You want to add pod 'MMUMOpenIM', '~> 0.0' similar to the following to your Podfile:
target 'MyApp' do
pod 'MMUMOpenIM', '~> 0.0'
end
Then run a pod install inside your terminal, or from CocoaPods.app.
Alternatively to give it a test run, run the command:
pod try MMUMOpenIM