None of these worked for me. I have pod version 1.5.3 and the correct method was to remove the pods that were not longer needed from the Podfile and then run:
pod update
This updates your Podfile.lock file from your Podfile, removes libraries that have been removed and updates all of your libraries.
Remove the library from your Podfile
Run pod install
on the terminal
Remove lib from Podfile, then pod install
again.
Remove pod name from Podfile
then
Open Terminal, set project folder path and
Run pod update
command.
NOTE: pod update
will update all the libraries to the latest version and will also remove those libraries whose name have been removed from podfile.
Source: Stackoverflow.com