How to properly use CFNotificationCenterAddObserver in Swift for iOS

Question

Pulling my hair out getting CFNotificationCenterAddObserver to work in Swift.

        CFNotificationCenterAddObserver(CFNotificationCenterGetDa         


        

Answer 1

I had some issues with DarwinNotifications, you can try using this wrapper class just include header file in your bridging file. And you can use it in swift.

DarwinNotificationsManager.h :

#import 

#ifndef DarwinNotifications_h
#define DarwinNotifications_h

@interface DarwinNotificationsManager : NSObject

@property (strong, nonatomic) id someProperty;

+ (instancetype)sharedInstance;

- (void)registerForNotificationName:(NSString *)name callback:(void (^)(void))callback;
- (void)postNotificationWithName:(NSString *)name;

@end

#endif

DarwinNotificationsManager.m :

#import 
#import "DarwinNotificationsManager.h"


@implementation DarwinNotificationsManager {
    NSMutableDictionary * handlers;
}

+ (instancetype)sharedInstance {
    static id instance = NULL;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[self alloc] init];
    });
    return instance;
}

- (instancetype)init {
    self = [super init];
    if (self) {
        handlers = [NSMutableDictionary dictionary];
    }
    return self;
}

- (void)registerForNotificationName:(NSString *)name callback:(void (^)(void))callback {
    handlers[name] = callback;
    CFNotificationCenterRef center = CFNotificationCenterGetDarwinNotifyCenter();
    CFNotificationCenterAddObserver(center, (__bridge const void *)(self), defaultNotificationCallback, (__bridge CFStringRef)name, NULL, CFNotificationSuspensionBehaviorDeliverImmediately);
}

- (void)postNotificationWithName:(NSString *)name {
    CFNotificationCenterRef center = CFNotificationCenterGetDarwinNotifyCenter();
    CFNotificationCenterPostNotification(center, (__bridge CFStringRef)name, NULL, NULL, YES);
}

- (void)notificationCallbackReceivedWithName:(NSString *)name {
    void (^callback)(void) = handlers[name];
    callback();
}

void defaultNotificationCallback (CFNotificationCenterRef center,
                 void *observer,
                 CFStringRef name,
                 const void *object,
                 CFDictionaryRef userInfo)
{
    NSLog(@"name: %@", name);
    NSLog(@"userinfo: %@", userInfo);

    NSString *identifier = (__bridge NSString *)name;
    [[DarwinNotificationsManager sharedInstance] notificationCallbackReceivedWithName:identifier];
}


- (void)dealloc {
    CFNotificationCenterRef center = CFNotificationCenterGetDarwinNotifyCenter();
    CFNotificationCenterRemoveEveryObserver(center, (__bridge const void *)(self));
}


@end

In swift you can use it like this :

let darwinNotificationCenter = DarwinNotificationsManager.sharedInstance()
darwinNotificationCenter.registerForNotificationName("YourNotificationName"){
            //code to execute on notification
}