I've two problems.
What can i do if i don't find a service at the first try?
Is this function called anyway:
- (void)peripheral:(CBPeripheral *)peripheral
didDiscoverServices:(NSError *)error{
if(error != nil){
[connectedDevice discoverServices:nil];
Is it more reliable to search for a service with UUID?
If i lost the connection is there any method called? Do i need to disconnect and reconnect again or only search for service and characteristics again?
Regards
Related
I was trying to communicate with a service with two way SSL.
I found the connection was cancelled immediately after the client (watch) provide the client certificate, by calling completeHandler(NSURLSessionAuthChallengeUseCredential, credential)
The error got is:
NSURLErrorDomain Code=-999 cancelled
But I've tried run the same piece of code on a phone, it did succeed.
Apart from that, other requests work fine on the watch.
Since, the frameworks on WatchOS and iOS are different, I am wondering if that might be an issue for WatchOS? Or is there anything specifically need to be configured for the watch?
Here is the code
- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential *))completionHandler
{
NSURLProtectionSpace *protectionSpace = [challenge protectionSpace];
NSString *authMethod = [protectionSpace authenticationMethod];
if (authMethod == NSURLAuthenticationMethodServerTrust) {
completionHandler(NSURLSessionAuthChallengeUseCredential, [NSURLCredential credentialForTrust:serverTrust]);
} else if (authMethod == NSURLAuthenticationMethodClientCertificate) {
// cancelled immediately after calling the method below.
completionHandler(NSURLSessionAuthChallengeUseCredential, self.credential);
} else {
completionHandler(NSURLSessionAuthChallengePerformDefaultHandling, nil);
}
}
Confirmed by Apple engineer.
It is an restriction of Watch OS. Two way SSL is not supported for now.
I have multiple BLE devices connected each 'notifying' when their battery state changes.
How can Identify which BLE is notifying when data is read after being notified of a change in state?
// Instance method to get the battery state
- (void) getBattery:(CBCharacteristic *)characteristic
{
//----------------
NSLog(#"getBattery");
//----------------
{
// Get the Battery Data
NSLog(#"Battery Level is : %# (HEX)" , characteristic.value);
}
}
This is the code reading the data when notified to...
Thanks for your answer, but it appears I'm only receiving data from the last service setup to notify from. Here is the calling code for Notify...
Hi, That's great. I can identify the device notifying when data has changed.
But, it appears that my code is only notifying and collecting data from the last characteristic identified.
Here is the calling code:
- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
{
// Retrieve the characteristic value for battery
if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:SR1_DEVICE_BATTERY_LEVEL_SERVICE_UUID]]) {
[self getBattery:characteristic];
}
}
When a peripheral sends a notification that a value has changed, the CBPeripheralDelegate method didUpdateValueForCharacteristic is invoked. This method includes a reference to the CBPeripheral. You don't show how you get from this method to your getBattery method, but you need pass the peripheral when you do.
You can also reference the peripheral property of the service property of the CBCharacteristic -
CBPeripheral *p=characteristic.service.peripheral;
Im using MCNearbyServiceBrowser and MCNearbyServiceAdvertiser to join two peers to a MCSession. I am able to send data between them using MCSession's sendData method. All seems to be working as expected until I randomly (and not due to any event I control) receive a MCSessionStateNotConnected via the session's MCSessionDelegate didChangeState handler. Additionally, the MCSession's connectedPeers array no longer has my peers.
Two questions: Why? and How do i keep the MCSession from disconnecting?
This is a bug, which I just reported to Apple. The docs claim the didReceiveCertificate callback is optional, but it's not. Add this method to your MCSessionDelegate:
- (void) session:(MCSession *)session didReceiveCertificate:(NSArray *)certificate fromPeer:(MCPeerID *)peerID certificateHandler:(void (^)(BOOL accept))certificateHandler
{
certificateHandler(YES);
}
The random disconnects should cease.
UPDATE After using a support ticket to Apple, they confirmed that calling sendData too often and with too much data can cause disconnects.
I have had disconnects when hitting break points and when backgrounding. Since the break points won't happen on the app store, you need to handle the backgrounding case by beginning a background task when your app is about to enter the background. Then end this task when your app comes back to the foreground. On iOS 7 this gives you about 3 background minutes which is better than nothing.
An additional strategy would be to schedule a local notification for maybe 15 seconds before your background time expires by using [[UIApplication sharedApplication] backgroundTimeRemaining], that way you can bring the user back into the app before it suspends and the multi peer framework has to be shutdown. Perhaps the local notification would warn them that their session will expire in 10 seconds or something...
If the background task expires and the app is still in the background, you have to tear down everything related to multi-peer connectivity, otherwise you will get crashes.
- (void) createExpireNotification
{
[self killExpireNotification];
if (self.connectedPeerCount != 0) // if peers connected, setup kill switch
{
NSTimeInterval gracePeriod = 20.0f;
// create notification that will get the user back into the app when the background process time is about to expire
NSTimeInterval msgTime = UIApplication.sharedApplication.backgroundTimeRemaining - gracePeriod;
UILocalNotification* n = [[UILocalNotification alloc] init];
self.expireNotification = n;
self.expireNotification.fireDate = [NSDate dateWithTimeIntervalSinceNow:msgTime];
self.expireNotification.alertBody = TR(#"Text_MultiPeerIsAboutToExpire");
self.expireNotification.soundName = UILocalNotificationDefaultSoundName;
self.expireNotification.applicationIconBadgeNumber = 1;
[UIApplication.sharedApplication scheduleLocalNotification:self.expireNotification];
}
}
- (void) killExpireNotification
{
if (self.expireNotification != nil)
{
[UIApplication.sharedApplication cancelLocalNotification:self.expireNotification];
self.expireNotification = nil;
}
}
- (void) applicationWillEnterBackground
{
self.taskId = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^
{
[self shutdownMultiPeerStuff];
[[UIApplication sharedApplication] endBackgroundTask:self.taskId];
self.taskId = UIBackgroundTaskInvalid;
}];
[self createExpireNotification];
}
- (void) applicationWillEnterForeground
{
[self killExpireNotification];
if (self.taskId != UIBackgroundTaskInvalid)
{
[[UIApplication sharedApplication] endBackgroundTask:self.taskId];
self.taskId = UIBackgroundTaskInvalid;
}
}
- (void) applicationWillTerminate
{
[self killExpireNotification];
[self stop]; // shutdown multi-peer
}
You'll also want this handler in your MCSession delegate due to Apple bug:
- (void) session:(MCSession*)session didReceiveCertificate:(NSArray*)certificate fromPeer:(MCPeerID*)peerID certificateHandler:(void (^)(BOOL accept))certificateHandler
{
if (certificateHandler != nil) { certificateHandler(YES); }
}
There are many causes of this, and the two answers thus far are both correct in my experience. Another which you'll find in other similar questions is this: Only one peer can accept another's invitation.
So, to clarify, if you set up an app where all devices are both advertisers and browsers, any devices can freely invite any others found to join a session. However, between any two given devices, only one device can actually accept the invitation and connect to the other device. If both devices accept each others' invitations they will disconnect within a minute or less.
Note that this limitation does not prevent the desired behavior because - unlike what my intuition stated before I built my multipeer implementation - when one device accepts an invitation and connects to another device they both become connected and receive connection delegate methods and can send each other messages.
Therefore, if you are connecting devices which both browse and advertise, send invitations freely but only accept one of a pair.
The problem of only accepting one of two invitations can be solved a myriad of ways. To begin, understand that you can pass any arbitrary object or dictionary (archived as data) as the context argument in an invitation. Therefore, both devices have access to any arbitrary information about the other (and of course itself). So, you could use at least these strategies:
simply compare: the display name of the peerID. But there's no guarantee these won't be equal.
store the date your multipeer controller was initialized and use that for comparison
give each peer a UUID and send this for comparison (my technique, in which each device - indeed each user of the app on a device - has a persistent UUID it employs).
etc - any object which supports both NSCoding and compare: will do fine.
I've been having similar problems. It seems though that if I have run my app on one iOS device, and connected to another, then quit and relaunch (say when I rerun from Xcode), then I am in a situation where I get a Connected message and then a Not Connected message a little later. This was throwing me off. But looking more carefully, I can see that the Not Connected message is actually meant for a different peerId than the one that has connected.
I think the problem here is that most samples I've seen just care about the displayName of the peerID, and neglect the fact that you can get multiple peerIDs for the same device/displayName.
I am now checking the displayName first and then verifying that the peerID is the same, by doing a compare of the pointers.
- (void)session:(MCSession *)session peer:(MCPeerID *)peerID didChangeState:(MCSessionState)state {
MyPlayer *player = _players[peerID.displayName];
if ((state == MCSessionStateNotConnected) &&
(peerID != player.peerID)) {
NSLog(#"remnant connection drop");
return; // note that I don't care if player is nil, since I don't want to
// add a dictionary object for a Not Connecting peer.
}
if (player == nil) {
player = [MyPlayer init];
player.peerID = peerID;
_players[peerID.displayName] = player;
}
player.state = state;
...
I was disconnecting immediately after I accepted the connection request. Observing the state, I saw it change from MCSessionStateConnected to MCSessionStateNotConnected.
I am creating my sessions with:
[[MCSession alloc] initWithPeer:peerID]
NOT the instantiation method dealing with security certificates:
- (instancetype)initWithPeer:(MCPeerID *)myPeerID securityIdentity:(NSArray *)identity encryptionPreference:(MCEncryptionPreference)encryptionPreference
Based on Andrew's tip above, I added the delegate method
- (void) session:(MCSession *)session didReceiveCertificate:(NSArray *)certificate fromPeer:(MCPeerID *)peerID certificateHandler:(void (^)(BOOL accept))certificateHandler {
certificateHandler(YES);
}
and the disconnects stopped.
I'm trying to set up a TCP connection to a local server, and since pretty much everyone agrees that Asyncsocket is the way to go, I went for it, too. However, I'm running into problems at the most basic level: the Asyncsocket instance doesn't have a local or remote address. I don't have much code, but this is what I do have:
- (void)viewDidLoad {
[super viewDidLoad];
AsyncSocket *socket = [[AsyncSocket alloc] initWithDelegate:self];
[socket connectToHost:#"www.google.com" onPort:80 error:nil];
}
- (BOOL)onSocketWillConnect:(AsyncSocket *)sock {
NSLog(#"%#", sock);
return YES;
}
- (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port {
NSLog(#"%#", host);
}
The following shows up in the console (from the NSLog in onSocketWillConnect):
AsyncSocket 0x298de0 local nowhere remote nowhere has queued 0 reads 0 writes, no current read, no current write, read stream 0x299720 not open, write stream 0x299aa0 not open, not connected
Where it says "nowhere", of course it should have IP addresses, but it doesn't. From examples online it looks like my code is fine, yet I get this "nowhere" thing when running on two computers and my phone, so I'm probably doing something wrong. Anybody have an idea?
Thanks!
edit: For clarification: if I use error reporting (by passing an NSError instance to "connectToHost:onPort:error" and NSLogging that), all I get back is (null).
Wow, that's embarrassing. I needed to make an ivar to store the AsyncSocket, because without it, it went out of scope after viewDidLoad completed, which was why my onSocket:didConnectToHost:port wasn't called.
This is with reference to the StackOverflow question Managing multiple asynchronous NSURLConnection connections
I have multiple asynchronous HTTP requests being made at the same time. All these use the same NSURLConnection delegate functions. (The receivedData object is different for each connection as specified in the other question above. In the delegate, I parse the receivedDate object, and do additional operations on those parsed strings)
Everything works fine for me so far, but I'm not sure if I need to do anything to ensure correct “multithreaded” behavior.
Is it possible that more than two connections will use the delegate at the same time? (I would think yes)
If yes, how is it resolved? (Does Cocoa do this automatically?)
Do I need to have additional checks in place to ensure that each request is handled “correctly”?
I enhanced the Three20 library to implement asynchronous connections across multiple threads in order to fetch data even if the user was playing with the UI. After many hours of chasing down random memory leaks that were detected within the CFNetwork framework I finally root caused the issue. I was occasionally losing track of responses and data.
Any data structures which are accessed by multiple threads must be protected by an appropriate lock. If you are not using locks to access shared data structures in a mutually exclusive manner then you are not thread safe. See the "Using Locks" section of Apple's Threading Programming Guide.
The best solution is to subclass NSURLConnection and add instance variables to store its associated response and response data. In each connection delegate method you then cast the NSURLConnection to your subclass and access those instance variables. This is guaranteed to be mutually exclusive because every connection will be bundled with its own response and data. I highly recommend trying this since it is the cleanest solution. Here's the code from my implementation:
#interface TTURLConnection : NSURLConnection {
NSHTTPURLResponse* _response;
NSMutableData* _responseData;
}
#property(nonatomic,retain) NSHTTPURLResponse* response;
#property(nonatomic,retain) NSMutableData* responseData;
#end
#implementation TTURLConnection
#synthesize response = _response, responseData = _responseData;
- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate {
NSAssert(self != nil, #"self is nil!");
// Initialize the ivars before initializing with the request
// because the connection is asynchronous and may start
// calling the delegates before we even return from this
// function.
self.response = nil;
self.responseData = nil;
self = [super initWithRequest:request delegate:delegate];
return self;
}
- (void)dealloc {
[self.response release];
[self.responseData release];
[super dealloc];
}
#end
/////////////////////////////////////////////////////////////////
////// NSURLConnectionDelegate
- (void)connection:(NSURLConnection*)connection
didReceiveResponse:(NSHTTPURLResponse*)response {
TTURLConnection* ttConnection = (TTURLConnection*)connection;
ttConnection.response = response;
ttConnection.responseData = [NSMutableData
dataWithCapacity:contentLength];
}
- (void)connection:(NSURLConnection*)connection
didReceiveData:(NSData*)data {
TTURLConnection* ttConnection = (TTURLConnection*)connection;
[ttConnection.responseData appendData:data];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
TTURLConnection* ttConnection = (TTURLConnection*)connection;
if (ttConnection.response.statusCode == 200) {
// Connection success
}
}
- (void)connection:(NSURLConnection *)connection
didFailWithError:(NSError *)error {
TTURLConnection* ttConnection = (TTURLConnection*)connection;
// Handle the error
}
Assuming you're launching all of the (asynchronous) connections on a single thread, then the delegate messages will all get posted in that thread's run loop. Therefore the delegate only needs to be able to deal with one message being handled at once; the run loop will hand one message off at a time. This means that while the order of the delegate messages is unknown and the next message could come from any connection object, there will be no concurrent execution of your delegate methods.
However, were you actually trying to use the same delegate object across multiple threads, rather than just using the asynchronous nature of the API, then you would need to deal with concurrent delegate methods.
Yes it's possible to have multiple connections. the notification object contains a pointer to the NSURLConnection that triggered the notification.
Internally I guess NSURLConnection listens to a socket and does something like this when it has data ready.
[your_delegate
performSelectorOnMainThread:#selector(connectionCallback:)
withObject:self
waitUntilDone:NO];
so you don't have to worry about it being multithreaded, NSURLConnection will take care of this. For simplicity I have written self, in the real world a NSNotification object is given.
You shouldn't have to do any checks related to multithreading.