Before you can code sign your app, you create your development certificate and later, a distribution certificate to upload your app to iTunes Connect. You can create all the types of certificates and signing identities you need using Xcode. Xcode creates, downloads, and installs your signing identities for you.
在你代码签名你的App之前，你要生成开发证书，然后，生成一个发布证书，将你的App上传到iTunes Connect。你可以用Xcode生成你需要的所有类型的证书和签名标识。Xcode生成、下载和安装你需要的签名标识。
All team members can create their own development certificate. Only a team agent or admin can create a distribution certificate. Only a team agent can create a Developer ID certificate. If you have an organization membership, read Managing Your Developer Account Team for a description of team roles and tasks that team agents perform on behalf of team members.
所有的团队成员都可以生成他们自己的开发证书。只有一个团队的代理或者管理员可以产生发布证书。只有团队代理可以产生一个开发ID证书。如果你有机构关系，读一读 管理你的开发账号团队，是 一个对团队代理可以代表团队角色和任务的描述。
Xcode creates your development certificate for you when you need it. For example, when you assign your project to a team or create the team provisioning profile, as described in Configuring Identity and Team Settings, Xcode creates your development certificate and adds it to the team provisioning profile. Because of this, you typically create distribution certificates using the Xcode Preferences window.
Xcode可以生成你需要的开发者证书。比如：当你对你团队的项目进行签名或者生成团队配置文件时，如 确认标识和团队设置 里面描述的，Xcode生成你的开发 证书并且将它加到团队配置文件里面。正因为如此，你可以使用Xcode的偏好设置窗口去生成分发证书。
如何生成呢？
在Xcode的Preference里面，点击账号，选中开发者公司或者个人的名字，ViewDetails，然后点击create，就会生成自己相对应的签名标识。如果不能生成，说明你没有这个权限。