---
title: start()
framework: classkit
role: symbol
role_heading: Instance Method
path: classkit/clsactivity/start()
---

# start()

Tells an activity to start recording duration and progress for a task.

## Declaration

```swift
func start()
```

## Mentioned in

Recording student progress

## Discussion

Discussion Beginning in iOS 11.4, you can start more than one activity at a time, each in its own context. This allows you to nest activities, running a given context and all its ancestors simultaneously, thus measuring progress at multiple levels of context hierarchy concurrently.

## See Also

### Starting and stopping an activity

- [stop()](classkit/clsactivity/stop().md)
- [isStarted](classkit/clsactivity/isstarted.md)
- [duration](classkit/clsactivity/duration.md)