@符号表示有有问题的文件的扩展属性。要验证应用到文件的扩展属性是：

The @ symbol indicates that there are extended attributes for the files in question. To verify the extended attributes applied to the files use:

ls -l@

您可能会发现（像我一样），有对文件的属性com.apple.quarantine可以与被删除：

You'll probably find (as I did) that there is a com.apple.quarantine attribute on the files which can be removed with:

xattr -dr com.apple.quarantine sdkFolder

在哪里sdkFolder与该文件夹的名称替换您提取SDK来。

Where sdkFolder should be replaced with the name of the folder you extracted the SDK to.