---
title: "init(format:)"
framework: audiotoolbox
role: symbol
role_heading: Initializer
path: "audiotoolbox/auaudiounitbus/init(format:)"
---

# init(format:)

Initializes a bus object with a specific format.

## Declaration

```swift
init(format: AVAudioFormat) throws
```

## Parameters

- `format`: The initial audio format.

## Return Value

Return Value A newly-initialized bus object, or nil if the operation failed.

## Discussion

Discussion Audio units can generally be expected to support the AVAudioFormat standard format (deinterleaved 32-bit float), at any sample rate. Channel counts can be more complex. See the channelCapabilities reference for a more complete discussion. Initialization will fail and return an error if the specified format is unsupported for the bus. note: In Swift, this API is imported as an initializer and is marked with the throws keyword to indicate that it throws an error in cases of failure. You call this method in a try expression and handle any errors in the catch clauses of a do statement, as described in Error Handling in The Swift Programming Language and About Imported Cocoa Error Parameters.

## See Also

### Audio Unit Implementations

- [supportedChannelCounts](audiotoolbox/auaudiounitbus/supportedchannelcounts.md)
- [maximumChannelCount](audiotoolbox/auaudiounitbus/maximumchannelcount.md)