CocoaPods: point to a branch in pod spec
Please check the discussion here - Link
I think it is possible now as per the discussion but initially -
They suggested Tag instead of the branch as the problem with a branch vs a tag is that a branch does not specify a specific point in the history, whereas a tag does. This distinction is very important, as we need to guarantee that depending on a specific version of the library will result in using the same source every time. Technically it is possible to delete a tag and create it again pointing to a different commit, but this is less likely to happen.