pod [!] Unable to satisfy the following requirements:

hi

pod show me : 
[!] Unable to satisfy the following requirements:
- `AFNetworking (~> 2.5.2)` required by `Podfile`
- `AFNetworking (= 2.5.2)` required by `Podfile.lock`
- `AFNetworking (~> 1.2.0)` required by `REActivityViewController (1.5.3)`

my pod file:
 pod 'AFNetworking', '~> 2.5.2'
 pod 'REActivityViewController', '~> 1.5.3'

I have to use  'AFNetworking' on version 2.5.2.
How can I do?
