Unable to install via CocoaPods

[richardtop]

I'm unable to install the library using CocoaPods, here is the command output:

Richards-MacBook-Pro:Proto richard$ pod install
Analyzing dependencies
[!] The platform of the target `Proto` (iOS 11) is not compatible with `GradientView (2.3.2)`, which does not support `ios`.

[!] Automatically assigning platform `ios` with version `11` on target `Proto` because no platform was specified. Please specify a platform for this target in your Podfile. See `https://guides.cocoapods.org/syntax/podfile.html#platform`.