High Performance iOS Apps

Chapter 1. Performance in Mobile Apps

This book assumes that you are an iOS developer and have been writing native iOS apps for a substantial amount of time—and that you now want to take the leap from being yet another iOS developer to the top of the league.

Consider the following statistics:¹

• 79% of users retry an app only once or twice if it failed to work the first time.

• 25% of users abandon an app if it does not load in 3 seconds.

• 31% of users will tell others about their bad experience.

These numbers reemphasize the importance of optimizing your app for performance. Getting your app recognized in the users’ view is not just about the functionality. It is about providing a smooth experience all throughout the interaction with the app.

For any particular task, there might be several apps available in the App Store to accomplish it. But users will stick to the one that is either indispensable or has no glitches and stands out from others in terms of performance.

Performance is impacted by many factors, including memory consumption, network bandwidth efficiency, and user interface responsiveness. We will first outline different types of performance characteristics, before moving on to ways of measuring them.

Defining Performance

From a technical standpoint, performance is, strictly speaking, a very vague term. When someone identifies an app as being a high-performing one, we don’t necessarily know what that means. Does the app use less memory? Does it save money on network ...