Does Jフェス work on iPhone Duo?
Not yet. Jフェス's current version (33.1.0, 3 September 2026) came out before Apple's iPhone Duo tools, so on the inner screen it opens in an iPhone-size window with black bars. It works, just not full screen.
- On iPhone Duo
- Not yet
- Developer
- rockin'on holdings inc.
- Category
- Music
- Current version
- 33.1.0 · 3 September 2026
- App Store rating
- 4.6 out of 5 (7,519 ratings)
- Last checked
How we know
Its current version is older than Apple's iPhone Duo tools (5 October 2026): on the inner screen it opens in an iPhone-size window with black bars. See it on the App Store
History on iPhone Duo
- · Not yet (version 33.1.0)
Other Music apps on iPhone Duo
-
YouTube MusicGoogle · MusicUpdated, unconfirmedUpdated 25 October 2026 -
Multi Track Song Recorder ProDerrick Walker · MusicNot yetLast update 19 February 2019 -
iReal ProTechnimo LLC · MusicAdaptedRelease notes, version 2026.9 -
Cubase iC ProSteinberg Media Technologies GmbH · MusicNot yetLast update 10 April 2026 -
Deck-ManSquircle Apps LLP · MusicAdaptedApple's list, 22 October 2026 -
AnghamiAnghami · MusicNot yetLast update 1 October 2026 -
SpotifySpotify · MusicUpdated, unconfirmedUpdated 23 October 2026 -
iTablaProPrasad Upasani · MusicNot yetLast update 11 August 2025
All apps on iPhone Duo in the UAE →
Got an iPhone Duo? How does Jフェス look on the inner screen?
No owner report yet for version 33.1.0.
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Good to know
Does Jフェス work on iPhone Duo?
Not yet. Jフェス's current version (33.1.0, 3 September 2026) came out before Apple's iPhone Duo tools, so on the inner screen it opens in an iPhone-size window with black bars. It works, just not full screen.
Why do some apps have black bars on iPhone Duo?
Because they were built before Apple's iPhone Duo tools. On the inner screen, an app built for an older iOS opens in an iPhone-size window on a black background; one built for iOS 27.0 uses more of it but leaves some space blank; only apps built with the iOS 27.1 SDK, which developers have had since 5 October 2026, use the whole display.
When will Jフェス be adapted to iPhone Duo?
Only rockin'on holdings inc. knows. We check Jフェス on the App Store again within about 1 h: this page changes as soon as a new version says it supports iPhone Duo.
Do apps that aren't adapted still work on iPhone Duo?
Yes. Every iPhone app runs on iPhone Duo: one that isn't adapted just doesn't fill the inner screen until its developer updates it.
How we measure
Sources: Apple's list of apps adapted to iPhone Duo (22 October 2026) and each app's App Store record (version, release date, release notes, description). Apple doesn't say which tools an app was built with, so an app stays “Updated, unconfirmed” until its developer says more.