iOS and Google Maps Premium Plan

To use Google maps you need to download the SDK if. You can download it using cocoapods or directly download it from the website and install it.

After installing it you have to request an API key and add it to the application by calling the SDK from the AppDelegate.

You can base yourself on the official guide that will be most useful to you: link

You must import the Google Maps SDK, either using cocoa pods or downloading it directly.

If you are going to use cocoapods, you have to add them in the Podfile file:

use_frameworks!
target 'NOMBRE_TARGET' do
pod 'GoogleMaps'
end

AppDelegate imports:

import GoogleMaps
import UIKit

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    let googleMapsApiKey = "MY_GOOGLE_IOS_API_KEY"

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        // Override point for customization after application launch.
        GMSServices.provideAPIKey(googleMapsApiKey)
        return true
     }
}

On iOS, you can not use the Client ID , only the Api Password .

"You can use an API key to authenticate requests to any of our APIs. To create your key, you must use the Google API Console project associated with your project ID.

Instead of an API key, you can use your customer ID to make requests to any of the APIs, to exception of the Google Places API, the Google Maps Geolocation API, Google Maps Roads API and the Mobile API (Android and iOS) . " Link