环境：
os：Mac os Mojave10.14.4
Cocospod：1.6.0beta
操作：
代码语言：javascript复制pod spec lint错误：
代码语言：javascript复制ERROR | [iOS] unknown: Encountered an unknown error (Could not find a `ios` simulator (valid values: com.apple.coresimulator.simruntime.ios-12-1, com.apple.coresimulator.simruntime.ios-12-2, com.apple.coresimulator.simruntime.tvos-12-2, com.apple.coresimulator.simruntime.watchos-5-2). Ensure that Xcode -> Window -> Devices has at least one `ios` simulator listed or otherwise add one.) during validation.资料分析（作者issue）：
很多人发生了这个问题。
https://github.com/CocoaPods/fourflusher/issues/18
https://github.com/CocoaPods/CocoaPods/issues/8458
解决办法：
1.升级Cocospod
2.更新fourflusher 2.2.0
本文更新到1.6.1解决，更新操作传送门
