7 Critical Things to Know When Building Any Mobile App

This blog post builds on concepts proposed in an earlier post about not all mobile apps being created equally. If you are a developer who is in the process of migrating to mobile this post is for you. It’s intended to raise awareness of important items to consider in your requirements. My goal is to help you identify some of the major gotchas early on in the development process and improve your chances for success.

There are many more details to learn on the topics I’ve described below. The good news is that in the last few years the amount of deeply helpful documentation has expanded considerably. Where possible I’ve tried to include links related to each topic.

Touch-based Workflows. Recent research has shown that people use their smartphones more often than web apps, and they spend roughly 80% of their time on social media and games. Because of this and the fact that smartphones today are touch driven and not mouse driven, you have to take that into account in your user interface design. Touch implies many things including gestures and multi-touch. You can toss your old conceptions of user interface design based on desktops and tablets, and check out Android’s recommendations as well as Apple’s. My strong recommendation is to hire a UX designer to help you through building a user interface.

Mutliple form factors come with various screen sizes and densities. Long gone are the days of building for just three main browser types. Now you have to take into consideration iPhones, iPads, tablets, numerous different style androids as well as desktop and laptops. Android defines the following screen sizes and, as you can see, this is quite varied and smaller than a typical laptop or desktop. Those typically run 1024 x 768 or greater.

  • xlarge screens are at least 960dp x 720dp
  • large screens are at least 640dp x 480dp
  • normal screens are at least 470dp x 320dp
  • small screens are at least 426dp x 320dp

This is important to know because an app that looks good on an iPad may not look good, or display correctly, on the four inch display of a Motorola Atrix at 960 x 540. A button that looks correctly sized on one smartphone may look too big on another. A whopping 84% of all Android screens are what Android defines as normal size (>=  470dp x 320dp) and between either medium dpi (~160dpi) or high dpi (~240dpi). But, you still have to take into consideration other densities. I also recommend taking a look at new HTML5 browser-based technologies to help with addressing this problem, such as CSS media queries.

Inconsistent Internet. It’s a best practice to check if internet connections exist and gracefully handle HTTP requests when the internet is down, as I blogged about here.  Depending on your application and needs, you should also monitor whether or not a wireless connection can be made and then allow the application to switch to wireless where possible. Wireless also has the advantage of using less battery power.

Slower Connections. And, on a related note, you can’t always depend on 4G connections having consistent maximum download speeds. Over the course of a user session, the connection speed will vary widely and you should plan for that. I’ve been trying to find some stats on mobile internet quality world-wide, if they are out there they are hard to find. But, we’ve all experience spotty mobile internet coverage. Take this into account if you are transferring large amounts of data between your servers and your app. You should also consider detecting when the user is in an area of greater bandwidth and use that to download more data less often. Use loosely coupled and event driven architectures. Test app load times on various devices and around town and away from your office.

Less CPU Horsepower. While the latest generation of four core phones are certainly the most powerful phones yet. In general, applications and web pages will run slower on phones than they do on your development machine running a desktop browser. Take older generation phones into account because they are usually significantly slower than the newer phones. There are a few workarounds in HTML5 to help with this, in that done correctly they can offload rendering to the hardware. In native applications be aware of memory leaks because, remember, more memory usage means less battery life and applications that can run slower over time.

Support across multiple operating system versions. Remember on Android that the vast majority of users are still running v2.2 – v2.3.7 even though v4.x is currently shipping. You’ll have to do some research on your target market and find out what versions and type of phones they are using. You can’t support everything, but you can make educated guesses. Apple, on the other hand, has a significantly more limited selection of phones and tablets that you have to support, and they do a great job helping you support those.

There are some solutions that help with building cross-platform mobile apps, to go into more detail will take another blog post. Here’s a few: Adobe Flex, PhoneGap and Titanium. Keep in mind that the future of Flex, as a development platform, is being called into question after Adobe open sourced everything but the browser and desktop runtimes to the Apache Foundation. PhoneGap and Titanium offer what is now being called “hybrid” solutions where you can build an application in JavaScript, for example, and then compile that code for native deployments on Android and iOS.

Battery Life. Ah, battery life is last but certainly not least. Be aware of how battery intensive your application is and try to minimize battery consumption as much as possible. The Android online docs have a number of highly information articles on this subject. Smaller app footprint in memory means less battery consumption. Heavy CPU usage means more battery usage. Minimize GPS usage through smart algorithms to help preserve battery life.  Switch to 802.11 wireless connections where possible, since this requires less battery power than 3G and significantly less power than 4G.

So, there you go. I hope these suggestions help. If you have more suggestions based on your own experience please post a comment!


Android Gestures

Android Optimize Battery Life

Android Screen Sizes and Densities

CSS media queries

Android UI Design

Android Model for Best GPS Performance

iOS User Experience

HTML5 Hardware Acceleration

Event-based Architectures for Adobe Flex

So you want to build a mobile app? Not all mobile apps are created equally

Most smartphones users I know ditch apps pretty quickly if they don’t work or end up being clunky. So, if your company is considering offering mobile apps to your customers you should be aware of a few things.

Buy a Smartphone. If you don’t already have a smartphone then you should go out and buy one. Then download a number of apps that interest you and try them out and see what you like and what you don’t like. For example, if you do the shopping for your family you might consider trying out a bar code scanner app that lets you compare pricing. Some scanner apps may work faster than others. If you don’t own a smartphone then you won’t be able to understand what a good app is.

Likes and Dislikes. Pay close attention to what you like and don’t like about a particular app. Here are a few questions to take note of:

  • Was it easy to use?
  • Did it hang and/or crash?
  • Did it perform its tasks gracefully?
  • Did it do what you expected?
  • Was it visually appealing?

Become Tech Savvy. Become a bit more tech savvy about things that the phone is doing behind the scene. There are apps that do this for both Android and iPhone that help you monitor what’s going one. Things to look out for:

  • Apps that keep running even after you think you shut them off. These will run the battery down faster.
  • Apps that consume more and more memory over time. Using more memory equals more battery usage and shorter time between charges.
  • Apps that seem to slow your phone down when they run. These apps may be using more CPU than necessary resulting in greater battery usage.
  • Apps that connect to the internet frequently costing you extra data charges. There are apps that let you monitor how much data your phone uses and some apps can help pinpoint which apps use the most data.

Which Phones to Support? Understand what devices to support. If you are building an application for internal use, then you have an easier decision since you hopefully have some control over which devices are being used and how often their software gets updated. If you work in retail, your users may have Androids, Blackberries, iPhones, iPads, Kindle’s, Nook’s and possibly other tablets that get updated whenever and however the customer dictates. My advice is do some research and pick one that is used the most and work on that first.

Release Early and Iterate Often. Technology changes so quickly these days that if your app takes more than 3 – 6 months to build, then the technology will change underneath you. In other words, you might be releasing an application that doesn’t work perfectly with the latest phone operating systems or browsers that your customers are using. When that happens, it will cost you even more time and money to fix the problem and the problem will repeat itself. Be sure to take into account the speed at which technology will change once you begin your software development process.

Go Native, Go Web Browser, or Both? Last, it’s important to understand that there are two common types of mobile applications. Native apps are downloaded from an app store and installed directly on the phone, the other is a web app that runs in the phones web browser. My advice is to research and understand your target market. What do your competitors use? What do your customers prefer? What are the trends in your industry?

If you go with native apps, you’ll need to understand which phones to support and how often you will be updating the app. If you choose web apps you’ll need to know which browsers to support. Also take into consideration which skill sets your development team has and understand if they can tackle the project or if you need outside help.

Update, Update, Update. No matter what you decide, you can’t just deploy an app and think you’re done. If you want to keep your customers happy, you’re going to have to keep updating the app until the product line is discontinued or replaced. And, you have to update it often enough to stay on top of the latest technologies. New smartphone models are being released all the time and they all may have different screen sizes and screen resolutions. An app that looks good at one screen size may look horrible on a tablet or iPad. These things have to be accounted for. And, the smartphones operating system software may be updated three or more times per year offering new functionality and fixing bugs. If your customers download a broken app, or if they see the app that hasn’t been updated in a while and something stops working they may not be your customers for much longer. This is especially true for retail apps where customers make split second decisions whether to stay or walk away and try something else.

Conclusion. I hope you find this list useful and at least give you some ideas to think about before you dive head first into bringing a new mobile application into the world. It can be fun, be there is a lot of hard work involved. But, if you plan it right you’ll be successful and learn alot in the process!

Fastest Android Wall Charger?

I accidentally discovered that the fastest charger for my Motorola Atrix so far is actually a Barnes & Noble Nook charger. I’m blogging about this because the charging time of Atrix is a major point of contention, and it drives me crazy.

My Atrix takes forever to charge with the Original Equipment (OEM) factory charger. For the record, I’ve never been impressed with Micro-USB chargers. If the battery is around 30% – 40% when first plugged into the charger, it takes up to 5 – 6 hours to reach a full charge. This is painfully long especially in comparison to my retired Google Ion that always seemed to get fully charged in less than an hour. Often-times I walk-around with a half-charged phone because every time I pull it off the charger to go to a meeting, it has only charged a fraction of a percentage more than it had an hour earlier.

I’ve tried a number of different chargers including ones from my HTC EVO. Then at a recent out-of-town trip, I lost my factory charger and decided that since the Nook charger had the same type of USB plug, same voltage and amperage rating that I’d give it a try. At the time that seemed better than running out and buying a new one at the AT&T store. What happened next really surprised me. The Atrix charged from 50% to 100% in about two hours. In general, this charger consistently charged my phone faster.

Now before you blast me about slow chargers are the best way to go, keep in mind this was just an experiment and this post comes with a large amount of CAVEAT EMPTOR:

  • WARNING – Motorola ONLY recommends using approved chargers with their phones, so if you mess up your battery or phone don’t blame me. Furthermore, if you run out and purchase a Nook charger there is no gaurantee it will perform the same.

If you’ve had any better/different experiences with other charges please post a comment.


Barnes & Nobel Nook Charger – Model No. BNRP5-850, Output: 5v @ 0.85A