Finding the Right iOS Dev

Over the past few weeks I've had a few friends and colleagues ask me about the iOS developer interview process -- both on the interviewer and the interviewee sides. Having sat on both sides of the table, this post is a collection of thoughts on how to find the right developer for the job. I should note that these opinions are entirely my own and are completely subjective.

First, I think there a few things to consider before diving straight into interview Q&As -- there's a lot more to it than just rattling off a list of Objective-C programming questions found from a Google search. Yes, that can help you find smart engineers, but it might not get you the whole picture. Here are a few main points to consider when looking at a candidate:

  • Published work
  • Knowledge of Objective-C and Cocoa Touch
  • The right ratio of hackerness vs convention-use
  • Online reputation*
  • Overall tech savviness

Published work

You'll want ask for examples of published work. While at Cocoa Camp last summer I noticed several things that Apple looks for in a perspective engineer. Here are two from my notes:

  1. Someone who is driven to learn - and ship.
  2. Someone who has an obsession with creating - and delivering.

There are lots of extremely talented computer scientists and web developers in the world, but it takes a unique blend of hard-skills and finishing ability to make a good iOS developer. While pet projects are nice, that alone shouldn't impress you. Half-baked ideas are just that, half-baked, and not something you want to publish as your company's next app. Looking at the candidate's apps on the app store will tell you more about their experience level than their resume ever could. If their work was written as a team effort, ask them which pieces they developed or what percentage contribution they made to the overall app.

Knowledge of Objective-C and Cocoa Touch

You'll want to be sure the person has a solid understanding of programming principles, design patterns, Objective-C, and the Cocoa Touch frameworks. The depth of knowledge and understanding required will vary depending on the experience level you're looking for and how much you want to pay, but here are my suggestions for a good junior-level iOS developer.

  • MVC pattern - Ask the candidate to include an example or explanation of how they've used it in an app. 
  • Protocols and delegates - Ask the candidate "why are delegates protocols?" (and not normal classes). What I would look for is that the candidate can explain that protocols are more flexible than a normal class, because they can be implemented by any class, allowing for greater reuse. If they can explain this to you, in addition to the general idea behind the delegation pattern, that's a good sign.
  • Strong vs weak pointers - What's the difference? When would you use one vs the other?
  • Check out Ray Wenderlich's post on iOS interview questions.
  • Any questions specific to your project, code base, or existing development team that can help determine if this person is the right fit.

Hackerness vs Convention-use

I'm not sure what else to call this one. Objective-C is a very convention heavy programming language. If the candidate is a recent transplant from another development stack or a hobbyist iOS developer turned professional, they may not have fully embraced the Objective-C way (no ill-will towards these groups, I came in with almost exclusive Java/Android experience when I started with Objective-C). There are always opinions when it comes to code formatting, design patterns, and naming conventions, but with iOS in many cases there is a recommended best practice that should be followed.

You might be thinking "so what if they do it their own way, so long as it works" (especially if you're just looking for a temporary contractor). Wrong! No matter how small you think your project will be, there are going to be changes to be made down the road. And who's going to read that code? It might be the original developer, or it might not. Use of conventions allows for easier readability and better maintainability, and will lower your switching costs if the original developer doesn't work out or decides to suddenly leave for another gig.

If you yourself have a good knowledge of iOS development, brush up on your Cocoa Coding Guidelines and ask for a code sample. Look at things like use of class prefixes, method names, constants, and categories. Ask the candidate about software design. Do they design their code for personal use, quick-and-dirty, never to be touched again, or do they design their code with reusability and efficiency in mind. One of the best signs of a modern programmer is that they design their code -- internal and external -- as if it were an externalizable service - taking a page of Amazon's book. A code sample can also be useful to see their design style and identify particular areas of focus (e.g. networking, UI, data persistence, animations, etc).

Online Reputation*

I put an asterisk next to this one because I think this might be the most debatable point. For me personally though, I give bonus points for active use of GitHub, StackOverflow, App.net, and Twitter (unless its to manage a Biebs fan handle). Open-source software is huge both in web and mobile. If the candidate is familiar with pulling code off GitHub (properly attributed of course), it could definitely come in handy in the future. Better still if the candidate has contributed to open-source projects or created one of their own.

Completely on the other side of the coin, I know several excellent developers who don't care much for social media or personal branding. It's no knock on them, it's just not in their interests. That's fine too, just be aware of it and make sure the candidate is a good cultural fit for your team. e.g. if you're launching a social network for chihuahuas and the candidate isn't active on Facebook, Twitter, or Instagram, it's probably not the best fit even if they are extremely smart.

Overall Tech Savviness

Lastly, and you've probably done this by now, Google search the person's name and see what turns up. In emails or an interview ask them what they like about programming, iOS, and technology. You know this, but design is HUGE in mobile app development. It should be a big deal to the interviewee. UI/UX will make or break your business, so make sure you value this appropriately. I love that in a mobile developer job posting for Alpine Replay, their "next steps" are simply:

  • "Send us an email. Please include some of your sample work, a collection of your favorite designs (not yours) and whatever else you feel may be applicable."

A savvy design enthusiast who's up on the latest trends and upcoming iOS 7.1 or iOS 8 features could help take your app's user experience to the next level.

Disclaimer

All the suggestions in this post are personal opinion. Any and all of it should be adjusted to fit your needs and your team's culture.

Why singletons are bad

Disclaimer: This isn't a total knock on singletons. Alternate title: "Why singletons can be bad".

Software Design

Yesterday I had a conversation about software design with an experienced colleague and found myself reaching when discussing design patterns. Specifically, we got onto the topic of the singleton pattern. 

Knowing from recent experience at Cocoa Camp that singletons are not the end all be all solution for object oriented programming (yes, I might have thought that at one point), I was careful not to sound overly enthusiastic that I used the singleton pattern. I first learned about the singleton pattern in an Android development college course that I took in Winter 2011. It sounded pretty cool then, and it was even a semi-significant part of the midterm. I later began learning Objective-C, and after using the pattern in a few iOS apps over the past year - including collaborative projects with other developers who hadn't ever mentioned any negatives in the singleton pattern - I had gradually assumed that they were a pretty solid way to go. Last month at Cocoa Camp the pattern came up and although we didn't get into any detailed discussions on it, I got the impression that singletons weren't as favorable as I had thought... 

Back to our conversation, I mentioned that I knew singletons had positives and negatives and explained a little more about why I'd used them in the past. He pried pried a little deeper, asking two questions that I want to expand on. "What are some of the downsides to the singleton pattern?" "What alternative design patterns would you suggest?" I mentioned a few things, including keeping the object in memory for the entire life of the application, rather than when specifically needed, and that an alternative method could be to pass the data between view controllers rather than via the shared singleton instance. Then we moved on.  Conversation over.

Why singletons are bad

Later (okay, ten minutes after the conversation ended), I found Steve Yegge's blog post, Singleton Considered Stupid:

Begin Quote 

Here's what most people got out of Design Patterns: "blah blah blah blah SINGLETON blah blah blah blah". I kid you not. I've seen this so many times that it's become a full-fledged pattern in its own right; patterns need a name, so let's call it the Simpleton Pattern.

The Simpleton Pattern unfolds like this:

Me: So! Have you ever heard of a book called Design Patterns?

Them: Oh, yeah, um, we had to, uh, study that back in my software engineering class. I use them all the time.

Me: Can you name any of the patterns they covered?

Them: I loved the Singleton pattern!

Me: OK. Were there any others?

Them: Uh, I think there was one called the Visitater.

Me: Oooh, that's right! The one that visits potatoes. I use it all the time. Next!!!

I actually use this as a weeder question now. If they claim expertise at Design Patterns, and they can ONLY name the Singleton pattern, then they will ONLY work at some other company.

End Quote

I really hope I didn't fall into this category in the mind of my colleague, but wow was I unprepared for those two questions. Especially the second question. There are few design patterns with a name as catchy as the singleton pattern. There certainly are other ways and methodologies to accomplish a programming objective, but what's the catchy name for instance classes, interfaces, and passing data between controllers?

I've done some more reading and in hopes of getting it right the next time, here are some of my thoughts.

What do you think are some of the downsides to the singleton pattern?

There are actually a ton. The reasoning is pretty straightforward and I don't know why I didn't think of these earlier.

  • A shared singleton class requires that memory be in use throughout the entire application, even when the object isn't needed.
  • Singletons hide dependencies!
  • As a result of these hidden dependencies you can lose track of the coupling. Instead of meticulously passing each object you need (and only the objects you need) into a function, you instead call [AppUser sharedAppUser] to access your shared instance. While it feels cleaner since it can mean less lines of code to get the access you need, you can end up with very tightly coupled code.
  • You can't (really) subclass a singleton
  • Singletons are hard to test! (1) With hidden coupling it's difficult to create mock objects and (2) singletons generally exist for the lifetime of the app which presents a problem for unit testing, as each unit test should run independently of other unit tests.
  • Just think of it as the "global-ton" pattern. The name isn't that far off. Does it still sound as sexy? 

There are some upsides too, but I'll save that for another time. 

What alternative design patterns would you suggest?

  • Object oriented programming. This isn't just a snarky answer. Use instance classes that are instantiated within the scope that they are needed and pass those objects between methods or controllers as necessary. 
  • Create the instance of your object only within the scope that is needed (be careful not to abuse the AppDelegate).
  • Use dependency injection to pass a single instance of the object to the components that need it (like your unit tests).

Takeaway

      Be smarter. Understand what is actually happening when you use the singleton pattern. As tempting as slapping in SynthesizeSingleton.h into an iOS project is (see http://www.cocoawithlove.com/2008/11/singletons-appdelegates-and-top-level.html), it is NOT the solution to all your problems. You may not need it at all. Tightly coupled code can be a major problem with singletons, and chances are you probably aren't unit testing (or not properly anything) whichever objects you've transformed into singletons ...which you should fix. Most of all, if you enjoy software design but can only list of the singleton pattern when trying to have an intelligent conversation about design patterns, you have homework to do.

      Sources / Related Material

      Growing Pains is Making a Comeback

      If you know me personally, you probably knew that I worked on an app called Growing Pains for last year's BYU Mobile App Competition. It's a photo journal designed to help you easily capture photos of your growing child. The interface is designed to allow you to quickly browse through and see your child's growth over various time periods (ideal for newborns and toddlers -- or puppies). While Growing Pains was a success in the competition, winning over $2000 value in awards and placing 5th overall, unfortunately it has not yet seen the light of day.

      A partner on the project and I have been talking recently about bringing it back to life, and last week while at Cocoa Camp Apple challenged us to bring our own ideas to work on, so I did just that. On Monday of last week I ctrl+shift+N'ed a new project in Xcode and started clean. Did this for several reasons, firstly, because Cocoa Touch changes so much from year to year that I'm sure our existing code base would require some amount of updating to get in line with the latest conventions and best practices. Secondly, and the bigger reason, is that while SDK changes have been semi-significant, changes to iOS design patterns have been EXTREMELY significant. Take the example below.

      You've probably seen and heard all about iOS 7, so I'll save my personal thoughts on the change for another discussion, the important points to note are the focus on simplicity, utility, and depth. With the greater population generally familiar with smartphones, as an app designer & developer I can now eliminate the use of some of the more cutesy effects that previously communicated "tap here", "I am a menu", "this is a button", and so on. Apple has also stressed depth in the new design, despite it looking more flat than before. By adding blurs, realistic motion effects, and new levels of perspective, iOS 7 is inherently more realistic than before, albeit far less skeuomorphic.

      Growing Pains is now undergoing its own transformation from the old world to the new. Here are a few of the design concepts for the new UI, shown alongside the original designs. Please feel free to jump in if you have any thoughts or suggestions. These designs are being iterated on almost daily at this point.

       

      What do you think? Are there any elements of the old design that you like better, or feel are missing in the new versions? Is it any more or less intuitive than before?

      Maybe Microsoft is doing it right. Or maybe they're not.

      Dell Venue Pro, running Windows Phone 7.5

      Since I first began seeing concepts of Windows 8 I kept thinking, huh, maybe Microsoft is onto something here. Despite being both an Android and an iOS fanatic, I have been impressed with the Windows Phone OS since trying out Windows Phone 7.5 from Dec 2011 - March 2012 on an extra Dell Venue Pro my dad had available. The hardware was...a brick... to put it nicely, but the OS itself was excellent. 

      Over the last 18 months I've found myself continuously (and to my friends' amusement) defending Windows Phone as a viable mobile operating system, and, as an extension, defending Windows 8. I've gushed over the Lumia 920, HTC 8X, and now the Lumia 1020. I almost bought all three of these devices on numerous occasions (just ask Dru). While I maintain that Windows Phone is a great OS, I'm coming to terms with the idea that maybe Microsoft isn't doing it right and that they did in fact jump the gun on the idea of the convergence of the desktop and the mobile experience. Since MS's release of Windows 8 there's been talks of how revolutionary and visionary it is. Ahead of its time. Some referred to it as showing that Microsoft had not only caught up to Apple and Google, but far surpassed their ability to deliver innovative products that end users didn't even know they wanted until they tried it (take the iPad for example).

      Well, after a year of saying to myself, yeah, maybe they did get it right, maybe Windows 8 isn't as radical as all the critics say, maybe we will all be using touchscreen desktop computers in a couple years, I'm now saying maybe not. 

      The truth is that the people don't want the same experience on a tablet as they have on their desktop or laptop. Sure, they like familiarity, but at the core a user's interaction with a tablet and user's interaction with a desktop computer is just different. And people are fine with that. The design of an application on the desktop environment is (and should be) vastly different than the tablet and the phone representations of that same application. Probably one of the best examples of this is the Day One app for iPhone, iPad, and Mac. Ask any active Day One user if they'd like to combine either the iPhone and iPad experience or the iPad and Mac and they'd look at you like you were crazy.

      Day One for iPhone, iPad, and Mac

      Further evidence that people just don't want to merge desktop computing and mobile computing... look at this Acer commercial comparing their 8" Windows tablet to the iPad mini. This is my opinion, and I bet some Windows 8 fans view this commercial as a win for Acer and Windows 8 Pro, but firstly, who wants to play Halo on a tablet (not that they even look like they're actually playing...)? Don't get me wrong, I love iPad games... Plants vs. Zombies vasebreaker endless mode... that'll keep me busy for HOURS. But I don't really care for the idea of getting a dumbed down PC gaming experience on my iPad. Maybe if the entire game was reimagined for iPad, and it really was just a distant relative of Halo, but the ability to run full-fledged PC games on a tablet just doesn't do much for me. Okay, next flaw in the video, of all the things you can do on a tablet, why show someone accepting changes to a Word doc? I mean, seriously, of all the things I've used a tablet for (thinking my Kindle Fire, Nexus 7, and iPad), I have never once wanted to accept changes to a reviewed Word doc. And if I did, I wouldn't want to be using the traditional Word app to do it (see all those tiny touchpoints?!).

      UPDATE: I hadn't done my research on Halo Spartan Assault, and it looks like it very much is  the Halo experience reimagined for touch. That's cool. What I was trying to get at is the idea of playing traditional PC games on a tablet running Windows 8 Pro.

      What I'm getting at (and have probably repeated 20 times by now) is that I no longer believe that we are heading in the direction of an integrated desktop and mobile computing environment. Those who never got on the Windows 8 bandwagon are probably thinking, yeah, knew that all along. But for those who have seriously entertained the idea of everything converging into a single, universal experience, either the timing is wrong or the implementation is wrong. Either way, maybe Microsoft isn't doing it right after all.

      Testing in iOS

      I’ve been researching Continuous Integration (CI) and unit testing in iOS lately and learning a lot about testing your application. So far, I’ve learned how to write unit tests in Xcode, some basic guidelines for writing those tests, and experimented with Jenkins CI server to create automated builds, tests, email notifications, and archives. This post is meant to be a collection of my thoughts and takeaways.

      Two Types of Unit Tests

      The are two main types of unit tests in objective-c, logic tests and application tests. There also two general approaches to unit testing, which happen to correlate: bottom up and top down. In bottom up testing, you look test each method or class individually, entirely independently of each other. In top down testing, you test the functionality of the app as a whole.

      Because your logic tests are independent of each other, they can run without needing the context of your application’s controllers or views. Logic tests can only be run on the simulator. Application tests are (appropriately) run in the context of a host app, and can be run either on a device or in the simulator.

      Efficiency in Unit Testing

      After figuring out a how to create unit tests, run them, and seeing the little green checkboxes telling me they passed my first reaction was to get a little unit-test-happy. I was thinking oh, I can test this, and that, and all of that… Well I’m finding that there’s a balance between efficient, high-quality unit tests and simply testing every single input and output.

      When you test parsing a JSON response from your server, for example, ONE way to do it is to assert that the final property value is equal to the original value in the JSON. There are however, many more ways to test your parsing and relational mapping. You might try testing for valid data using character sets, checking string lengths are greater than zero, or that birthdates are before today’s date. Then, try 4 or 5 different data sets, rather than a single one.

      Basically, rather than test for a specific outcome with your logic tests, be a little more broad. Trying to test for a very specific output might be beneficial in some cases, but it can quickly become tedious and time-consuming. Testing for types of data, unsupported input characters, and invalid states can cover more errant cases in less time. Significantly less time.

      The Sweet Spot 

       

      image-thumb1.png

      I found this graphic in a blog post about unit testing best practices  about halfway through my research and was really glad I did. Essentially, unit tests should hit the sweet spot of testing individual units (bottom-up) or testing the entire system (top-down) and not fall into a dirty hybrid that only costs additional time and effort without proving much.

       

      RestKit - Load data from local json file

      I've found that it can be very helpful to be able to load data locally rather than from a server, especially for testing and for situations where you don't have control over the availability or stability of the server side. This code sample shows how, using RestKit, you can load json directly from a file. If you knew what the expected server response was, but didn't have access to the server, this would allow you to put all the object mappings in place and load your object in without requiring a live server. https://gist.github.com/kyleclegg/5846568

      iOS Final Exam

      In 3 hours do: 1) download and parse json for version number and location of zipped sqlite db file 2) if first time or newer version than previously downloaded, download zip using a progress indicator 3) save zip to device documents folder 4) decompress zip file and save 5) delete saved zip file 6) open connection to db, query last updated time and display

      Recommended frameworks: afnetworking ziparchive sqlite

      and the result.... http://screencast.com/t/UXm4kHuMnuq. i didn't have time to make it look pretty, but I finished all 6 tasks. it took every minute of those 3 hours, but I'm pretty proud of it. :0

      Android Thoughts

      Recently a friend decided to upgrade from an Android device to an iPhone 4s. I commented on her facebook post:

      You're crossing to the dark side??

      Kyle youll be back to the dark side iphone is taking over the world!!!! and i want to be on team apple when that happens.

      Touche. can't argue. iphone is by far the best. Android is decent but given iOS and apple hardware as an alternative it's almost a no brainer. unless windows phone 8 makes a splash...

      Someone else chimes in:

      Almost a no-brainer... but not quite. Compared to budget Android devices, the iPhone is definitely superior. But there is literally no hardware spec on the iPhone that isn't matched or beaten by higher end Androids. If you favor features over price point, it comes down to preference, not superiority. The user experience on Android 4.0 is absolutely amazing, and the open source nature of Android puts it light years ahead of iOS in terms of development opportunities.

      Again, it's about preference. iOS is clean, simple, and beautiful. Android is powerful, customizable, and versatile. It's all about what you're looking for in a phone. But let us be wary of granting to Apple some of these unearned superlatives.

      My latest thoughts on Android:

      I haven't used Android 4.0, but given the improvements between 2.2, 2.3, 3.0, and similarly positive and 'groundbreaking' reviews for 4.0, I can't imagine it being something I get too excited about. I switched from an iPhone 4 to Android (dual core Motorola Atrix) for many of the reasons listed but have ultimately been let down.

      Google delivers power, customizability, and a sense of freedom on Android devices, however I find the power comes with some catches - weak battery life, unexpected FCs, laggy display (WHY?? the Atrix's processor should kill the iphone 4). The customization options are confusing and inconsistent across different hardware makers. Even having developed two Android apps, I haven't seen (or maybe just haven't utilized) any features that I feel are compelling. Lastly, the freedom I feel due to the open source nature of Android is refreshing, but honestly, I'd be fine giving up this flexibility for a superior WP7 or iOS device.

      To me, bottom line is the Android ecosystem is discombobulated and inconsistent. It's a decent OS and beats any feature phone on the market, but having seen both Android and iOS up close and personal, I'm ready to switch back to iOS or try something new in WP7/WP8.