Debug specific features with Focus, narrowing down the debug output to only the information you need.

In this article:


The Focus feature of Flint allows you to debug more effectively by stripping away all the noise from your logs and the Timeline.

When you tell Flint to focus on one or more specific features, all timeline and logging output will be dynamically filtered to include only entries derived from actions performed on those features. It’s like drinking from a bottle instead of a firehose.

How to change focus

Focus is implemented as a feature inside of flint.

To change focus you perform the focus or defocus actions on FocusFeature, passing in a FocusArea instance that describes you area of interest:

if let request = FocusFeature.focus.request() {
    request.perform(withInput: FocusArea(feature: MyBuggyFeature.self)))


// Revert back to previous focus - probably the firehose
if let request = FocusFeature.defocus.request() {
    request.perform(withInput: FocusArea(feature: MyBuggyFeature.self)))

Disabling the Focus Feature

You can leave focus-changing code like the above in your app, perhaps tailored for different build flavours during development to help reduce noise during a sprint.

Because FocusFeature is a conditional feature the uses the runtimeEnabled constraint, you can entirely disable it at runtime with one line of code:

FocusFeature.isEnabled = false