How to add Framework containing pods into another project

If you're using multiple Xcode Projects in a single Workspace, you should use pod targets like this:

platform :ios, '9.0'
inhibit_all_warnings!
use_frameworks!

target "MyApp" do
  xcodeproj 'MyApp'
  pod 'MQTTKit'

  target "SampleApp" do
    xcodeproj 'SampleApp'
    inherit! :search_paths
    pod 'MQTTKit'
  end
end

To learn more, refer to Cocoapods Podfile Syntax Reference