objective c - Ask for Permission for Local Notifications in iOS 8, but still have the App Support iOS 7

Question

I have an app which uses local notifications. In iOS 7 everything works fine, but in iOS 8 the app needs to ask for user permission to display notifications. To ask for permission in iOS 8 I'm using:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

{
  [application registerUserNotificationSettings:[UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeAlert|UIUserNotificationTypeBadge|UIUserNotificationTypeSound categories:nil]];
}

It works fine in Xcode 6 and in iOS 8. When I open the same project in Xcode 5, the error is a Semantic Issue. "Use of undeclared identifier 'UIUserNotificationSettings'."

How can I get the app to work with iOS 7 & 8, and have the notifications work properly on both versions.

Answer 1

The following answer makes a few assumptions:

1. The app must build properly with a Base SDK of iOS 8 when using Xcode 6 and it must build properly with a Base SDK of iOS 7 when using Xcode 5.
2. The app must support a Deployment Target of iOS 7 (or earlier) regardless of the Base SDK and Xcode version.

Code:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // None of the code should even be compiled unless the Base SDK is iOS 8.0 or later
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000
    // The following line must only run under iOS 8. This runtime check prevents
    // it from running if it doesn't exist (such as running under iOS 7 or earlier).
    if ([application respondsToSelector:@selector(registerUserNotificationSettings:)]) {
        [application registerUserNotificationSettings:[UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeAlert|UIUserNotificationTypeBadge|UIUserNotificationTypeSound categories:nil]];
    }
#endif
}

All of this is covered in the Apple SDK Compatibility Guide.