Specs satisfying the app_review (from .symlinks/plugins/app_review/ios) dependency were found, but they required a higher minimum deployment target.

[suztomo]

~/Documents/hitomemo/ios $ pod install                                                        git[branch:i113]
Analyzing dependencies
[!] CocoaPods could not find compatible versions for pod "app_review":
  In Podfile:
    app_review (from `.symlinks/plugins/app_review/ios`)

Specs satisfying the `app_review (from `.symlinks/plugins/app_review/ios`)` dependency were found, but they required a higher minimum deployment target.

[!] Automatically assigning platform `iOS` with version `8.0` on target `Runner` because no platform was specified. Please specify a platform for this target in your Podfile. See `https://guides.cocoapods.org/syntax/podfile.html#platform`.

This is solved by updating the iOS Deployment Target value in Xcode:

[suztomo]

Closing this issue. Hope this issue helps others in future.