Get Device Token in iOS 8

Read the code in UIApplication.h.

You will know how to do that.

First:

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

add Code like this

#ifdef __IPHONE_8_0
  //Right, that is the point
    UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:(UIRemoteNotificationTypeBadge
|UIRemoteNotificationTypeSound
|UIRemoteNotificationTypeAlert) categories:nil];
    [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
#else
    //register to receive notifications
    UIRemoteNotificationType myTypes = UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeAlert | UIRemoteNotificationTypeSound;
    [[UIApplication sharedApplication] registerForRemoteNotificationTypes:myTypes];
#endif

if you not using both Xcode 5 and Xcode 6 ,try this code

if ([application respondsToSelector:@selector(registerUserNotificationSettings:)]) {
  UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:(UIRemoteNotificationTypeBadge
      |UIRemoteNotificationTypeSound
      |UIRemoteNotificationTypeAlert) categories:nil];
  [application registerUserNotificationSettings:settings];
} else {
  UIRemoteNotificationType myTypes = UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeAlert | UIRemoteNotificationTypeSound;
  [application registerForRemoteNotificationTypes:myTypes];
}

(Thanks for @zeiteisen @dmur 's remind)

---

Second:

Add this Function

#ifdef __IPHONE_8_0
- (void)application:(UIApplication *)application didRegisterUserNotificationSettings:(UIUserNotificationSettings *)notificationSettings
{
    //register to receive notifications
    [application registerForRemoteNotifications];
}

- (void)application:(UIApplication *)application handleActionWithIdentifier:(NSString *)identifier forRemoteNotification:(NSDictionary *)userInfo completionHandler:(void(^)())completionHandler
{
    //handle the actions
    if ([identifier isEqualToString:@"declineAction"]){
    }
    else if ([identifier isEqualToString:@"answerAction"]){
    }
}
#endif

And your can get the deviceToken in

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken

if it still not work , use this function and NSLog the error

-(void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error

Appending a small validation to @Madao's response in case you are having crashes on older iOS versions:

#ifdef __IPHONE_8_0
if(NSFoundationVersionNumber > NSFoundationVersionNumber_iOS_7_1) {
    UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:(UIUserNotificationTypeBadge|UIUserNotificationTypeSound|UIUserNotificationTypeAlert) categories:nil];
    [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
}
#endif

UIRemoteNotificationType myTypes = UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeAlert | UIRemoteNotificationTypeSound |     UIRemoteNotificationTypeNewsstandContentAvailability;
[[UIApplication sharedApplication] registerForRemoteNotificationTypes:myTypes];

What the __IPHONE_8_0 macro does is just allowing you to compile in older versions of xCode/iOS, you don't get compilation errors or warnings, but running the code on devices with iOS 7 or lower will cause a crash.