Google maps autocomplete integration

Ionic Framework
3

I am currently using this topic

But I have this error :

[ng] : Compiled successfully.
[ng]     
[ng]     ERROR in src/app/add-event/add-event.page.ts:14:23 - error TS2503: Cannot find namespace 'google'.
[ng]     
[ng]     14   GoogleAutocomplete: google.maps.places.AutocompleteService;
[ng]                              ~~~~~~
[ng]     src/app/add-event/add-event.page.ts:22:35 - error TS2304: Cannot find name 'google'.
[ng]     
[ng]     22     this.GoogleAutocomplete = new google.maps.places.AutocompleteService();
[ng]                                          ~~~~~~