---
title: start()
framework: foundation
role: symbol
role_heading: Instance Method
path: foundation/nsmetadataquery/start()
---

# start()

Attempts to start the query.

## Declaration

```swift
func start() -> Bool
```

## Return Value

Return Value true when successful; otherwise, false. A query may fail to start if it does not specify a predicate, or if the query has already been started.

## Discussion

Discussion A query can’t be started if the receiver is already running a query or no predicate has been specified. This method must be called from the receiver’s operationQueue or on the main thread. For example:

## See Also

### Running queries

- [isStarted](foundation/nsmetadataquery/isstarted.md)
- [isGathering](foundation/nsmetadataquery/isgathering.md)
- [isStopped](foundation/nsmetadataquery/isstopped.md)
- [stop()](foundation/nsmetadataquery/stop().md)