Does Topo Maps+ work on iPhone Duo?

Yes. Topo Maps+ is updated for iPhone Duo and uses the full inner display. Its latest version is built with the iOS 27.1 SDK and uses Apple’s iPhone Duo APIs.

Is Topo Maps+ letterboxed on iPhone Duo?

No. Topo Maps+ fills the inner display.

All apps

Topo Maps+

Name: Topo Maps+: Topographic Maps
Author: Glacier Peak Studios LLC

Glacier Peak Studios LLCMaps

View in the App Store

On iPhone Duo

Fits

Topo Maps+ fills the inner screen and adapts when you fold.

Its latest version is built with the iOS 27.1 SDK and uses Apple’s iPhone Duo APIs.[1]

How we know: From the app’s build
Checked on: Version 10.3.1
Build: iOS 27.1 SDK
uses Apple’s iPhone Duo APIs
Latest version: 10.3.1, Oct 21, 2026
Status updated: Oct 27, 2026

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Version history

Version 10.3.1Fits
iOS 27.1 SDK
Checked Oct 27, 2026

Sources

App Store build, version 10.3.1
Built with the iOS 27.1 SDK. Uses SwiftUI’s reservedRegions.
App Store: Topo Maps+ 10.3.1 release notes