Privacy Policy
Danci Danyu ("we" or "the App") takes your privacy seriously. This policy explains what information we collect, use, and store when you use the Danci Danyu iOS app, and the rights you have. If you do not agree with any part of this policy, please do not install or use the App.
1. What we do not collect
Danci Danyu's core learning features run locally on your device. We do not:
- collect personally identifiable information (name, phone number, email, national ID, etc.);
- collect the advertising identifier (IDFA), nor do we show an ATT (App Tracking Transparency) prompt;
- collect your location, contacts, photos, or calendar;
- require you to register an account or sign in;
- track you across other apps.
To understand overall app usage, monitor crashes and performance, and measure the effectiveness of our promotions, we collect the device's vendor identifier (IDFV), device and usage information, and performance/crash diagnostics. See "4. Analytics, performance monitoring, and ad attribution" below. This collection begins only after you agree to this Privacy Policy.
2. What we store locally
To provide core features, the App stores the following on your device only (inside the app sandbox):
| Data | Where it is stored | Purpose |
|---|---|---|
| Learning progress (completed word sets and modes) | UserDefaults | Show completion badges and the recent-practice entry |
| Spaced-repetition state (each word's next review date, proficiency, etc.) | Application Support sandbox | Run the SM-2 review algorithm |
| Daily review activity counts | Application Support sandbox | Streaks and the 12-week heatmap |
| App preferences (daily reminder time, AI enabled, etc.) | UserDefaults | Settings panel |
| Favorited dictionary words | UserDefaults | "Favorites" and the favorites practice pool |
| Dictionary search history (last 20) | UserDefaults | Quickly reuse queries |
| User-created word sets | Application Support sandbox | Your personal word-set library |
| DeepSeek API key (if you provide one) | iOS Keychain (encrypted) | BYOK — use AI without a subscription |
This learning data is stored on your device only. It is not uploaded to our servers and is not synced to other devices. (The device identifiers, usage information, and diagnostics used for analytics, performance monitoring, and ad attribution are an exception — see Section 4.)
3. AI Learning Assistant and third-party services
When you enable AI in Settings and use the features below, the App sends a small amount of data to the third-party large-language-model service DeepSeek (Hangzhou DeepSeek Artificial Intelligence Basic Technology Research Co., Ltd.) to generate content:
- Smart word breakdown: sends the English word you looked up and its locally stored Chinese definition;
- Learning diagnosis report: sends an aggregated summary of your local learning data (e.g., a list of weak-word IDs and weak roots), without full review history or timestamps;
- Custom word-set generation: sends the topic description you type (e.g., "20 common airport words");
- AI study chat: sends the message you type plus a few recent messages for context.
We do not send your account information, device identifiers, email, phone number, IP-based location, or any other information that could identify you.
DeepSeek's processing of data is governed by its own privacy policy: https://platform.deepseek.com/.
If you prefer that no data leaves your device, you can turn off the AI toggle under "Me → Settings → AI". Once off, no AI feature makes any network request.
4. Analytics, performance monitoring, and ad attribution
Consent note: all third-party SDKs below initialize and begin collecting data only after you launch the App for the first time and agree to this Privacy Policy. Before you agree, they do not run and collect nothing.
4.1 Usage analytics and performance monitoring (Umeng+)
To understand overall app usage, improve features, and diagnose crashes and hangs, the App integrates the Umeng+ Analytics SDK (U-App) and Performance Monitoring SDK (U-APM) (provided by Umeng Tongxin (Beijing) Technology Co., Ltd.). They collect anonymous usage and diagnostic data so we can learn which features are popular and where the App runs into problems. Specifically:
- Data collected includes: device information (model, OS version, screen, network type, carrier, language and time zone), a device identifier (derived from IDFV, not IDFA), usage data (launch counts, session duration, page and custom events, app version and channel), and performance/crash diagnostics (crash and hang stacks, launch time, memory, etc.);
- we do not enable Umeng's network-request monitoring module, so we do not record the content of your network requests;
- we do not collect IDFA and do not track you across apps;
- this data is sent by the SDK directly to Umeng's servers, used only for analytics and quality improvement, and not used to identify you personally.
4.2 Ad attribution (Ocean Engine)
To measure the effectiveness of promotions we run on third-party platforms, the App integrates the Ocean Engine Conversion SDK (provided by Beijing Ocean Engine Network Technology Co., Ltd. / ByteDance). The SDK is used for ad install attribution — determining whether an install came from a particular ad click, so we can evaluate campaign performance.
In this process:
- we do not collect the advertising identifier (IDFA), and we do not show an ATT (App Tracking Transparency) prompt;
- attribution relies on the device's IDFV (vendor identifier, consistent only across apps from the same vendor and reset on reinstall) and a click identifier (CLICKID) present only when you open the App via an ad link;
- we do not link this information with any data that could personally identify you.
Data flow: App → (HTTPS) our server → Ocean Engine attribution API. When you complete an in-app purchase, we also send the transaction amount (without your Apple ID, payment credentials, or any other detail) over the same path to optimize ad delivery.
Third-party SDKs integrated in this App:
| SDK | Provider | Purpose | Data collected | Privacy policy |
|---|---|---|---|---|
| Umeng+ Analytics & Performance SDK (U-App / U-APM) | Umeng Tongxin (Beijing) Technology Co., Ltd. (Umeng+) | Usage analytics / performance & crash monitoring | Device information, device identifier (derived from IDFV, not IDFA), app usage data, performance and crash diagnostics | View |
| Ocean Engine Conversion SDK | Beijing Ocean Engine Network Technology Co., Ltd. (ByteDance) | Ad install attribution / conversion measurement | Device identifier (IDFV), click identifier (CLICKID), basic network and device information | View |
5. Subscriptions and payments
The App offers a monthly subscription through Apple's App Store in-app purchase system. Payment is handled by Apple; we never see your credit card, Apple ID, or similar details. Subscription status is verified locally through StoreKit's currentEntitlements API, and no credentials are uploaded.
6. Children's privacy
The App is intended for users aged 4 and up and does not knowingly collect personal information from children under 14. If you believe a child's information has been collected in a way that violates this policy, please contact us to have it deleted.
7. Your rights
- Access: all local data is visible to you through the app's interface.
- Delete: "Me → Settings → Data → Clear learning records / Clear favorites and history" wipes it instantly.
- Stop AI network calls: turn off "Settings → Enable AI".
- Uninstall: uninstalling the App deletes all local data, leaving nothing behind.
8. Changes to this policy
If we make material changes to this policy, we will notify you before they take effect through an in-app notice or a prominent notice on this page. Continued use of the App constitutes acceptance of the updated policy.
9. Contact us
For questions, suggestions, or to exercise your rights, contact us via:
- Email: b@guannian.com
- WeChat: eclectically