Moving from Obj-C to

@attheodo

http://attheo.do

Main Perspectives

  • Engineering

    • Developers who don't feel ready to migrate

  • Engineering Management

    • Managers who see many risks in migrating

Where are we with Obj-C?

  • Not exactly what we want...
  • ...but keeps doing the job for years and years

Where are we with Obj-C?

  • Developed in the early 1980s
  • A strict superset of C in order to allow OOP
    • Deep roots in C
    • Modernisation too difficult
    • Complex build system
  • Apple adopts it as an ecosystem language in 1996
    • APIs, frameworks and design patterns have been battle tested for decades
  • Not going away at least for another 10 years...

So, why Swift?

  • Exactly what you need!
  • ...but some maintenance may prove costly

So, why Swift?

  • Released in 2014 by Apple for the Apple ecosystem (but not only)
    • Open source
    • Swift in the server
  • Only one guy has > 4 years experience
    • No, we can't hire him
    • Chris Lattner = LLVM ❤️
  • Modern, fast, safe
    • Patterns and best-practices still being molded
    • Breaking changes
      • Everyone said "wait for Swift 3.0". Well, we're there.

What are the differences?

  • 5 Pillars
    • New features
      • Value types on steroids
      • Multi-paradigm
    • Tooling
    • Safer
      • Language features prevent errors & crashes
    • Velocity
      • Less files, less code, faster compile times
    • Cleaner syntax
      • The faster your understand, the faster you write
  • 💥 C/C++ interop is a little clunky

What are the differences?

New features

"Everything we can do with reference types we can now do with enums, structs and tuples (value types)"

  • Mutable data structures are risky in multithreaded environments
    • In fact Swift stdlib uses 95 value types and 4 reference types
  • Enums are now building blocks
  • Tuples can lead to more verbose APIs without making them complex (i.e arity, return types)

None of this can co-exist with ObjC though. Only in newly developed  features.

What are the differences?

New features

"Swift is the first protocol-oriented language"

Composition VS Inheritance 👌

What are the differences?

New features

"Functions are first-class citizens"

Functional Programming

⚡️⚡️⚡️

PLUS

What are the differences?

Tooling

  • Header files 👀
  • C infrastructure has complex building phases:
    • Committed dependencies     🙈
    • git submodules                       😷
    • CocoaPods/Carthage             💊
    • Swift Package Manager         🦄

🙈🙈🙈

What are the differences?

Velocity Time

  • Less files in VCS
    • Less code to write
    • Less code to commit 
    • Less code to review
    • Less code to maintain 
    • Faster compile times 

⏰

💰

What are the differences?

Velocity Time

“On the old version, that was a project that took more than a month, with multiple engineers. And with Swift, that was a project that took a week for one engineer.”

https://goo.gl/akMIjy

Well, ok obviously. They had a clearer set of requirements at that point.

What are the differences?

Cleaner syntax

return [
[
  [
    [self.title lowercaseString] stringByReplacingOccurrencesOfString:@"visit" withString:@""] 
    capitalizedString
  ]                     
  stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]
];
return str.lowercased()
       .replacingOccurrences(of: "visit", with: "")
       .capitalized
       .trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)

SWIFT EVERYWHERE!

NOT EVERYTHING IS ENGINEERING. Let's take a step back.

WHY DO WE WANT SWIFT?

  • Why write more clean and predictable code?
    • ✅ Because we want to ship less bugs
  • Why use latest practices?
    • ✅ Because we want to attract the best future colleagues
    • ✅ Because we want to take part in shaping them 🚀
  • Why make development more enjoyable and faster?
    • Product wants faster releases...
    • Engineering wants an enjoyable environment...
    • Let's converge 👩‍❤️‍👩

WHY DO WE WANT SWIFT?

WE ALL WANT TO SHIP A GREAT PRODUCT.

Management Reasons for switching

  • TODAY:
    • Hiring good ObjC developers is getting tougher
      • Proof:

NOT HIRED

Management Reasons for switching

  • TOMORROW
    • Junior people are unlikely they'll start with ObjC
    • Swift is the cool kid in the block, people are enthusiastic about it.

Swift

ObjC

Management Reasons for switching

  • ACME Ltd can attract brand exposure by taking part in the shaping of the ecosystem

💪

Management Reasons for switching

  • Other management teams have already decided

Management Risks

An organisation's most feared word:

CHANGE

  • Migrating to Swift is a strategic change
    • All BUs need to be aware & aligned with this strategy
    • Engineering still needs to keep aligned with the overall strategy though...
    • Easier said than done
  • Change always starts with lots of friction
    • ​Needs cross-functional planning & coordination

Management Risks

  • Difficult to justify ROI at early stages
    • Most things will be transparent to end users at first...
    • Development might feel slower at first...

 

  • However down the road:
    • Development will have more velocity and stability
      • More, and more stable, features
        • Happy users! 
      • Relevant teams (QA, support) will get relieved
    • Healthier and less stressful synergy between Product and Engineering

SWOT Analysis

STRENGTHS

  • Better long term support
  • Healthier Engineering, QA, Support sunergy
  • Faster & more stable releases
  • Bleeding edge tech stack
  • Great side-by-side interop with ObjC (set our own pace)

WEAKNESSES

  • Possible slowdown in early weeks (coordination costs)
  • Real benefits of the language will shine at full migration
  • Probability to spent a few days migrating when v4.0 comes out
  • Throw out some of our current code

SWOT Analysis

OPPORTUNITIES

  • Attract better developers now and in the future
  • Expose brand by more actively taking part in the ecosystem
  • Embrace the change with a new, clean, testable & scalable architecture
  • Pay off accumulated technical debt

THREATS

  • Cosmic event that causes Apple to really mess Swift/ObjC interop
  • Swift ABI roadmap is a lie
  • It just not works™

Suggested Roadmap

  • 👣 Discuss new architecture (1 day)
  • 🏃 Finish web/iOS parity in ObjC
  • ✍️ Create a styleguide, document API (~2-3 days)
  • 💀 Clean up zombie-code (1-2 days)
  • ✌️ Rewrite data layer in Swift (~1-2 weeks)
    • ​The foundation of views & business logic
    • Flexible architecture  + tests
  • 🚧 Adjust presentation layer to use the new architecture (1 week)​
  • 💪 Every new file gets written in Swift
  • 👀 When there's slack time, rewrite existing VCs in Swift

Suggested Roadmap

Bottom line it will take a total of 1 month to truly start harvesting what we seow.

After all, it's still good ol' Cocoa framework we're dealing with.

Thank you

Discussion

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