# Double dummy problems vs 围棋之书

The clearest difference is ads: 围棋之书 at none against Double dummy problems's shown. Double dummy problems's advantage is iOS requirement (14.1 vs 16.6). On price, update cadence, in-app purchases and device support there is nothing between them.

Both are free to download. Double dummy problems sells 1 one-off in-app purchase and 围棋之书 sells 3 in-app purchases, starting at $2.99 per month. Whichever you choose, the download price is not the number that matters.

Double dummy problems ships an update every 3 weeks, 围棋之书 monthly. The most recent releases landed on September 9, 2026 and September 7, 2026 respectively.

## The numbers

| Metric | Double dummy problems | 围棋之书 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/id1644286562/reviews)** |
| Number of ratings | — | **1** |
| Positive reviews | — | 71.4% of reviews |
| In-app purchases | Yes | Yes |
| Ads | Yes | **No** |
| Update frequency | **Every 3 weeks** | Monthly |
| Size | 27 MB | 72 MB |
| Requires iOS | **14.1** | 16.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [丽娜 夏](https://appshunter.io/developer/1084968330) | [文艺 邓](https://appshunter.io/developer/1644286564) |

## What reviewers say

### Double dummy problems

[App page](https://appshunter.io/ios/app/double-dummy-problems/id1013055806)

**Features:** Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| You will pay to remove ads. | $1.99 | one-time |


### 围棋之书

[App page](https://appshunter.io/ios/app/id1644286562)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 连续包月 | $2.99 | per month |
| 连续包年 | $29.99 | per year |
| 永久会员 | $24.99 | one-time |


## Frequently asked questions

### Is Double dummy problems free?

Double dummy problems is free to download, with in-app purchases available.

### Is 围棋之书 free?

围棋之书 is free to download, with in-app purchases available.

### Do Double dummy problems or 围棋之书 have ads?

Double dummy problems shows ads; 围棋之书 does not.

### Which is updated more often, Double dummy problems or 围棋之书?

Double dummy problems ships an update every 3 weeks, and 围棋之书 monthly. Most recently, Double dummy problems was updated on September 9, 2026 and 围棋之书 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.*