| Field | Xcode 4.2 | Xcode 4.2.1 | Diff |
|---|---|---|---|
| Release type | stable | stable | same |
| Edition | - | - | same |
| Release date | 2011-10-12 | 2011-11-17 | different |
| Minimum macOS | 10.6.8 | 10.7 | different |
| Swift | unknown | unknown | same |
| iOS SDK | unknown | unknown | same |
| Build | 4C199 | 4D502 | different |
建议：如果你是生产环境主力开发，优先选择 stable 版本；如需验证新 SDK，再考虑 beta。