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Feature Flags Demystified: A Swift Developer’s Guide (with Firebase)

Steven Curtis
Firebase Developers
6 min readJul 23, 2024

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Photo by Hossein Nasr on Unsplash

I’ve been coding iOS Swift apps for a while. I’ve been writing articles for a long time. I just realised that I’ve ignored feature flags (also known as feature toggles).

So I’ve used Firebase to implement them in a sample project. They work great and mean that you’d be able to turn features on or off without code deployment or releases. That’s something you’d probably want in a production app, so let us get on with the proof of concept!

Feature Flags? What’s That?

Feature flags are also known as feature toggles.

Using feature flags enables continuous integration and delivery, so code can be merged into the main branch without immediately being avaliable to users. That is, new code is behind a feature flag so will only be made available to users when we are ready to release.

This facilitates A/B testing and gradual rollouts. Experiments can be run to decide whether one version of an app is truly better than another. If a feature is broken for some reason we also have the safety net of being able to disable features.

Of course most of this is only true if the feature flag can be controlled remotely, that is from outside the target app. That’s…

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Firebase Developers
Firebase Developers

Published in Firebase Developers

Tutorials, deep-dives, and random musings from Firebase developers all around the world. Views expressed are those of the authors and don’t necessarily reflect those of Firebase or its parent companies.

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