Push notifications registration: iOS7 & iOS8

WMLPushNotificationRegistrationService.h

#import <Foundation/Foundation.h>

@interface WMLPushNotificationRegistrationService : NSObject

+ (instancetype)sharedInstance;

@property (nonatomic, readonly, getter=isRegisteredForPushNotifications) BOOL registeredForPushNotifications;

/**
 *  Must be called every app startup, once got user's permission to send push notificaitons
 */
- (void)registerForPushNotifications;

/**
 *  Updates APN token. This method perform work only if @c isRegisteredForPushNotifications is @c YES.
 */
- (void)requestUpdatedTokenForPushNotifications;

@end

WMLPushNotificationRegistrationService.m

#import "WMLPushNotificationRegistrationService.h"

#import "WMLPushNotificationRegistrationService_iOS7.h"
#import "WMLPushNotificationRegistrationService_iOS8.h"

@implementation WMLPushNotificationRegistrationService

+ (instancetype)sharedInstance {
    // your IOC, static instance etc
    return [JSObjection defaultInjector][ self ]; 
}

- (instancetype)init {
    if (![self isMemberOfClass:[WMLPushNotificationRegistrationService class]]) {
        return [super init];
    }
    
    NSOperatingSystemVersion version = {8,0,0};
    // I backported this method to iOS7, but you can also use -[UIDevice systemVersion]
    if ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:version]) {
        return [[WMLPushNotificationRegistrationService_iOS8 alloc] init];
    }
    return [[WMLPushNotificationRegistrationService_iOS7 alloc] init];
}

- (void)registerForPushNotifications {
    // no-op
}

- (void)requestUpdatedTokenForPushNotifications {
    if (self.isRegisteredForPushNotifications) {
        [self registerForPushNotifications];
    }
}

@end

WMLPushNotificationRegistrationService_iOS7.m

#import "WMLPushNotificationRegistrationService_iOS7.h"

@implementation WMLPushNotificationRegistrationService_iOS7

- (BOOL)isRegisteredForPushNotifications {
    UIRemoteNotificationType registeredTypes = [[UIApplication sharedApplication] enabledRemoteNotificationTypes];
    return ((registeredTypes & UIRemoteNotificationTypeBadge) |
            (registeredTypes & UIRemoteNotificationTypeSound) |
            (registeredTypes & UIRemoteNotificationTypeAlert));
}

- (void)registerForPushNotifications {
    [[UIApplication sharedApplication] registerForRemoteNotificationTypes:UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeAlert | UIRemoteNotificationTypeSound];
}

@end

WMLPushNotificationRegistrationService_iOS8.m

#import "WMLPushNotificationRegistrationService_iOS8.h"

@implementation WMLPushNotificationRegistrationService_iOS8

- (BOOL)isRegisteredForPushNotifications {
    if (![[UIApplication sharedApplication] isRegisteredForRemoteNotifications]) {
        return NO;
    }
    UIUserNotificationSettings *settings = [[UIApplication sharedApplication] currentUserNotificationSettings];
    return ((settings.types & UIUserNotificationTypeAlert) |
            (settings.types & UIUserNotificationTypeBadge) |
            (settings.types & UIUserNotificationTypeSound));
}

- (void)registerForPushNotifications {
    UIUserNotificationType types = UIUserNotificationTypeAlert | UIUserNotificationTypeBadge | UIUserNotificationTypeSound;
    UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:types categories:nil];
    [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
    [[UIApplication sharedApplication] registerForRemoteNotifications];
}

@end