执行pod lib lint --allow-warnings命令错误解决方案
错误提示1：
WARN | [iOS] swift: The validator used Swift 3.2 by default because no Swift version was specified. To specify a Swift version during validation, add the `swift_version` attribute in your podspec. Note that usage of the `--swift-version` parameter or a `.swift-version` file is now deprecated.
解决方案：
这个主要说明的是用pod lib create创建的库的开发语言版本与xcode的版本不匹配，解决方案是，在PodPack.podspec中添加开发语言版本描述
s.swift_version = '3.3'
错误提示2：
xcrun: error: unable to find utility "simctl", not a developer tool or in PATH) during validation.
解决方案：
如下操作
错误提示： - ERROR | xcodebuild: Returned an unsuccessful exit code. You can use `--verbose` for more information.
解决方案是缺少必要的依赖
错误提示：- ERROR | [iOS] swift: Swift support uses dynamic frameworks and is therefore only supported on iOS > 8
s.platform = :ios, "9.0"
