# PDF File Protector vs 投屏助手

The clearest difference is price: 投屏助手 at Free against PDF File Protector's $19.99. 投屏助手 also leads on iOS requirement (13.0 vs 16.6). On update cadence, ads, in-app purchases and device support there is nothing between them.

投屏助手 is free to download; PDF File Protector costs $19.99 up front. PDF File Protector sells 1 one-off in-app purchase and 投屏助手 sells 6 in-app purchases, starting at $0.99 per 7 days. Whichever you choose, the download price is not the number that matters.

PDF File Protector ships an update every 2 months, 投屏助手 every 4 months. The most recent releases landed on September 26, 2026 and September 7, 2026 respectively.

## The numbers

| Metric | PDF File Protector | 投屏助手 |
| --- | --- | --- |
| Price | $19.99 | **Free** |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 4 months |
| Size | 7 MB | 29 MB |
| Requires iOS | 16.6 | **13.0** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [乐祥 胡](https://appshunter.io/developer/1572365721) | [伊凡 马](https://appshunter.io/developer/1804172759) |

## What reviewers say

### PDF File Protector

[App page](https://appshunter.io/ios/app/pdf-file-protector/id6738285744)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| pdf签名内购 | $9.99 | one-time |


### 投屏助手

[App page](https://appshunter.io/ios/app/and/id6739403795)

**Features:** macOS Compatibility

**In-app purchases (6)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 鸣思投屏助手:周度高级权限服务订阅 | $0.99 | per 7 days |
| 鸣思投屏助手:季度高级权限服务订阅 | $3.99 | per 3 months |
| 鸣思投屏助手:周度高级权限订阅 | $3.99 | per 7 days |
| 投屏助手：高级服务权限周度订阅 | $4.99 | per 7 days |
| 鸣思投屏助手:季度高级权限订阅 | $24.99 | per 3 months |
| 投屏助手：高级服务权限季度订阅 | $29.99 | per 3 months |


## Frequently asked questions

### Is PDF File Protector free?

PDF File Protector costs $19.99, and also offers in-app purchases.

### Is 投屏助手 free?

投屏助手 is free to download, with in-app purchases available.

### Do PDF File Protector or 投屏助手 have ads?

Neither PDF File Protector nor 投屏助手 shows ads.

### Which is updated more often, PDF File Protector or 投屏助手?

PDF File Protector ships an update every 2 months, and 投屏助手 every 4 months. Most recently, PDF File Protector was updated on September 26, 2026 and 投屏助手 on September 7, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*