Apple has implemented in iOS privacy guarantees long so that users can feel much safer when saving your files or personal data. So when an application requests access to contacts, calendars, photos or our location, a dialog box appears asking the user express permission. IOS 9 and earlier versions of software, however, this warranty does not extend to the multimedia library of a device.
One of the developers of Apple, Ben Dodson, addressed to users in reference to privacy concerns in a blog post in January and said the following
"I have discovered that there is a prompt privacy when a developer tries to access the library. In fact, you can access all the music data. This process happens silently and in my tests I could place a library of 10,000 songs, put all metadata in a JSON file, and upload it to a server in less than 2 seconds. "
Apple acknowledged the problem earlier this year and now has introduced a new key called cocoa NSAppleMusicUsageDescription that developers should be used in all applications that access the media library of the new iOS 10 or later. With this change, the company ensures that users have to grant permission for an application to access the music library.
This new feature allows to describe the reason that the application wants to access multimedia library user. When the system prompts the user for permission to access the value that is provided for this key is displayed as part of the alert.
To protect user privacy, an application for iOS linked from the new IOS 10.0, and has access to the media library, you must declare statically intend to do so. In addition, you must also include the NSAppleMusicUsageDescription key in the Info.plist file for your application and provide a chain for the purpose of this key.
If the application attempts to access the media library without a corresponding chain on its purpose, it will be closed immediately. The new requirement will prevent third - party developers can access the multimedia library user and send data on what is included back to a server without the express permission of the user. This includes changes in the media library that could have been used for advertising or tracking.