Value for External Accessory of "Required background modes" key in iOS5

Question

I read iOS Programming Guide, and I found not only "audio, location, voip", but also "External Accessory & Newsstand apps" are allowed in background mode. documents are as following:

In iOS, only specific app types are allowed to run in the background:

• Apps that play audible content to the user while in the background, such as a music player app
• Apps that keep users informed of their location at all times, such as a navigation app
• Apps that supportVoice over Internet Protocol (VoIP)
• Newsstand apps that need to download and process new content
• Apps that receive regular updates from external accessories

However, I couldn't find the value for External Accessory in "Required background modes" key. Only I can choose is "App plays audio, App registers for location updates, App provides Voice over IP services".

Is it impossible to receive data from External Accessory when app is background mode ?

Thanks.

Answer 1

Values for the UIBackgroundModes array for iOS5 and iOS6

audio

location

voip

newsstand-content

external-accessory

bluetooth-central

bluetooth-peripheral (supported from iOS6)

Answer 2

Though I couldn't select from lists, I could type "external-accessory", and it worked well.