Exception on API Key of Google Maps API for iOS

Problem finally solved, the reason is that I initialize a fields using Google Maps library in the one model class and it will be created before the app run. So this error happens. When I moved this variable into the method, problem solved. Following is the code that causes error:

class PlaceManager {
    let placeClient = GMSPlacesClient()
    ...
    func getSuggestions(queryString:String) -> [String]{
        ...
    }
}

After

class PlaceManager {
    func getSuggestions(queryString:String) -> [String]{
        let placeClient = GMSPlacesClient()
        ...
    }
}

Instead of didFinishLaunchingWithOptions, move the call to willFinishLaunchingWithOptions. This method is called after state restoration has occurred but before your app’s window and other UI have been presented. (Which in your case might be a UI that consumes Google Map API)

func application(application: UIApplication, willFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
GMSServices.provideAPIKey("***********************")

    return true
}

I just had the same problem. I created a GMSMapView object and it was initialized before maybe the api key could be read. So I moved it inside the viewDidLoad method and problem solved.

Before :

class ViewController: ..... {

let mapView = GMSMapView()

After :

class ViewController: ..... {

var mapView : GMSMapView?

override viewDidLoad(){
    mapView = GMSMapView()

In your appDelegate.m at didFinishLaunchingWithOptions this add these GMSService line with api key for me it worked.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  [GMSServices provideAPIKey:@"**************"];
  [FIRApp configure];
}

and add this import at the top

#import <GoogleMaps/GoogleMaps.h>