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# init(format:)

Initializes a bus object with a specific format.

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

## Parameters

`format`

The initial audio format.

## Return Value

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

## Discussion

Audio units can generally be expected to support the <doc://com.apple.documentation/documentation/AVFAudio/AVAudioFormat> standard format (deinterleaved 32-bit float), at any sample rate.

Channel counts can be more complex. See the [`channelCapabilities`](/documentation/AudioToolbox/AUAudioUnit/channelCapabilities) reference for a more complete discussion.

Initialization will fail and return an error if the specified format is unsupported for the bus.

> Handling Errors in Swift:
> 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](https://docs.swift.org/swift-book/LanguageGuide/ErrorHandling.html) in [The Swift Programming Language](https://docs.swift.org/swift-book/) and `About Imported Cocoa Error Parameters`.

---

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