acb8f3

Rules: 

A single source of truth

Making states exclusive

Rendering reactively

Handling state changes

Extracting information

 

3. Single source of truth

https://en.wikipedia.org/wiki/Single_source_of_truth

4. Immutability and Builder Pattern

http://kean.github.io/post/immutability-and-builder-pattern

• objc.io: Value Objects
• Wikipedia: Builder Pattern
• Wikipedia: Immutable Objects
• Concepts in Objective-C Programming: Object Mutability

5. Value Objects (Read Again)

https://www.objc.io/issues/7-foundation/value-objects/

6. Mutability, aliasing, and the caches you didn\'t know you had

https://garbagecollective.quora.com/Mutability-aliasing-and-the-caches-you-didnt-know-you-had 

7. Boundaries (To Read)

A talk by Gary Bernhardt from SCNA 2012

https://www.destroyallsoftware.com/talks/boundaries

8. Improving Immutable Object Initialization in Objective-C

http://holko.pl/2015/05/12/immutable-object-initialization/

AHKBuilder

9. Simplifying Objective-C Value Objects with Mantle and the Builder Pattern (AAAA+)

https://spin.atomicobject.com/2015/11/02/objective-c-value-objects-mantle/

10. Objective-C Value Objects: Code Generation

https://spin.atomicobject.com/2015/12/16/objective-c-value-objects-code-generation/

11. Building and managing iOS model objects with Remodel

https://code.facebook.com/posts/1154141864616569/building-and-managing-ios-model-objects-with-remodel/

12. remodel

https://github.com/facebook/remodel

Remodel is a tool that helps iOS and OS X developers avoid repetitive code by generating Objective-C

models that support coding, value comparison, and immutability.

13. plank

A tool for generating immutable model objects https://pinterest.github.io/plank/

https://github.com/pinterest/plank/

14. ConsistencyManager-iOS

https://github.com/plivesey/ConsistencyManager-iOS

A library that manages consistency of immutable models https://plivesey.github.io/Consistenc…

15. iOS响应式架构

http://blog.mrriddler.com/2017/06/28/iOS响应式架构/

16. Single Source of Truth Principal in Software Development (android) 

https://www.youtube.com/watch?v=Ex9IT1bq0PQ

https://codingwithmitch.com/courses/android-local-database-cache-rest-api/demo/

In this course you\'ll learn how to build a local database cache with SQLite and Room.

The cache retrieves data from a REST API using Retrofit2. Architecture is MVVM.

17. Difference between Single Source Of Truth and Single Responsibility Principle?

https://softwareengineering.stackexchange.com/questions/284874/difference-between-single-source-of-truth-and-single-responsibility-principle

18. Understanding One Source of Truth for Analytics

https://blogs.workday.com/understanding-one-source-truth-analytics/

19. The Single Source of Truth

https://blog.buckets.co/the-single-source-of-truth-430b61d10e19

20. Why Single Source of Truth Data Systems Kill Team Collaboration

https://unito.io/blog/a-single-source-of-truth-data-system-kills-team-collaboration-heres-why/

21. Single Source of Truth

https://www.dragon1.com/concepts/single-source-of-truth

22. Single Source of Truth…and Why it Matters

https://medium.com/@elisavaccaro/single-source-of-truth-and-why-it-matters-a68e28b8c175

23. 应用架构指南

https://developer.android.com/jetpack/docs/guide