Arc vs Objective-C: What are the differences?
Arc: A dialect of the Lisp programming language developed by Paul Graham and Robert Morris. Arc is designed for exploratory programming: the kind where you decide what to write by writing it. A good medium for exploratory programming is one that makes programs brief and malleable, so that's what we've aimed for. This is a medium for sketching software; Objective-C: The primary programming language you use when writing software for OS X and iOS. Objective-C is a superset of the C programming language and provides object-oriented capabilities and a dynamic runtime. Objective-C inherits the syntax, primitive types, and flow control statements of C and adds syntax for defining classes and methods. It also adds language-level support for object graph management and object literals while providing dynamic typing and binding, deferring many responsibilities until runtime.
Arc and Objective-C can be primarily classified as "Languages" tools.
Uber Technologies, Instagram, and Pinterest are some of the popular companies that use Objective-C, whereas Arc is used by Helpful, Cask, and Icalia Labs. Objective-C has a broader approval, being mentioned in 851 company stacks & 363 developers stacks; compared to Arc, which is listed in 7 company stacks and 6 developer stacks.
What is Arc?
What is Objective-C?
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By mid-2015, around the time of the Series E, the Digital department at WeWork had grown to more than 40 people to support the company’s growing product needs.
By then, they’d migrated the main website off of WordPress to Ruby on Rails, and a combination React, Angular, and jQuery, though there were efforts to move entirely to React for the front-end.
The backend was structured around a microservices architecture built partially in Node.js, along with a combination of Ruby, Python, Bash, and Go. Swift/Objective-C and Java powered the mobile apps.
These technologies power the listings on the website, as well as various internal tools, like community manager dashboards as well as RFID hardware for access management.
At the heart of Uber’s mobile app development are four primary apps: Android rider, Android driver, iOS rider, and iOS driver. Android developers build in Java, iOS in Objective C and Swift. Engineers across both platforms land code into a monolithic code base that ships each week.
They use some third-party libraries, but often build their own, since “Many open source libraries available are general-purpose, which can create binary bloat. For mobile engineering, every kilobyte matters.”
On Android, the build system is Gradle. For the UI, Butter Knife binds views and callbacks to fields and methods via annotation processing, and Picasso provides image loading.
As for iOS, all of the code lives in a monorepo built with Buck. For crash detection, KSCrash reports crashes to the internal reporting framework.
Excerpts from how we developed (and subsequently open sourced) Uber's cross-platform mobile architecture framework, RIBs , going from Objective-C to Swift in the process for iOS: https://github.com/uber/RIBs
Uber’s new application architecture (RIBs) extensively uses protocols to keep its various components decoupled and testable. We used this architecture for the first time in our new rider application and moved our primary language from Objective-C to Swift. Since Swift is a very static language, unit testing became problematic. Dynamic languages have good frameworks to build test mocks, stubs, or stand-ins by dynamically creating or modifying existing concrete classes.
Needless to say, we were not very excited about the additional complexity of manually writing and maintaining mock implementations for each of our thousands of protocols.
The information required to generate mock classes already exists in the Swift protocol. For Uber’s use case, we set out to create tooling that would let engineers automatically generate test mocks for any protocol they wanted by simply annotating them.
The iOS codebase for our rider application alone incorporates around 1,500 of these generated mocks. Without our code generation tool, all of these would have to be written and maintained by hand, which would have made testing much more time-intensive. Auto-generated mocks have contributed a lot to the unit test coverage that we have today.
We built these code generation tools ourselves for a number of reasons, including that there weren’t many open source tools available at the time we started our effort. Today, there are some great open source tools to generate resource accessors, like SwiftGen. And Sourcery can help you with generic code generation needs:
(GitHub : https://github.com/uber/RIBs )
Basically, the trajectory was we had our iOS app, which started out native, right? It started as a native app, and then we realized you have to go through a review process and it’s slow, and at a very early stage, it made sense for us to make it a wrapped web view. Basically, the app would open, and it would be a web view inside of it that we could iterate on quickly and change very rapidly and not have to wait for app store view process to change it. It wasn’t totally a native experience, but it was as actually a pretty good experience and lasted for a very long time and was up until recently the foundation of our current mobile web experience, which is different from our app situation. So for a long time, basically, our app store iOS Instacart app was a wrapped web view of just our store, a condensed version of our store, which meant that we could add things. We could change sales. We could change the formatting. We could change the UI really fast and not have to worry about the app store review process.
This all changed about a year ago, I would like to say, at which point it became a totally native app. We felt comfortable enough with the product and all the features that we made it a native experience and made it a fully featured app.
While the majority of our stack is now using Swift, we still love Objective-C in many cases, especially low-level software manipulation, where it's just easier. It doesn't hurt that a lot of iOS/OS X Libraries out there are written in it either.
We like to go native with iOS development, and Objective-C has been the only game in town until recent introduction of Swift. We're keeping an eye on Swift, but we aren't giving up on the [old way:to do:things]!