I was looking over the Reachability sample project on developer.apple.com and found that it was a large project just to verify you had network connectivity.
First part of the question is "What is the minimum code required to find out if the device can reach a 3G or wifi network?"
And next should this be done inside the appDelegate (on start) or inside the first View Controller that is launched?
Thank you in advance
It's not large, it really does what you want. If it is too big for you, you can extract what you need only like reachabilityForLocalWiFi. But I'm afraid that it will not be much smaller.
Yes, you can use reachability in your application delegate or inside the first view controller.
Reachability notification registration ...
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(networkReachabilityDidChange:)
name:kReachabilityChangedNotification
object:nil];
__reachability = [[Reachability reachabilityWithHostName:#"www.google.com"] retain];
[__reachability startNotifier];
... callback method example ...
- (void)networkReachabilityDidChange:(NSNotification *)notification {
Reachability *reachability = ( Reachability * )[notification object];
if ( reachability.currentReachabilityStatus != NotReachable ) {
// Network is available, ie. www.google.com
} else {
// Network is not available, ie. www.google.com
}
}
... do not forget to stop notifications, remove observer and release rechability object.
Related
I'm working on a AUv3 host app, and I want the users to be notified when a loaded audio unit crashes (gets invalidated) for some reason. I looked at Apple's documentations about AUAudioUnit, but couldn't find any information about how to detect an invalidation of an audio unit (AUv3) from the host app.
Does anyone know how to do this?
Thanks
when setting up your AudioEngine you can observe kAudioComponentInstanceInvalidationNotification to figure out if its audio component instance was invalidated later on.
[[NSNotificationCenter defaultCenter] addObserverForName:kAudioComponentInstanceInvalidationNotification object:nil queue:nil usingBlock:^(NSNotification *note) {
AUAudioUnit *auUnit = (AUAudioUnit *)note.object;
NSValue *val = note.userInfo[#"audioUnit"];
AudioUnit auAddress = (AudioUnit)val.pointerValue;
NSLog(#"AudioComponent Invalidation of Unit:%# with Address:%p", auUnit, auAddress);
}];
keep in mind that you may have got the notification but the component ended up in a deadlock. So when trying to recover from that you may have to turn down the whole host app.
I'd like to get notified when a certain application triggers an event. I'm not an Objective-C developer nor do I know the OS X APIs—so I hope this question is not too basic.
My goal is to write the meta info of the currently playing song to a log file. For iTunes, I got this working with the following Objective-C line:
[[NSDistributedNotificationCenter defaultCenter]
addObserver: myObserver selector: #selector(observeNotification:)
name: #"com.apple.iTunes.playerInfo" object:nil];
However, I also need this for AirServer (which is an software AirPlay receiver). Unfortunately, the following doesn't work—the observer never gets called:
[[NSDistributedNotificationCenter defaultCenter]
addObserver: myObserver selector: #selector(observeNotification:)
name: #"com.pratikkumar.airserver-mac" object:nil];
So apparently, AirServer does not send these type of notifications. However, there's a notification in the Notification Center when a new song starts playing.
My next step would be to periodically check for new notifications in the OS X Notification Center (as described here: https://stackoverflow.com/a/25930769/1387396). This is not too clean though—so my questions is: is there another option in this particular case?
Catalina silently changed the addObserver behavior - you can no longer use a nil value for the name to observe all notifications - you have to pass in a name. This makes discovery of event names more difficult.
Firstly, you have to understand that while the NSDistributedNotificationCenter has the word Notification in it; it's not related. From the About Local Notifications and Remote Notifications, it does state:
Note: Remote notifications and local notifications are not related to broadcast notifications (NSNotificationCenter) or key-value observing notifications.
So, at that point, I'm going to answer from the perspective of NSDistributedNotificationCenter, and not about Remote/Local notifications - you already have a potential solution in the answer you linked for observing the DB file that contains a record of the notifications in that way.
This example code will not work on Catalina (10.15) because of API behavior changes
The first thing you need to do is listen for the correct notification. Creating a simple application that listens for all events; e.g. using:
NSDistributedNotificationCenter *center = [NSDistributedNotificationCenter defaultCenter];
[center addObserver:self
selector:#selector(notificationEvent:)
name:nil
object:nil];
-(void)notificationEvent:(NSNotification *)notif {
NSLog(#"%#", notif);
}
It indicates that the notifications are:
__CFNotification 0x6100000464b0 {name = com.airserverapp.AudioDidStart; object = com.pratikkumar.airserver-mac; userInfo = {
ip = "2002:d55e:dbb2:1:10e0:1bfb:4e81:b481";
remote = YES;
}}
__CFNotification 0x618000042790 {name = com.airserverapp.AudioDidStop; object = com.pratikkumar.airserver-mac; userInfo = {
ip = "2002:d55e:dbb2:1:10e0:1bfb:4e81:b481";
remote = YES;
}}
This indicates that the name parameter in the addObserver call should be com.airserverapp.AudioDidStart and com.airserverapp.AudioDidStop.
You can use code like that to determine all notifications, which will allow you to add the relevant observers when you want the particular observer. This is probably the easiest way to observe notifications of this type.
I am trying to implement a OS X (10.10) client for the real time bitcoin exchange rate from bitstamp.com. They offer a great api, unfortunately I can't get the websocket api (https://www.bitstamp.net/websocket/) to work in an OS X Objective C app.
Everyone is pointing me to the libPusher Github project (https://github.com/lukeredpath/libPusher) but I tried literally everything I can think of, I can't get it to receive any pushes on 10.10.
Following the wiki page I downloaded the pre-compiled static library and dragged all files into my projects (I also made sure the "copy" checkbox was checked) and my sample applications compiles. Unfortunately, I never see either the "event through block" or "event through delegate" on the console. However I know that trades happened in the mean time, so that can't be the issue. Any ideas?
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
// Insert code here to initialize your application
PTPusher* client = [PTPusher pusherWithKey:#"de504dc5763aeef9ff52" delegate:self encrypted:YES];
[client connect];
PTPusherChannel *channel = [client subscribeToChannelNamed:#"live_trades"];
[channel bindToEventNamed:#"trade" handleWithBlock:^(PTPusherEvent *channelEvent) {
// channelEvent.data is a NSDictionary of the JSON object received
NSLog(#"event through block"); // <-- never called
}];
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(didReceiveEventNotification:)
name:PTPusherEventReceivedNotification
object:client];
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(didReceiveChannelEventNotification:)
name:PTPusherEventReceivedNotification
object:channel];
}
- (void)didReceiveEventNotification:(NSNotification *)notification // <-- never called
{
NSLog(#"event through delegate");
PTPusherEvent *event = [notification.userInfo objectForKey:PTPusherEventUserInfoKey];
}
After talking to the developer I found the problem:
In my code, the PTPusher instance is a local variable defined in the .m file.
However, it needs to be a strong variable defined in the .h file:
#property (strong) PTPusher* client;
Then in the .m file, you can easily use it (don't forget to synthesize it!):
self.client = [PTPusher pusherWithKey:#"de504dc5763aeef9ff52" delegate:self encrypted:YES];
[self.client connect];
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(didReceiveEventNotification:)
name:PTPusherEventReceivedNotification
object:self.client];
PTPusherChannel *channel = [client subscribeToChannelNamed:#"live_trades"];
Using NSNotificationCenter , it worked well till i have started to send very fast messages to other class.
What is fast ? its about 30-40 notifications in second. and i dont get even 1 of them .
is there other way to do that ?
should i update a global instead ?
//post data out .
- (void)post:(NSString*)string
{
NSLog(#"done"); //the log is printing
NSDictionary *userInfo = nil;
[[NSNotificationCenter defaultCenter] postNotificationName:#"connector"
object:string
userInfo:userInfo];
}
I know the observer is good cause same code worked before .
Thanks a lot .
If you're sending 30-40 notifications a second you should really think about your implementation again.
Heres some alternatives:
Creating your own delegates for callbacks
Using a block
The problem with NSNotificationCentre is that it sends the message to every observer - this can get slow and is generally used for updating views on state change (Login/Logout).
It looks like you setting the wrong object, Which should be the object that posts the notification (or nil). What I think you should be doing adding the string to userInfo:
NSDictionary *userInfo = #{#"somekey" : string };
[[NSNotificationCenter defaultCenter] postNotificationName:#"connector"
object:self
userInfo:userInfo];
i need a little help, i currently have a method; updateTrackInfo in my Mac OS X application which gets the artist name, the track name and duration of the track currently being played in iTunes
However i want the app to listen for the distributed iTunes notification; com.apple.iTunes.playerInfo then call the method updateTrackInfo when ever the notification is distributed by iTunes. Please could someone help me, on what i would need to write in both the header and implementation file.
Thanks, Sami.
You're looking for -[NSDistributedNotificationCenter addObserver:selector:name:object:]:
NSDistributedNotificationCenter *dnc = [NSDistributedNotificationCenter defaultCenter];
[dnc addObserver:self selector:#selector(updateTrackInfo:) name:#"com.apple.iTunes.playerInfo" object:nil];
Elsewhere in the same class...
- (void) updateTrackInfo:(NSNotification *)notification {
NSDictionary *information = [notification userInfo];
NSLog(#"track information: %#", information);
}
It even gives you a whole bunch of track information in the notification. Isn't that nice?
Thanks for your help, you helped me correct my code, I had this written up:
- (id) init {
self = [super init];
if (!self) return nil;
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(receiveNotification:)
name:#"com.apple.iTunes.playerInfo"
object:nil];
return self;}
- (void) receiveNotification:(NSNotification *) notification {
if ([#"com.apple.iTunes.playerInfo" isEqualToString:#"com.apple.iTunes.playerInfo"]) {
NSLog (#"Successfully received the test notification!");
}}
But it used NSNotificationCenter instead of NSDistributedNotificationCenter. Which is where I was going wrong.
Thanks, Sami.