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# AVMutableMetadataItem

A mutable metadata item for an audiovisual asset or for one of its tracks.

```
class AVMutableMetadataItem
```

## Overview

You can initialize a mutable metadata item from an existing [`AVMetadataItem`](/documentation/AVFoundation/AVMetadataItem) object or with a one or more of the basic properties of a metadata item: a key, a key space, a locale, and a value.

## Topics

### Creating a metadata item

[`metadataItem`](/documentation/AVFoundation/AVMutableMetadataItem/metadataItem)

Returns a new mutable metadata item.

### Identifying metadata items

[`identifier`](/documentation/AVFoundation/AVMutableMetadataItem/identifier)

Indicates the identifier of the metadata item.

### Accessing keys and key spaces

[`key`](/documentation/AVFoundation/AVMutableMetadataItem/key)

The key for a mutable metadata item.

[`keySpace`](/documentation/AVFoundation/AVMutableMetadataItem/keySpace)

The key space of the metadata item’s key.

### Accessing values

[`value`](/documentation/AVFoundation/AVMutableMetadataItem/value)

The value for the mutable metadata item.

[`extraAttributes`](/documentation/AVFoundation/AVMutableMetadataItem/extraAttributes)

A dictionary of additional attributes for a metadata item.

[`dataType`](/documentation/AVFoundation/AVMutableMetadataItem/dataType)

The data type of the metadata item’s value.

[`stringValue`](/documentation/AVFoundation/AVMutableMetadataItem/stringValue)

The value of the metadata item as a string.

[`numberValue`](/documentation/AVFoundation/AVMutableMetadataItem/numberValue)

The value of the metadata item as a number.

[`dateValue`](/documentation/AVFoundation/AVMutableMetadataItem/dateValue)

The value of the metadata item as a date.

[`dataValue`](/documentation/AVFoundation/AVMutableMetadataItem/dataValue)

The value of the metadata item as a data value.

### Accessing timing

[`time`](/documentation/AVFoundation/AVMutableMetadataItem/time)

The timestamp for a mutable metadata item.

[`startDate`](/documentation/AVFoundation/AVMutableMetadataItem/startDate)

The start date of the timed metadata.

[`duration`](/documentation/AVFoundation/AVMutableMetadataItem/duration)

The duration of a mutable metadata item.

### Accessing language support

[`locale`](/documentation/AVFoundation/AVMutableMetadataItem/locale)

The locale for a mutable metadata item.

[`extendedLanguageTag`](/documentation/AVFoundation/AVMutableMetadataItem/extendedLanguageTag)

The IETF BCP 47 (RFC 4646) language identifier of the metadata item.


---

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