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# init(length:)

Initializes and returns a mutable data object containing a given number of zeroed bytes.

```
init?(length: Int)
```

## Parameters

`length`

The number of bytes the object initially contains.

## Return Value

An initialized `NSMutableData` object containing `length` zeroed bytes. The returned object has the same memory alignment guarantees as `malloc(_:)`.

## See Also

[`+  dataWithCapacity:`](/documentation/Foundation/NSMutableData/dataWithCapacity:)

Creates and returns a mutable data object capable of holding the specified number of bytes.

[`+  dataWithLength:`](/documentation/Foundation/NSMutableData/dataWithLength:)

Creates and returns an mutable data object containing a given number of zeroed bytes.


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