USB-Meter
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Platform Decision - iOS 15.md
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# Platform Decision: iOS 15 |
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Date: 2026-03-22 |
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## Decision |
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Minimum deployment target for the app becomes `iOS 15`. |
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This is the last iOS version supported by `iPhone 6s`, which remains a valid target device for this product: |
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- BLE communication is fully capable on this hardware. |
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- Live data acquisition, diagnostics, and logging are within its capabilities. |
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- Local history and long-term battery tracking are also realistic for the product goals. |
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## Product Goals |
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The application is intended to support: |
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- live data collection for device diagnostics |
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- real battery capacity measurement using USB meters |
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- long-term degradation tracking through historical data |
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- efficiency analysis for charging chains |
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- charger efficiency analysis |
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## Why We Are Leaving iOS 13 |
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`iOS 13` is too old for the current development direction: |
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- first-generation SwiftUI requires more workarounds and compatibility code |
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- maintenance and testing cost is higher |
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- newer Xcode / App Store tooling trends are centered around more recent deployment targets |
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Moving to `iOS 15` reduces risk without dropping `iPhone 6s`. |
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## Why We Are Not Moving to iOS 16 Yet |
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`iOS 16` would unlock APIs such as `NavigationStack` and `Swift Charts`, but it would also exclude `iPhone 6s`. |
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At this stage, preserving `iPhone 6s` support is considered more valuable than gaining those APIs. |
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## Charts Decision |
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Current conclusion: |
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- keep the in-house chart solution for live charts |
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- do not adopt `Swift Charts` for the live measurement view |
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- reconsider `Swift Charts` later only for historical reports and analysis screens |
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Reasoning: |
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- `Swift Charts` looks strong for reports and final analysis |
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- it does not appear ideal for high-frequency live updates |
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- zoom and pan would still require custom work |
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- the current in-house renderer gives better control for instrument-style live views |
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## Device Coverage Notes |
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Choosing `iOS 15` preserves `iPhone 6s` support. |
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There are also older iPads that remain on `iPadOS 15`. Apple security release notes for January 26, 2026 still list devices such as: |
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- `iPad Air 2` |
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- `iPad mini 4` |
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So this platform decision likely preserves some older iPad coverage as well. |
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## Revisit Trigger |
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We should revisit the minimum deployment target when one of the following becomes important: |
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- a strong need for `Swift Charts` |
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- a move toward `SwiftData` / more modern SwiftUI app architecture |
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- loss of business value in keeping `iPhone 6s` support |
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- support or distribution constraints imposed by newer Xcode / App Store requirements |
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## References |
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- Apple Xcode system requirements: https://developer.apple.com/xcode/system-requirements/ |
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- Apple upcoming App Store requirements: https://developer.apple.com/news/upcoming-requirements/ |
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- Apple App Store platform usage: https://developer.apple.com/support/app-store/ |
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- Apple security releases: https://support.apple.com/en-lamr/100100 |