pod 时，你可能会遇到
[!] The version of CocoaPods used to generate the lockfile (1.5.3) is higher than the version of the current executable (1.3.1). Incompatibility issues may arise.
image error
这是因为本地的cocoapods库版本较低，需要更新本地资源库
执行 pod repo update 命令，等待更新完成即可。
