How to check for network synchronously? I want the network checking to block the calling thread and return the correct result
I tried tonymillion's Reachability and AFNetworkReachabilityManager but they all use callback block. It means the reachability status is unknown before the callback.
I want to check network at applicationDidFinishLaunchingWithOptions: but at this point, reachability is AFNetworkReachabilityStatusUnknown (AFNetworkReachabilityManager) or not reliable (tonymillion's Reachability)
I see that the only way is to perform NSURLConnection against some host (google.com for example) like this Check for internet connection - iOS SDK
Are there any better way?
To answer my own question: It is reliable
Read this Technical Q&A QA1693 Synchronous Networking On The Main Thread
reachability — The System Configuration framework reachability API
() operates synchronously
by default. Thus, seemingly innocuous routines like
SCNetworkReachabilityGetFlags can get you killed by the watchdog. If
you're using the reachability API, you should use it asynchronously.
This involves using the SCNetworkReachabilityScheduleWithRunLoop
routine to schedule your reachability queries on the run loop
So we can use it like this iOS: Check whether internet connection is available
- (BOOL) isConnectionAvailable
{
SCNetworkReachabilityFlags flags;
BOOL receivedFlags;
SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(CFAllocatorGetDefault(), [#"dipinkrishna.com" UTF8String]);
receivedFlags = SCNetworkReachabilityGetFlags(reachability, &flags);
CFRelease(reachability);
if (!receivedFlags || (flags == 0) )
{
return FALSE;
} else {
return TRUE;
}
}
Related
I am updating an existing iOS VOIP application to use CallKit with PJSIP 2.6 and PJSUA2.
After some effort, the CallKit implementation seems to be working as expected. Incoming calls can be accepted or declined, and if accepted, will be connected and controlled with an in-app active call view controller.
The audio, however, does not appear to be properly connected at the pjsip end. There is no audio coming in from, or going out to the remote caller. The microphone audio appears to be routed back to the iPhone speaker.
The SIP audio ports should be connecting in callback function onCallMediaState:
virtual void onCallMediaState(OnCallMediaStateParam &prm) {
CallInfo ci = getInfo();
AudioMedia* audio_media = 0;
for (unsigned i = 0; i < ci.media.size(); i++) {
if (ci.media[i].type==PJMEDIA_TYPE_AUDIO && ( ci.media[i].status == PJSUA_CALL_MEDIA_ACTIVE ||
ci.media[i].status ==PJSUA_CALL_MEDIA_REMOTE_HOLD)) {
try {
audio_media = static_cast<AudioMedia*>(getMedia(i));
if(audio_media != 0)
{
Endpoint::instance().audDevManager().getCaptureDevMedia().startTransmit(*audio_media);
audio_media->startTransmit(Endpoint::instance().audDevManager().getPlaybackDevMedia());
}
} catch (std::exception ex) {
continue;
}
}
}
}
As described in Ticket#1941 at:
https://trac.pjsip.org/repos/ticket/1941:
I set the audio devices using:
ep->audDevManager().setNullDev();
immediately after the initialization of the Endpoint class (ep->libInit(epConfig);), and then:
I attempt to set the devices using pjsua_set_snd_dev() in CXProvider’s didActivate function, like this:
-(void) setSipSoundDevices {
pj_status_t status;
int captDev, playDev;
pjsua_get_snd_dev(&captDev, &playDev);
Endpoint::instance().audDevManager().setPlaybackDev(playDev);
Endpoint::instance().audDevManager().setCaptureDev(captDev);
}
pjsua_get_snd_dev(&captDev, &playDev) returns -99, -99 and the audio does not connect.
My question is this. How can I properly hook up the remote audio sources or ports, on an incoming call using PJSIP 2.6 and CallKit?
Might 2.5.5 work better in this regard?
Any insights are appreciated.
By and by I got the incoming call audio working properly. The crux of the matter was that even though the documentation from both Apple and SIP say that the audio has to be handled on the iOS end, you still have to set the SIP audio devices in the SIP layer in the provider delegate 'didActivate' and 'didDeactivate' functions. Because I use the PJSUA C++ layer, I had to drill down through the objc-c++ bridging layer to provide this functionality. ie.
-(void) activateSipSoundDevices {
pj_status_t status = pjsua_set_snd_dev(0, 0);
}
-(void) deactivateSipSoundDevices {
pj_status_t status = pjsua_set_null_snd_dev();
}
When initializing the SIP Account, be sure to set the null sound devices like:
ep->audDevManager().setNullDev();
Hope this helps.
I'm using the Reachability class provided here by Apple in my iOS project. I call its currentReachabilityStatus method always before trying to call my own REST web services:
- (NetworkStatus)currentReachabilityStatus
{
NSAssert(_reachabilityRef != NULL, #"currentNetworkStatus called with NULL SCNetworkReachabilityRef");
NetworkStatus returnValue = NotReachable;
SCNetworkReachabilityFlags flags;
if (SCNetworkReachabilityGetFlags(_reachabilityRef, &flags))
{
if (_alwaysReturnLocalWiFiStatus)
{
returnValue = [self localWiFiStatusForFlags:flags];
}
else
{
returnValue = [self networkStatusForFlags:flags];
}
}
return returnValue;
}
In turn, I call this method from a custom class I made for convenience:
+ (BOOL)checkNetStatus
{
Reachability *reach = [Reachability reachabilityForInternetConnection];
NetworkStatus status = [reach currentReachabilityStatus];
return [self boolFromStatus:status];
}
I'm performing some tests in an iPhone, enabling the flight mode in its Settings, and then when the app is back to foreground, that method is called several times (my app retries to call the web services if no reachability until they become reachable) and finally I get an EXC_BAD_ACCESS exception at line if (SCNetworkReachabilityGetFlags(_reachabilityRef, &flags)), and the app crashes.
I don't understand exactly why, because currentReachabilityStatus is called several times before I get the exception and the crash, could it be because it is being called a lot of times and too fast? How could I solve this?
I need help, thanks in advance.
EDIT: whenever I'm going to call of my RESTful services, I do something like this:
- (void)callWebService
{
if ([MyReachabilityManager checkNetStatus]) {
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
MyServiceWrapper *requestService = [[MyServiceWrapper alloc] initWithServiceUrl];
[requestService queryService];
}
else {
[self keepRequestingMyService]; // this calls this method again until a timeout
}
}
Something similar happened to me, one of my application crashed while switching to Airplane mode and to Wifi frequently (Happened if the Wi-Fi is having low signal strength).
In my case the crash is caused by the NSAssert, the _reachabilityRef was null, so the assert condition was failing:
NSAssert(_reachabilityRef != NULL, #"currentNetworkStatus called with NULL SCNetworkReachabilityRef");
I just removed that and re-wrote that method by adding a extra null check for _reachabilityRef
I had the same: app SOMETIMES crashes when releasing reachabilityRef. Seems like it should be NULL but it is not?
After experimenting i found if I added something in Reachability.h interface (originally it had nothing):
#interface Reachability : NSObject{
BOOL dummy;
}
it stopped crashing, could you try that and report if it helps?
I use XCode 7.1.1
I have an iOS app that makes some small network requests on app launch (resource updates, etc). If the user turns off cellular access for the app in iOS Settings, they get a prompt from iOS about network usage every time they launch. Is there a way to know programmatically that cellular data for this app has been disabled, so that I can disable the requests at startup?
So I found this on the apple dev forums from an Apple engineer (https://devforums.apple.com/message/1059332#1059332).
Another developer wrote in to DTS and thus I had a chance to
investigate this in depth. Alas, the news is much as I expected:
there is no supported way to detect that your app is in this state.
Nor is there a way to make a "no user interaction" network connection,
that is, request that the connection fail rather than present UI like
this. If these limitations are causing problems for your app, I
encourage you to file a bug describing your specific requirements.
https://developer.apple.com/bug-reporting/
So it looks like it is not possible to detect if cellular data for your app has been turned off.
Edit
I filed a radar for this requesting that it be added. I just got this notification in my radar
We believe this issue has been addressed in the latest iOS 9 beta.
I looked through the API diffs, but so far I can't find the new API.
As of iOS9, the capability to check the setting to enable/disable use of cellular data for your app (Settings/Cellular/AppName) is available using Apple's CTCellularData class. The following code will set cellularDataRestrictedState when it is run initially and then set it and log whenever it changes:
import CoreTelephony
var cellularDataRestrictedState = CTCellularDataRestrictedState.restrictedStateUnknown
let cellState = CTCellularData.init()
cellState.cellularDataRestrictionDidUpdateNotifier = { (dataRestrictedState) in
if cellularDataRestrictedState != .restrictedStateUnknown { // State has changed - log to console
print("cellularDataRestrictedState: " + "\(dataRestrictedState == .restrictedStateUnknown ? "unknown" : dataRestrictedState == .restricted ? "restricted" : "not restricted")")
}
cellularDataRestrictedState = dataRestrictedState
}
Unfortunately (as of iOS11) this seems to check only the state of the app's switch - if your app's switch is set to enabled and the user switches the Cellular Data master switch to disabled, this API will return the app's state as being "not restricted".
Just wanted to add an Objective C version of the above Swift code for future travellers.
- (void)monitorCanUseCellularData {
if (GCIsiOS9) {
CTCellularData *cellularData = [[CTCellularData alloc] init];
NSLog(#"%ld", cellularData.restrictedState);
// 0, kCTCellularDataRestrictedStateUnknown
[cellularData setCellularDataRestrictionDidUpdateNotifier:^(CTCellularDataRestrictedState state) {
NSLog(#"%ld", state);
self.canUseCellularData = cellularData.restrictedState ==2?true:false;
}];
}
}
I have found that the CTCellularData class needs some time to get to the correct value. In my implementation I call the didUpdateNotifier very early after appDidFinishLaunching. By the time my networking call are returning with errors I definitely have a correct value for the restricted state.
class CellularRestriction: NSObject {
private static var cellularData = CTCellularData()
private static var currentState = CTCellularDataRestrictedState.restrictedStateUnknown
static var isRestricted: Bool {
currentState = cellularData.restrictedState
return currentState == .restricted
}
static func prepare() {
if currentState == .restrictedStateUnknown {
cellularData.cellularDataRestrictionDidUpdateNotifier = { state in
currentState = cellularData.restrictedState // This value may be inconsistent, however the next read of isRestricted should be correct.
}
}
}
}
You can detect if cellular data disabled using NWPathMonitor class. (https://developer.apple.com/documentation/network/nwpathmonitor)
let cellMonitor = NWPathMonitor(requiredInterfaceType: .cellular)
cellMonitor.pathUpdateHandler = { path in
self.isCellConnected = path.status == .satisfied
}
Adding to dirkgroten's answer, you can use the Apple Reachability class, found here:
https://developer.apple.com/Library/ios/samplecode/Reachability/Introduction/Intro.html
It uses SCNetworkReachability, and is very straight forward to use, it will detect connectivity via Cell and WiFi as you will need to check both at start up.
There are lots of frameworks out there that will give you the status of your network connectivity, and of course you can roll your own. I've found AFNetworking to be one of the best. It has a singleton class called AFNetworkReachabilityManager that abstracts some of the complexities for you. Specifically you'll want to look at the two boolean properties:
reachableViaWWAN
reachableViaWiFi
There is also a reachability changed status block that you can set:
– setReachabilityStatusChangeBlock:
AFNetworking Github
AFNetworkReachabilityManager
I tested different frameworks, e.g.
https://github.com/tonymillion/Reachability
https://github.com/VerticodeLabs/VCLReachability
https://github.com/kstenerud/KSReachability
and I would like to know if a host is reachable. On my iPhone, I set my iMac as proxy (Charles) and block or don't block the connections, but the reachability is always YES. Only if I set a non-existing host, it returns NO. But if the host exists but I block the connection to it, I always get isReachable. Isn't there a way to check if the host is really reachable?
If I try with KSReachability, I'm doing the following:
self.reachability = [KSReachability reachabilityToHost:#"www.stackoverflow.com"];
self.reachability.notificationName = kDefaultNetworkReachabilityChangedNotification;
self.reachability.onReachabilityChanged = ^(KSReachability *reachability) {
NSLog(#"isReachable: %i", reachability.reachable);
};
I always get isReachable: 1 there with the following configuration:
connected to Wifi
configured my iMac as HTTP-Proxy
blocking www.stackoverflow.com in my Charles Proxy
When I try to reach www.stackoverflow.com in Safari, the page can't be opened (as expected). I would expect the reachability to be false (isReachable: 0) in this case.
EDIT
So the most important question for me is - how to achieve the behavior I'm expecting? I.e. that the app continuously checks if the given host is really reachable?
The code statement:
self.reachability = [KSReachability reachabilityToHost:#"www.stackoverflow.com"];
actually calls below method:
SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL,
[hostName UTF8String]);
SCNetworkReachability reference says:
The SCNetworkReachability programming interface allows an application
to determine the status of a system's current network configuration
and the reachability of a target host. A remote host is considered
reachable when a data packet, sent by an application into the network
stack, can leave the local device. Reachability does not guarantee
that the data packet will actually be received by the host.
The explanation clears that iOS system doesn't send any request to outside world to check the reachability. It just tells that data packet can leave the device or not. If system were to send the request it automatically means that it is connected to network.
You can verify this by mentioning a valid host like "www.stackoverflow.com" and check in charles (first unblock it) that no request is sent.You can also check with other valid host names like "www.abcdefgh.com" (verify this by running it in Safari and see in charles) it also gives you the reachability but charles shows no request.Also if you put http:// before any valid host, something like "http://www.stackoverflow.com" it will also fails reachability. So it is clear that it is not an outgoing http request. If system has to send a request outside then what's the point of providing the class? A developer could have created a network connection and try to connect to a host and see if it passes or fails.
However it is interesting that if an invalid host like "www.hjjkhkhk.com" is provided iOS system gives reachability as false. Now the question is how iOS system finds a valid or invalid host without sending any query to outside world? May be it is periodically caching a list of DNS ranges??? Highly improbable to me.
In your AppDelegate add this method:
#import "Reachability.h"
-(NSString *)checkNetworkConnectivity
{
NSString *networkValue;
Reachability *rc = [Reachability reachabilityWithHostName:#"www.stackoverflow.com"];
NetworkStatus internetStatus = [rc currentReachabilityStatus];
if(internetStatus==0)
{
networkValue = #"NoAccess";
}
else if(internetStatus==1)
{
networkValue = #"ReachableViaWiFi";
} else if(internetStatus==2)
{
networkValue = #"ReachableViaWWAN";
}
else
{
networkValue = #"Reachable";
}
return networkValue;
}
Checking if the host is reachable
NSString *netStr = [appDelegate checkNetworkConnectivity];
if([netStr isEqualToString:#"NoAccess"])
{
[appDelegate callNoNetworkAlert];
}
Firstly, unless we see some code, we cannot make sure what you're doing, you're doing the right way. However I will assume you are doing it correctly.
Secondly, you should test what FreeNickname has suggested in his comment. Maybe it's not actually unreachable, and the reachability is acting correctly, when you expect a different response.
Last, but very important, from the Reachability docs :
Note: Reachability cannot tell your application if you can connect to a particular host, only that an interface is available that might allow a connection, and whether that interface is the WWAN.
What it means is that, even though your server might not be returning any responses, Reachability does NOT check that. It only checks if your server is available , such that a packet can be sent. What it does with that packet is of no concern to Reachability. If Reachability is able to transmit the entire packet, it assumes your host is reachable. It will return unreachable iff your server is down, disconnected, or does not exist.
I would like to add that To listen the Network changes at Runtime, you need to listen to the Notifications that tell you that a Network state has been changed.
This is how you can do this :
Implement a listener in AppDelegate file.
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(reachabilityChanged:)
name:kReachabilityChangedNotification object:nil];
Now reachabilityChanged will be called when there is a change in Network status (perhaps connectivity of internet connection or it's disconnection). You can do appropriate handling in reachabilityChanged event
like:
- (void) reachabilityChanged:(NSNotification *)note
{
Reachability* reachability = [note object];
if (reachability == self.hostReachability)
{
isHostReachable = YES; //A flag to keep track of connectivity
}
if (reachability == self.internetReachability)
{
isInternetAvailable = YES;
}
if (reachability == self.wifiReachability)
{
isWifiAvailable = YES;
}
//If all are true that means we have host and Internet available
if (isHostReachable && isInternetAvailable && isWifiAvailable)
{
isInternetAvailable = true;
}
}
Hope this will help you.
AFNetworking
A delightful iOS and OS X networking framework
http://afnetworking.com
Network Reachability Manager
AFNetworkReachabilityManager monitors the reachability of domains, and addresses for both WWAN and WiFi network interfaces.
Shared Network Reachability
[[AFNetworkReachabilityManager sharedManager] setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status)
{
NSLog(#"Reachability: %#", AFStringFromNetworkReachabilityStatus(status));
}];
HTTP Manager Reachability
NSURL *baseURL = [NSURL URLWithString:#"http://example.com/"];
AFHTTPRequestOperationManager *manager = [[AFHTTPRequestOperationManager alloc] initWithBaseURL:baseURL];
NSOperationQueue *operationQueue = manager.operationQueue;
[manager.reachabilityManager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status)
{
switch (status)
{
case AFNetworkReachabilityStatusReachableViaWWAN:
case AFNetworkReachabilityStatusReachableViaWiFi:
[operationQueue setSuspended:NO];
break;
case AFNetworkReachabilityStatusNotReachable:
default:
[operationQueue setSuspended:YES];
break;
}
}];
I have an iOS app that makes some small network requests on app launch (resource updates, etc). If the user turns off cellular access for the app in iOS Settings, they get a prompt from iOS about network usage every time they launch. Is there a way to know programmatically that cellular data for this app has been disabled, so that I can disable the requests at startup?
So I found this on the apple dev forums from an Apple engineer (https://devforums.apple.com/message/1059332#1059332).
Another developer wrote in to DTS and thus I had a chance to
investigate this in depth. Alas, the news is much as I expected:
there is no supported way to detect that your app is in this state.
Nor is there a way to make a "no user interaction" network connection,
that is, request that the connection fail rather than present UI like
this. If these limitations are causing problems for your app, I
encourage you to file a bug describing your specific requirements.
https://developer.apple.com/bug-reporting/
So it looks like it is not possible to detect if cellular data for your app has been turned off.
Edit
I filed a radar for this requesting that it be added. I just got this notification in my radar
We believe this issue has been addressed in the latest iOS 9 beta.
I looked through the API diffs, but so far I can't find the new API.
As of iOS9, the capability to check the setting to enable/disable use of cellular data for your app (Settings/Cellular/AppName) is available using Apple's CTCellularData class. The following code will set cellularDataRestrictedState when it is run initially and then set it and log whenever it changes:
import CoreTelephony
var cellularDataRestrictedState = CTCellularDataRestrictedState.restrictedStateUnknown
let cellState = CTCellularData.init()
cellState.cellularDataRestrictionDidUpdateNotifier = { (dataRestrictedState) in
if cellularDataRestrictedState != .restrictedStateUnknown { // State has changed - log to console
print("cellularDataRestrictedState: " + "\(dataRestrictedState == .restrictedStateUnknown ? "unknown" : dataRestrictedState == .restricted ? "restricted" : "not restricted")")
}
cellularDataRestrictedState = dataRestrictedState
}
Unfortunately (as of iOS11) this seems to check only the state of the app's switch - if your app's switch is set to enabled and the user switches the Cellular Data master switch to disabled, this API will return the app's state as being "not restricted".
Just wanted to add an Objective C version of the above Swift code for future travellers.
- (void)monitorCanUseCellularData {
if (GCIsiOS9) {
CTCellularData *cellularData = [[CTCellularData alloc] init];
NSLog(#"%ld", cellularData.restrictedState);
// 0, kCTCellularDataRestrictedStateUnknown
[cellularData setCellularDataRestrictionDidUpdateNotifier:^(CTCellularDataRestrictedState state) {
NSLog(#"%ld", state);
self.canUseCellularData = cellularData.restrictedState ==2?true:false;
}];
}
}
I have found that the CTCellularData class needs some time to get to the correct value. In my implementation I call the didUpdateNotifier very early after appDidFinishLaunching. By the time my networking call are returning with errors I definitely have a correct value for the restricted state.
class CellularRestriction: NSObject {
private static var cellularData = CTCellularData()
private static var currentState = CTCellularDataRestrictedState.restrictedStateUnknown
static var isRestricted: Bool {
currentState = cellularData.restrictedState
return currentState == .restricted
}
static func prepare() {
if currentState == .restrictedStateUnknown {
cellularData.cellularDataRestrictionDidUpdateNotifier = { state in
currentState = cellularData.restrictedState // This value may be inconsistent, however the next read of isRestricted should be correct.
}
}
}
}
You can detect if cellular data disabled using NWPathMonitor class. (https://developer.apple.com/documentation/network/nwpathmonitor)
let cellMonitor = NWPathMonitor(requiredInterfaceType: .cellular)
cellMonitor.pathUpdateHandler = { path in
self.isCellConnected = path.status == .satisfied
}
Adding to dirkgroten's answer, you can use the Apple Reachability class, found here:
https://developer.apple.com/Library/ios/samplecode/Reachability/Introduction/Intro.html
It uses SCNetworkReachability, and is very straight forward to use, it will detect connectivity via Cell and WiFi as you will need to check both at start up.
There are lots of frameworks out there that will give you the status of your network connectivity, and of course you can roll your own. I've found AFNetworking to be one of the best. It has a singleton class called AFNetworkReachabilityManager that abstracts some of the complexities for you. Specifically you'll want to look at the two boolean properties:
reachableViaWWAN
reachableViaWiFi
There is also a reachability changed status block that you can set:
– setReachabilityStatusChangeBlock:
AFNetworking Github
AFNetworkReachabilityManager