Create a Connected App for Apple iOS

From Setup, click Create | Apps.
In the Connected Apps section, click either Edit next to an existing connected app, or New to create a new connected app.
If you’re creating a new connected app:
1. Enter a unique name for your connected app. The API name field is auto-filled.
2. Optionally, fill in other fields, such as a description for your connected app.
3. Enter a contact email address.
4. In the OAuth Settings section, select Enable OAuth Settings.
5. Enter a callback URL.
6. Select OAuth scopes. At a minimum, select Access and manage your data (api) and Perform requests on your behalf at any time (refresh_token).
Under Mobile App Settings, select Push Messaging Enabled.
For Supported Push Platform, select Apple.
When you select the Supported Push Platform option, the dialog expands to show additional settings.
Select the Apple environment that is valid for your APNS push notifications certificate.
For Certificate, select the .p12 certificate file that you received from APNS when you registered your app for push notifications (for example, appkey.p12).
Enter the password for your .p12 certificate file.

Salesforce Mobile Push Notifications Implementation Guide