After installing this plugin for iOS, you might get this error.
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Showing first 200 notices only
** BUILD FAILED **
I don't know why, but it seems the cordova CLI does not work correctly sometimes.
Open the project with Xcode (under the platforms/ios/***.xcodeproj),
then confirm the installed frameworks.
If less, try cordova remove plugin.google.maps and cordova add plugin.google.maps again couple of times.