NSXPCConnection debugging interruption/invalidation - xcode9

I am on XCode 9, OSX not iOS, Objective-C.
I have an XPC Service to talk to other applications.
XPC Services are completely new to me. I've read documentation and articles i found - still i'd need some help.
// NSXPC Connection stored as ivar
self.bridgeagent = [[NSXPCConnection alloc] initWithServiceName:#"com.myid.myapp.bridgeagent"];
self.bridgeagent.remoteObjectInterface = [NSXPCInterface interfaceWithProtocol:#protocol(bridgeagentProtocol)];
self.bridgeagent.exportedInterface = [NSXPCInterface interfaceWithProtocol:#protocol(bridgeagentProxyProtocol)];
self.bridgeagent.exportedObject = self;
[self.bridgeagent setInvalidationHandler:^{
NSLog(#"Bridgeagent invalidation handler!");
}];
[self.bridgeagent setInterruptionHandler:^{
NSLog(#"Bridgeagent interruption handler!");
}];
[self.bridgeagent resume];
The Service is called like this:
// openFile method is listed in corresponding protocol
[[self.bridgeagent remoteObjectProxyWithErrorHandler:^(NSError * _Nonnull error) {
NSLog(#"bridgeagent.openFile errorHandler: %#",error);
}] openFile:parameters withReply:^(NSDictionary *returnParameters) { // do something with result }];
The call works and the service does its job. However - now that the service works i want to dig into making it more stable (even if i don't face any issues right now).
Can someone explain to me
the difference between interruption and invalidation (don't get it when one or the other happens)
if there's a best practice to handle both cases
how to force both cases (for debugging)
Thank you for help

Answer to question 1:
[self.xpcConnection setInterruptionHandler:^{
// Connection interrupted. Backend (service) may have crashed.
// connection used to work but suddenly terminated
}];
[self.xpcConnection setInvalidationHandler:^{
// No one is listening. Is the backend running?
// connection cannot be established
}];
Answer to question 3:
interruption: make backend exit in the middle of a transaction (just before reply is sent)
invalidation: don't start backend (service) at all
Answer to question 2:
I have heard that in case "interruption" you should try to reestablish the connection. This can be useful when your service is a launch agent which gets restarted by launchd in case it crashed.
Actually in my program I don't act upon these cases but simply issue a warning message to the command line. My frontend is a cli program.
Alternatively you could log this warning in a logfile, for example with syslog. See 'man 3 syslog'. In my app I use my own logfile with configurable verbosity AND syslog.
kind regards,
Robert

Related

NSNetService says it is published, but it isn't visible on the network

I'm working on a little iOS app for my own use (initially, at least) and I thought I would use Bonjour to configure networking between two iOS devices.
My server's interface defines
NSNetService *netService;
and the implementation uses the following code to advertise its existence:
const NSString *kSEBonjourServiceDomain = #""; //use defaults
const NSString *kSEBonjourServiceName = #"_test._tcp.";
//...
netService = [[NSNetService alloc] initWithDomain:(NSString *)kSEBonjourServiceDomain type:(NSString *)kSEBonjourServiceName name:#"" port:sin.sin_port];
if (netService)
{
netService.delegate = self;
netService.includesPeerToPeer = YES;
[netService publish];
}
else NSLog(#"Failed to create NSNetService");
When I start the server, my NSNetService object does call the -netServiceDidPublish: delegate method, but when I use Discovery to browse the bonjour services on my network, my service doesn't appear. Apart from the const strings, this code is the same as some code in one of my Mac apps (which works as expected) and also very similar to Apple's sample code.
I've gone through all the options in Xcode's capabilities tab in case I needed to add something there, but I can't see anything relevant. I've also read a bunch of documents and tutorials that don't mention having to do anything more than that, but it wouldn't surprise me to learn that this only works on iOS if you set an obscure build setting to a string that you had to learn about by reading the Human Interface Guidelines for watchOS last September.
So, can anyone enlighten me? What am I missing?
Thanks in advance!
It turned out that due to a silly error elsewhere in my code, sin.sin_port was set to 0 by the time I was registering my NSNetService. Although NSNetService doesn't see this as a problem, it was causing the service to be ignored by service browsers.
So the answer is, a service with a port of 0 will register without error, but won't work.
Thanks to gaige for the assistance.

How to send/save data when user quits OS X application

I'm working on an OS X application after having worked almost exclusively on iOS apps. If the user quits, say by pressing Command-Q, how can I store some data locally and send some data to my server before the app truly goes out of memory?
On iOS I typically launch a background event when I detect the app going into the background. I've tried listening for "ApplicationWillTerminate" but it doesn't seem to afford me the time to send data.
Should I be intercepting the menu action and performing my work before quitting?
I realize this is a pretty basic question, but my Google-Foo has not led me to a straightforward answer.
applicationWillTerminate is indeed the method to clean up things before the app quits.
Alternatively for an asynchronous way implement applicationShouldTerminate, start you task to store and send the data asynchronously and return NSTerminateLater.
When the task is completed call
[NSApp replyToApplicationShouldTerminate:YES];
Here a snippet as example
- (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender
{
[self startTaskToSendDataWithCompletion:^() {
[NSApp replyToApplicationShouldTerminate:YES];
}];
return NSTerminateLater;
}

Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost."

I have an application which works fine on Xcode6-Beta1 and Xcode6-Beta2 with both iOS7 and iOS8. But with Xcode6-Beta3, Beta4, Beta5 I'm facing network issues with iOS8 but everything works fine on iOS7. I get the error "The network connection was lost.". The error is as follows:
Error: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo=0x7ba8e5b0 {NSErrorFailingURLStringKey=, _kCFStreamErrorCodeKey=57, NSErrorFailingURLKey=, NSLocalizedDescription=The network connection was lost., _kCFStreamErrorDomainKey=1, NSUnderlyingError=0x7a6957e0 "The network connection was lost."}
I use AFNetworking 2.x and the following code snippet to make the network call:
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager setSecurityPolicy:policy];
manager.requestSerializer = [AFHTTPRequestSerializer serializer];
manager.responseSerializer = [AFHTTPResponseSerializer serializer];
[manager POST:<example-url>
parameters:<parameteres>
success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#“Success: %#", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Error: %#", error);
}];
I tried NSURLSession but still receive the same error.
Restarting the simulator fixed the issue for me.
We had this exact error and it turned out to be an issue with the underlying HTTP implementation of NSURLRequest:
As far as we can tell, when iOS 8/9/10/11 receive an HTTP response with a Keep-Alive header, it keeps this connection to re-use later (as it should), but it keeps it for more than the timeout parameter of the Keep-Alive header (it seems to always keep the connection alive for 30 seconds.)
Then when a second request is sent by the app less than 30 seconds later, it tries to re-use a connection that might have been dropped by the server (if more than the real Keep-Alive has elapsed).
Here are the solutions we have found so far:
Increase the timeout parameter of the server above 30 seconds. It looks like iOS is always behaving as if the server will keep the connection open for 30 seconds regardless of the value provided in the Keep-Alive header. (This can be done for Apache by setting the KeepAliveTimeout option.
You can simply disable the keep alive mechanism for iOS clients based on the User-Agent of your app (e.g. for Apache: BrowserMatch "iOS 8\." nokeepalive in the mod file setenvif.conf)
If you don't have access to the server, you can try sending your requests with a Connection: close header: this will tell the server to drop the connection immediately and to respond without any keep alive headers. BUT at the moment, NSURLSession seems to override the Connection header when the requests are sent (we didn't test this solution extensively as we can tweak the Apache configuration)
For mine, Resetting content and settings of Simulator works.
To reset the simulator follow the steps:
iOS Simulator -> Reset Content and Settings -> Press Reset (on the
warning which will come)
The iOS 8.0 simulator runtime has a bug whereby if your network configuration changes while the simulated device is booted, higher level APIs (eg: CFNetwork) in the simulated runtime will think that it has lost network connectivity. Currently, the advised workaround is to simply reboot the simulated device when your network configuration changes.
If you are impacted by this issue, please file additional duplicate radars at http://bugreport.apple.com to get it increased priority.
If you see this issue without having changed network configurations, then that is not a known bug, and you should definitely file a radar, indicating that the issue is not the known network-configuration-changed bug.
Also have a problem with beta 5 and AFNetworking 1.3 when running on iOS 8 simulator that results in a connection error:
Domain=NSURLErrorDomain Code=-1005 "The network connection was lost."
The same code works fine on iOS 7 and 7.1 simulators and my debugging proxy shows that the failure occurs before a connection is actually attempted (i.e. no requests logged).
I have tracked the failure to NSURLConnection and reported bug to Apple. See line 5 in attached image:
.
Changing to use https allows connection from iOS 8 simulators albeit with intermittent errors.
Problem is still present in Xcode 6.01 (gm).
I was experiencing this problem while using Alamofire. My mistake was that I was sending an empty dictionary [:] for the parameters on a GET request, rather than sending nil parameters.
Hope this helps!
Opening Charles resolved the issue for me, which seems very strange...
Charles is an HTTP proxy / HTTP monitor / Reverse Proxy that enables a developer to view all of the HTTP and SSL / HTTPS traffic between their machine and the Internet. This includes requests, responses and the HTTP headers (which contain the cookies and caching information).
what solved the problem for me was to restart simulator ,and reset content and settings.
See pjebs comment on Jan 5 on Github.
Method1 :
if (error.code == -1005)
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
dispatch_group_t downloadGroup = dispatch_group_create();
dispatch_group_enter(downloadGroup);
dispatch_group_wait(downloadGroup, dispatch_time(DISPATCH_TIME_NOW, 5000000000)); // Wait 5 seconds before trying again.
dispatch_group_leave(downloadGroup);
dispatch_async(dispatch_get_main_queue(), ^{
//Main Queue stuff here
[self redoRequest]; //Redo the function that made the Request.
});
});
return;
}
Also some suggests to re-connect to the site,
i.e. Firing the POST request TWICE
Solution: Use a method to do connection to the site, return (id), if the network connection was lost, return to use the same method.
Method 2
-(id) connectionSitePost:(NSString *) postSender Url:(NSString *) URL {
// here set NSMutableURLRequest => Request
NSHTTPURLResponse *UrlResponse = nil;
NSData *ResponseData = [[NSData alloc] init];
ResponseData = [NSURLConnection sendSynchronousRequest:Request returningResponse:&UrlResponse error:&ErrorReturn];
if ([UrlResponse statusCode] != 200) {
if ([UrlResponse statusCode] == 0) {
/**** here re-use method ****/
return [self connectionSitePost: postSender Url: URL];
}
} else {
return ResponseData;
}
}
On 2017-01-25 Apple released a technical Q&A regarding this error:
Apple Technical Q&A QA1941
Handling “The network connection was lost” Errors
A: NSURLErrorNetworkConnectionLost is error -1005 in the NSURLErrorDomain error domain, and is displayed to users as “The network connection was lost”. This error means that the underlying TCP connection that’s carrying the HTTP request disconnected while the HTTP request was in progress (see below for more information about this). In some circumstances NSURLSession may retry such requests automatically (specifically, if the request is idempotent) but in other circumstances that’s not allowed by the HTTP standards.
https://developer.apple.com/library/archive/qa/qa1941/_index.html#//apple_ref/doc/uid/DTS40017602
I was getting this error as well, but on actual devices rather than the simulator. We noticed the error when accessing our heroku backend on HTTPS (gunicorn server), and doing POSTS with large bodys (anything over 64Kb). We use HTTP Basic Auth for authentication, and noticed the error was resolved by NOT using the didReceiveChallenge: delegate method on NSURLSession, but rather baking in the Authentication into the original request header via adding Authentiation: Basic <Base64Encoded UserName:Password>. This prevents the necessary 401 to trigger the didReceiveChallenge: delegate message, and the subsequent network connection lost.
I had the same problem. I don't know how AFNetworking implements https request, but the reason for me is the NSURLSession's cache problem.
After my application tracking back from safari and then post a http request, "http load failed 1005" error will appear.
If I stop using "[NSURLSession sharedSession]", but to use a configurable NSURLSession instance to call "dataTaskWithRequest:" method as follow, the problem is solved.
NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
config.requestCachePolicy = NSURLRequestReloadIgnoringLocalCacheData;
config.URLCache = nil;
self.session = [NSURLSession sessionWithConfiguration:config];
Just remember to set config.URLCache = nil;.
I have this issue also, running on an iOS 8 device.
It is detailed some more here and seems to be a case of iOS trying to use connections that have already timed out.
My issue isn't the same as the Keep-Alive problem explained in that link, however it seems to be the same end result.
I have corrected my problem by running a recursive block whenever I receive an error -1005 and this makes the connection eventually get through even though sometimes the recursion can loop for 100+ times before the connection works, however it only adds a mere second onto run times and I bet that is just the time it takes the debugger to print the NSLog's for me.
Here's how I run a recursive block with AFNetworking:
Add this code to your connection class file
// From Mike Ash's recursive block fixed-point-combinator strategy https://gist.github.com/1254684
dispatch_block_t recursiveBlockVehicle(void (^block)(dispatch_block_t recurse))
{
// assuming ARC, so no explicit copy
return ^{ block(recursiveBlockVehicle(block)); };
}
typedef void (^OneParameterBlock)(id parameter);
OneParameterBlock recursiveOneParameterBlockVehicle(void (^block)(OneParameterBlock recurse, id parameter))
{
return ^(id parameter){ block(recursiveOneParameterBlockVehicle(block), parameter); };
}
Then use it likes this:
+ (void)runOperationWithURLPath:(NSString *)urlPath
andStringDataToSend:(NSString *)stringData
withTimeOut:(NSString *)timeOut
completionBlockWithSuccess:(void (^)(AFHTTPRequestOperation *operation, id responseObject))success
failure:(void (^)(AFHTTPRequestOperation *operation, NSError *error))failure
{
OneParameterBlock run = recursiveOneParameterBlockVehicle(^(OneParameterBlock recurse, id parameter) {
// Put the request operation here that you want to keep trying
NSNumber *offset = parameter;
NSLog(#"--------------- Attempt number: %# ---------------", offset);
MyAFHTTPRequestOperation *operation =
[[MyAFHTTPRequestOperation alloc] initWithURLPath:urlPath
andStringDataToSend:stringData
withTimeOut:timeOut];
[operation setCompletionBlockWithSuccess:
^(AFHTTPRequestOperation *operation, id responseObject) {
success(operation, responseObject);
}
failure:^(AFHTTPRequestOperation *operation2, NSError *error) {
if (error.code == -1005) {
if (offset.intValue >= numberOfRetryAttempts) {
// Tried too many times, so fail
NSLog(#"Error during connection: %#",error.description);
failure(operation2, error);
} else {
// Failed because of an iOS bug using timed out connections, so try again
recurse(#(offset.intValue+1));
}
} else {
NSLog(#"Error during connection: %#",error.description);
failure(operation2, error);
}
}];
[[NSOperationQueue mainQueue] addOperation:operation];
});
run(#0);
}
You'll see that I use a AFHTTPRequestOperation subclass but add your own request code. The important part is calling recurse(#offset.intValue+1)); to make the block be called again.
If the problem is occurring on a device, check if traffic is going through a proxy (Settings > Wi-Fi > (info) > HTTP Proxy). I had my device setup to use with Charles, but forgot about the proxy. Seems that without Charles actually running this error occurs.
I was connecting via a VPN. Disabling the VPN solved the problem.
I had same problem. Solution was simple, I've set HTTPBody, but haven't set HTTPMethod to POST. After fixing this, everything was fine.
I had to exit XCode, delete DerivedData folder contents (~/Library/Developer/Xcode/DerivedData or /Library/Developer/Xcode/DerivedData) and exit simulator to make this work.
If anyone is getting this error while uploading files to a backend server, make sure the receiving server has a maximum content size that is allowable for your media. In my case, NGINX required a higher client_max_body_size. NGINX would reject the request before the uploading was done so no error code came back.
I was hitting this error when passing an NSURLRequest to an NSURLSession without setting the request's HTTPMethod.
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:urlComponents.URL];
Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost."
Add the HTTPMethod, though, and the connection works fine
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:urlComponents.URL];
[request setHTTPMethod:#"PUT"];
I was facing the same issue,
I have enabled Network Link Conditioner for slow network testing for the app. That was creating this error some times,
When i have disabled it from Settings > Developer > Network Link Conditioner, it solved my problem.
Hope this help someone.
On top of all the answers i found one nice solution. Actually The issue related to network connection fail for iOS 12 onword is because there is a bug in the iOS 12.0 onword. And it Yet to resolved. I had gone through the git hub community for AFNetworking related issue when app came from background and tries to do network call and fails on connection establish. I spend 3 days on this and tries many things to get to the root cause for this and found nothing. Finally i got some light in the dark when i red this blog https://github.com/AFNetworking/AFNetworking/issues/4279
It is saying that there is a bug in the iOS 12. Basically you cannot expect a network call to ever complete if the app os not in foreground. And due to this bug the network calls get dropped and we get network fails in logs.
My best suggestion to you is provide some delay when your app are coming from background to foreground and there is network call. Make that network call in the dispatch async with some delay. You'll never get network call drop or connection loss.
Do not wait for Apple to let this issue solve for iOS 12 as its still yet to fix.
You may go with this workaround by providing some delay for your network request being its NSURLConnection, NSURLSession or AFNetworking or ALAMOFIRE. Cheers :)
I was having this issue for the following reason.
TLDR: Check if you are sending a GET request that should be sending the parameters on the url instead of on the NSURLRequest's HTTBody property.
==================================================
I had mounted a network abstraction on my app, and it was working pretty well for all my requests.
I added a new request to another web service (not my own) and it started throwing me this error.
I went to a playground and started from the ground up building a barebones request, and it worked. So I started moving closer to my abstraction until I found the cause.
My abstraction implementation had a bug:
I was sending a request that was supposed to send parameters encoded in the url and I was also filling the NSURLRequest's HTTBody property with the query parameters as well.
As soon as I removed the HTTPBody it worked.
Whenever got error -1005 then need to call API Again.
AFHTTPRequestOperationManager *manager =
[AFHTTPRequestOperationManager manager];
[manager setSecurityPolicy:policy];
manager.requestSerializer = [AFHTTPRequestSerializer serializer];
manager.responseSerializer = [AFHTTPResponseSerializer serializer];
[manager POST:<example-url>
parameters:<parameteres>
success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#“Success: %#", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Error: %#", error);
if (error.code == -1005) {
// Call method again...
}
}];
You need to Add your code to call function again. MakeSure that you were call method once otherwise its call recursive loop.
I faced the same issue while calling using my company's server from iOS 12 app with a physical device. The problem was that the server hard disk was full. Freeing space in the server solved the problem.
I found the same error in another situation I think due to a timeout not parametrizable through the standard Networking API provided by Apple (URLSession.timeoutIntervalForRequest and URLSession.timeoutIntervalForResource). Even there.. made server answer faster solved the problem
This might be a problem of the parameter that you are passing to request body. I was also facing the same issue. But then I came across CMash's answer here https://stackoverflow.com/a/34181221/5867445 and I changed my parameter and it works.
Issue in a parameter that I was passing is about String Encoding.
Hope this helps.
My problem was on the server. I was using Python's BaseHTTPRequestHandler class and I wasn't sending a body in the response. My problem was solved when I put an empty body like the following.
def do_POST(self):
content_len = int(self.headers.get('Content-Length'))
post_body = self.rfile.read(content_len)
msg_string = post_body.decode("utf-8")
msg_json = json.loads(msg_string)
self.send_response(200)
self.end_headers() #this and the following lines were missing
self.wfile.write(b'')
I had the same issue, the problem was bug of Alomofire and NSUrlSession. When you returning back to app from safari or email you need to wait nearly 2 seconds to do you network response via Alamofire
DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
Your network response
}
Got the issue for months, and finally discovered that when we disable DNSSEC on our api domain, everything was ok.

Actionscript 4: NetConnection.connect(...) does not fire a NetStatusEvent event

I downloaded the red5-recorder (http://www.red5-recorder.com/) , which fails to allow me to start recording. After debugging I found that the netconnection, needed to record to a media server, created does not fire a NetStatusEvent event, so essentially it fails silently. I have implemented the connection with the following minimal working example:
trace("make net connection");
nc = new NetConnection();
nc.client = { onBWDone: function():void{ trace("bandwidth check done.") } };
trace("add event listener");
nc.addEventListener(NetStatusEvent.NET_STATUS, function(event:NetStatusEvent) {
trace("handle");
});
trace("connect!");
nc.connect("rtmp://localshost/oflaDemo/test/");
trace("connect done");
The output of this piece of code is:
make net connection
add event listener
connect!
connect done
The actionscript api states that the connect-call always fires such an event:
http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/net/NetConnection.html#includeExamplesSummary
Moreover, the netconnection is not 'connected' (a state of the NetConnection object) 10 seconds after the call. I also took a look at this: NetConnect fails silently in Flash when called from SilverLight But the fix suggested by the author, swapping rtmp and http in the connection uri, do not work. Also, I tested the uri and in fact the exact same code sniplet in a personal project, where it did work. I just can not seem to find why connecting to a media server fails silently in the red5-recorder project.
The awkward part is that if I pass some random string as a conenction uri, still nothing happens (no event, no exception, no crash). Also not setting nc.client becore nc.connect(), which caused exceptions in my experience, did not cause exceptions.
Any suggestions are welcome.
You are setting the address to localshost instead localhost.
nc.connect("rtmp://localshost/oflaDemo/test/");
Correct address:
nc.connect("rtmp://localhost/oflaDemo/test/");

What can you do in CoreBluetooth background delegate calls?

I am using Core Bluetooth in my project. I have included Session Backgrounding to avail its background mode functionality. I have observed that the delegate for peripheral disconnection,
- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;
gets called in the background mode. However any code I write in this method is not executed except for NSLogs. Can somebody explain exactly what kind of code can be executed here?
My aim is to send this disconnection notification to my server.
Ok it seems it was some issue at my end. According the the documentation your app is woken (in the background) for around 10 seconds when it gets a bluetooth related delegate call.
You can use this time to perform any non view updating task and even request for additional time using beginBackgroundTaskWithExpirationHandler.
My code looks like this.
if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
[self sendEmailInBackground:peripheral]; //Code to send a server request
return;
}
and its working in the background mode. This also works when the phone is in lock state.

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