CycleOne

A privacy-first, sophisticated menstrual cycle & fertility tracker for iOS.

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Overview

CycleOne is a high-performance, open-source period tracker designed for users who value privacy above all else.

In an era of cloud-connected health apps, CycleOne takes a stand: Your health data is yours alone. Built with a strict "local-only" architecture, it provides professional-grade cycle prediction, symptom tracking, and historical analysis without ever requesting network access, requiring an account, or charging a subscription fee.

Core Features

Visual Preview

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Advanced Prediction Engine

• Period Projection: Intelligent estimations for start dates and duration based on historical averages.
• Ovulation Tracking: Automatic calculation of ovulation and fertile windows.
• Irregularity Alerts: Identifies significant cycle variances to help you remain aware of physiological shifts.

Holistic Logging

• Flow Intensity: Categorical tracking from spotting to heavy flow.
• Symptom Database: Track physical, emotional, and digestive indicators.
• Mood & Energy: Document biometric indicators with a streamlined, premium UI.
• Notes: Local-only annotations for detailed record-keeping.

Premium User Experience

• Native Calendar: Leveraging UICalendarView for a high-contrast, interactive experience.
• Dynamic Themes: 5 custom accent color themes (Rose, Lavender, Ocean, Sage, Sunset) to match your style.
• Smooth Animations: High-fidelity transitions and staggered animations for a premium app feel.
• Zero Emojis: A consistent, professional aesthetic using high-quality SF Symbols.

Localization

• In-app language switcher in Settings with runtime locale updates.
• Supported languages: English (en), Filipino/Tagalog (fil), Japanese (ja).
• Coverage guardrails: localization parity and source-key coverage tests in CycleOneTests/LocalizationCoverageTests.swift.
• Localized custom pages: Privacy Policy HTML is shipped per language resource bundle.
• Organized resources: language folders are grouped under CycleOne/LocalizationResources/ in source.
• Legend correctness: Calendar legend labels resolve localized values (not raw string keys).
• Round-trip stability: UI tests validate language switching Japanese -> English and verify localized legend text remains correct.

Note on folder structure:

• Source files are grouped in CycleOne/LocalizationResources for maintainability while preserving runtime localization behavior.

The Privacy Manifesto

CycleOne was built from the ground up to be safe:

• No Cloud Sync: Your data never leaves your device.
• No Accounts: No email, no password, no login required.
• No Analytics: Zero third-party tracking or telemetry.
• No Network Entitlements: The app doesn't even ask for internet permissions.
• Data Sovereignty: Export your entire history to CSV anytime.

Technical Specifications

Component	Technology
Language	Swift 5.9+
Framework	SwiftUI with MVVM Architecture
Logic	Proprietary CycleEngine (Pure Swift)
Persistence	Core Data (On-device SQLite)
Interface	Native UIKit/SwiftUI hybrid
Testing	XCTest (99 tests currently passing in the full suite: 90 unit + 9 UI)

Getting Started

Prerequisites

• macOS 14.0+
• Xcode 15.0+
• SwiftLint & SwiftFormat

Development Setup

1. Clone the repo:

   git clone https://github.com/VoxDroid/CycleOne.git

2. Install pre-commit hooks:

   brew install pre-commit
   pre-commit install

3. Open CycleOne.xcodeproj and build for the simulator.

Workflow Commands

We use a Makefile for CI/CD consistency:

• make check: Full verification suite (Lint, Format, Test, UI Test).
• make test: Execute the unit-test suite and produce TestResults.xcresult output.
• make test-ui: Execute UI tests only.

Localization Validation

DEST_ID=$(xcrun simctl list devices available | awk -F '[()]' '/iPhone/ {print $2; exit}')
if [ -z "$DEST_ID" ]; then
  echo "No available iPhone simulator found."
  exit 1
fi

xcodebuild test \
  -project CycleOne.xcodeproj \
  -scheme CycleOne-Unit \
  -destination "id=${DEST_ID}" \
  -parallel-testing-enabled NO \
  -only-testing:CycleOneTests/LocalizationCoverageTests \
  -only-testing:CycleOneTests/AppLanguageTests

Portable XCTest Command

DEST_ID=$(xcrun simctl list devices available | awk -F '[()]' '/iPhone/ {print $2; exit}')
if [ -z "$DEST_ID" ]; then
  echo "No available iPhone simulator found."
  exit 1
fi

xcodebuild test \
  -project CycleOne.xcodeproj \
  -scheme CycleOne-Unit \
  -destination "id=${DEST_ID}" \
  -parallel-testing-enabled NO \
  -only-testing:CycleOneTests

Coverage Snapshot

Latest merged local run (UnitCoverage.xcresult + UICoverage.xcresult, 2026-04-08):

• CycleOne.app: 10,893 / 10,893 lines (100.00%)
• CycleOneTests.xctest: 4,298 / 4,316 lines (99.58%)
• CycleOneUITests.xctest: 955 / 962 lines (99.27%)

Latest run counts:

• CycleOneTests.xctest: 182 tests, 0 failures.
• CycleOneUITests.xctest: 22 tests, 0 failures.

Validation commands executed for this snapshot:

• make check
• pre-commit run --all-files

Recent reliability/security improvements in this iteration:

• CSV export now escapes quotes, preserves commas safely, and mitigates spreadsheet formula injection (=, +, -, @ prefixes).
• Cycle rebuild now logs Core Data fetch/save failures instead of silently swallowing errors.
• Log saving now enforces the Core Data note-length limit (500 chars) to prevent save failures from oversized notes.

Contributing

We welcome contributions! Please see CONTRIBUTING.md for guidelines on how to get involved.

License

CycleOne is released under the GNU General Public License v3.0. See LICENSE for details.

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Designed and developed by VoxDroid.
© 2026 VoxDroid. All rights reserved.