# App Launch

{% hint style="warning" %}
Starting from **SDK 19.0.0**, we’ve refined how app launch duration is captured for improved accuracy.\
The duration is now measured **from app startup until** `UIApplication.didBecomeActiveNotification` **notification**, which marks the point when the app is fully active and ready to receive user interactions.
{% endhint %}

### Cold App Launch

Luciq automatically measures your **cold app launch** latency, which is the time between when your user launches the app from scratch and when it is responsive and accepting touch events.

It starts with the process start time and stops at the end of the first run loop. This interval accounts for any launch-blocking logic in your code, as well as the time before your app classes are loaded. It includes loading dynamic frameworks and resolving any dynamic references made in the binary.

***

### Hot App Launch

The Luciq SDK automatically measures the **hot app launch** latency, which is the time between the user launching the app from the background and it becoming responsive and accepting touch events.

Hot Launch is transitioning the app from the background to the foreground-active state. We capture the Hot Launch event by observing a `UIApplicationWillEnterForegroundNotification` notification, which is then followed by `UIApplicationDidBecomeActiveNotification`.

***

### End App Launch

In the event that you'd like to define a specific point in time where the app launch can be considered complete, such as when the app is actually interactable, you can use the end app launch API to set that point. You'll then be able to see this data alongside the automatic cold and hot app launches that were captured.

***

### App Launch Apdex

Luciq calculates an Apdex score for your app launch that reflects how satisfying your app launch time is. Your Apdex score ranges between 0 and 1; a higher value means better performance and, hence, a better user experience:

* Apdex score ≥ 0.94 equates to **Excellent** performance.
* Apdex score ≥ 0.85 and < 0.94 equates to **Good** performance.
* Apdex score ≥ 0.7 and < 0.85 equates to **Fair** performance.
* Apdex score ≥ 0.5 and < 0.7 equates to **Poor** performance.
* Apdex score < 0.5 is considered **Unacceptable**.

### How Is The App Launch Apdex Calculated?

When an app launch occurrence is collected, it is flagged based on a pre-defined target (T). An app launch occurrence is considered:

* **Satisfying:** if its duration ≤ T
* **Tolerable:** if its duration > T and ≤ 4T
* **Frustrating:** if its duration > 4T

Then, based on the bucketing explained above, the Apdex score is calculated as follows:

* Total occurrences = Satisfying occurrences + Tolerable occurrences + Frustrating occurrences
* Apdex score = (Satisfying occurrences + 0.5 \* Tolerable occurrences) / Total occurrences

### How Can You Control Your App Launch Target?

By default, the target is set to **0.5 seconds**; however, you can easily change this number from your dashboard by clicking on the action highlighted in the screenshots below.

<figure><img src="https://files.readme.io/9ce338e1c64c01dd74ae950402ba91e6081478cfc3dace12b405d3ff14aa1d09-image.png" alt=""><figcaption></figcaption></figure>

{% hint style="info" %}
Please note that updating your app launch target does **not** affect the already stored occurrences; only future occurrences will be flagged using the new target.
{% endhint %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.luciq.ai/product-guides-and-integrations/product-guides/application-performance-monitoring/app-launch.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.