To get the application terminated notification I have something like the following
NSNotificationCenter* center = [[NSWorkspace sharedWorkspace] notificationCenter];
[center addObserver:self
selector:#selector(appTerminated:)
name:NSWorkspaceDidTerminateApplicationNotification
object:nil
];
- (void)appTerminated:(NSNotification *)note
{
NSLog(#"+ appTerminated");
}
actually my concern is when the firefox application quits/restarts,I need to update its database.When the firefox quits manually I can update with the help of appTerminated as firefox releasing its lock to the database.When it is running state,I am not able to update the database as firefox is locking it.when the firefox is restarted ,it is quitting and restarting too quickly so that I cannot update the database as it is in running stateI need to update database before it restarts.i.e.when the firefox is in quit state.
So,I need the notification just before firefox is going to quit.
Is any api availabe for this or please give some ideas.
Thanks in advance
I take it you have two applications, one that watches the other. Your concern seems to be that you don't want the watched app to start really doing anything until the watcher finishes its work.
You just need to communicate between the processes in this case. The watched application should wait until the watcher finishes its work. You can achieve this using a lock, or you could use NSDistributedNotification (or other IPC mechanism) to send messages from the watcher to the watched to let it know it may continue.
I prefer the locking mechanism since it behaves correctly if the watcher fails. The most correct place to put the lock would be on the database, since that's the resource you're trying to protect.
I would try something like that:
- (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender
{
if (isMyDatabaseClosed) {
[self closeMyDatabaseAndQuit];
return NSTerminateLater;
} else {
return NSTerminateNow;
}
}
-(void)closeMyDatabaseAndQuit
{
/* close your database, etc...*/
[NSApp replyToApplicationShouldTerminate: YES];
}
The code is not tested, but you should get an idea.
Related
Im developing an app on OSX that uses CoreBluetooth. I have encountered a problem on OSX Mavericks that i cant seem to get around. (All of this works perfectly on OSX 10.8).
First lets go through the flow of the application
This flow is fairly established and has been used used successfully in iOS apps and works on 10.8. So on Mavericks, the first run completes successfully. It scans, finds and connects to the device correctly. It also saves out the UUID of the device to a .plist file along with other properties.
Upon relaunch of the app, it attempts to go down the left hand column of the flow which is where the problems seem to occur.
So the first issue i noticed was that my call to self.central retrievePeripherals: never calls my delegate callback of -(void)centralManager:(CBCentralManager *)central didRetrievePeripherals:(NSArray *)peripherals
. It simply never gets the callback on Mavericks.
My next thought was "oh they have a new API for fetching peripherals on Mavericks and the old one is deprecated, lets try that". So i added in my calls to NSArray *identifiers = [self.central retrievePeripheralsWithIdentifiers:#[uuid]]; and i get caught in a sempahore wait trap. Upon closer debugging of what was going on it turned out that sometimes my CBCentralManager gets into a state of CBCentralManagerStateUnknown and never updates the state to a newer one.
The next thing i tried was to fire up Activity Monitor and kill the blued process. Finally, my delegate callback for -(void)centralManagerDidUpdateState:(CBCentralManager *)central was called with the correct CBCentralManagerStatePoweredOn so i performed retrievePeripheralsWithIdentifiers again and received an empty array.
So all of these problems seem to be linked to blued in some way. Does anyone have more insight into this process to elude as to what is going on?
My main question is. Why does this work the first time through the app but not the second? Upon quitting the app after the initial scan and connection it seems i can no longer use the system bluetooth for anything without resetting blued (which even then doesn't retrieve peripherals). Is there some sort of shutdown sequence i need to do on the CBCentralManager to keep blued from going AWOL?
Any advice would be greatly apprecciated!
While this is obviously a very old thread, I stumbled upon the same issue today and decided to post a fix for posterity.
I was trying to hack together a simple app based on the HeartRateMonitor example provided by Apple. Unfortunately, it does not work on 10.9 if autoConnect is set to TRUE, what's worse, it brings blued down on its knees.
In 10.9, a call to the (deprecated) retrievePeripherals freezes blued without a chance to restore. CBCentralManager goes into CBCentralManagerStateUnknown, Bluetooth cannot be turned on/off using OS functions etc. The only solution that I found is to killall -9 blued.
However, the synchronous retrievePeripheralsWithIdentifiers worked well for me (on 10.9.4). Here's the relevant excerpt from the modified HeartRateMonitor code:
/* Retreive already known devices */
if(autoConnect)
{
NSArray *peripherals = [manager retrievePeripheralsWithIdentifiers:[NSArray arrayWithObject:(id)aPeripheral.identifier]];
NSLog(#"Retrieved peripheral: %lu - %#", [peripherals count], peripherals);
[self stopScan];
/* If there are any known devices, automatically connect to it.*/
if([peripherals count] >=1)
{
[indicatorButton setHidden:FALSE];
[progressIndicator setHidden:FALSE];
[progressIndicator startAnimation:self];
peripheral = [peripherals objectAtIndex:0];
[peripheral retain];
[connectButton setTitle:#"Cancel"];
[manager connectPeripheral:peripheral options:[NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:CBConnectPeripheralOptionNotifyOnDisconnectionKey]];
}
}
I have been searching through the forum regarding how to check whether there is internet or not in my ipad app. I just created a simple webview project with other view controllers and I need to display a UIAlert message when the internet is not available. In my case it is displaying the message when I run the app. When I run the app with internet and then deactivate the internet, it does not show the UIAlert message, that is if I switch between the views, it does not any more show the no internet connection.
I have followed this way of implementation in my project: (sorry my mistake this is the link I followed) http://mozymac.com/forums/f54/how-check-if-there-internet-connection-iphone-os-devices-595/ [This is the new edited question]
Apart from that I went through some of the previous questions in Stackoverflow forum like for ex: How to check for an active Internet connection on iOS or OSX?
But everybody has their own version. If any one has a much more updated method for ios5, xcode 4.2.1 of how to accomplish this then would be helpful for me.
Thanks
Is there a reason why you want to check for internet connection before actually trying to load a request in the UIWebView?
Best practice is to just start loading, and use your UIWebViewDelegate/NURLConnectionDelegate to inspect the NSError to see what is wrong. In case of network failure you will receive an error with a domain equal to NSURLErrorDomain. The error code will indicate what the problem is, see the NSError codes enum.
And only after the first error start your reachability to see when the internet connection becomes available again. Or easier, just let the user retry.
Using the Reachability code will actually cause some overhead. It takes time to check if the internet is available, which you could just have used to set up the actual connection as well.
Example
Since you are using a UIWebView you should implement the following delegate method to be notified of errors.
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error {
if (![[error domain] isEqualToString:NSURLErrorDomain]) {
// not a nsurl error, take other appropriate action
return;
}
NSInteger code = [error code];
// show appropriate error to user, based on code
}
In this delegate method you should do whatever is needed to achieve what you want. You could retry the request yourself, show a message to the user or start listening for reachability changes using the code from the Reachability example provided by Apple.
Apple has one, it's called Reachability. Here's the link to it.
http://developer.apple.com/library/ios/ipad/#samplecode/Reachability/Introduction/Intro.html
Best way to check internet connection is Reachibility application
link
Or else
+ (BOOL)isNetworkAvailable
{
CFNetDiagnosticRef diag;
diag = CFNetDiagnosticCreateWithURL (NULL, (CFURLRef)[NSURL URLWithString:#"www.apple.com"]);
CFNetDiagnosticStatus status;
status = CFNetDiagnosticCopyNetworkStatusPassively (diag, NULL);
CFRelease (diag);
if ( status == kCFNetDiagnosticConnectionUp )
{
//NSLog (#"Connection is up");
return YES;
} else {
NSLog (#"Connection is down");
return NO;
}
}
I have a mac app that writes camera data to a file then uploads that file on an [NSTimer] to a server. However, after the camera runs for a while it closes itself and I see this in the log: * QTCaptureDeviceInput warning: The device "FaceTime HD Camera (Built-in)" was closed while still being used in a capture session. Make sure that the session is not running before closing any devices it is using.
No other apps are open that can use the camera in the test case and the object for the device is not being released by me. I have gone so far as to call retain on it to prevent this, to no avail.
I looked at Apple's docs and nowhere that I found did it talk about the camera being shut off by the system, so what could be causing this. In the meantime I have some code that periodically checks if it is open and if it isn't calls open on it.
One thing I forgot I am using this notification and it is being fired: QTCaptureDeviceWasDisconnectedNotification
Well, it took a while but I found the issue. When you you are pulling image data from a running QTCaptureDevice you need to work with individual frames via the following delegate method. If you fail to properly release the buffers on each run the camera will eventually close by itself. Please note the code below is CORRECt; I attached it to help anyone else reading this question. Hope this saves someone the time it costed me...
- (void) captureOutput:(QTCaptureOutput *)captureOutput didOutputVideoFrame:(CVImageBufferRef)videoFrame withSampleBuffer:(QTSampleBuffer *)sampleBuffer fromConnection:(QTCaptureConnection *)connection {
CVBufferRef bufferToBeReleased;
CVBufferRetain(videoFrame);
#synchronized (self) {
imageBufferToRelease = imageIWanted;
imageIWanted = videoFrame;
}
CVBufferRelease(bufferToBeReleased);
}
I have read
this question and found its answer to be useful to check an internet connection for the iPhone. I implemented the check in my viewDidLoad message.
However my App does load Data from an XML file from a server (within viewWillAppear). In this case the check has to be done before the app tries to load the data from the internet source. My problem here is that the network check requires some seconds but the app does proceed with the code.
This results in delaying the check. So there is a valid internet connection, but the bool variable that stores this information is set too late.
Code in viewDidLoad
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(checkNetworkStatus:) name:kReachabilityChangedNotification object:nil];
internetReachable = [[Reachability reachabilityForInternetConnection] retain];
[internetReachable startNotifier];
The selected message is implemented in the same way like in the example in the link above. Additionally it sets some bool-properties so I can access the connection state within the app.
Code in viewWillAppear
if(internetActive == TRUE)
{
NSLog(#"connected");
//Code to load XML stuff
}
else
{
NSLog(#"not connected");
}
The console shows me "not connected". But a few seconds later the debug logs within "checkNetworkStatus" show me that the internet connection is available and the bool "internetActive" would be set.
I assume that the network check delivers his report about the connection state too late for my purpose. Is there a way to delay the app until the connection is established? Or would this lead to crashing the app cause the view isn't displayed within a few seconds?
Are there any other possibilities to ensure the connection?
My second question is how to ensure a specific internet address is available? I the link above there is mentioned
hostReachable = [[Reachability reachabilityWithHostName: #"www.apple.com"] retain];
[hostReachable startNotifier];
to detect the connection to a host, but I want to go in detail and try to detect if the host deserves a specific address or not. But entering the full address path (e.g. "localaddress.mylan.de/lan/xml/") instead of the host leads to a not reachable connection state for the host. Entering the mentioned address in the browser address bar shows me the correct result. I guess I have to check it otherwise but how?
Thanks for reading :)
After getting more experiences with IOS development my first question is solved with three steps.
First step is to start all necessary notifiers once. This can be done by starting them in viewDidLoad of the first loaded ViewController.
Check current connection state by evaluating property named currentReachabilityStatus of reachability-objects. This state can be "not connected" even if a connection is available. This happens if the check is done within the ViewController who is starting the notifier. Reason for this is the time it takes while the notifier recognizes the connection. If currentReachabilityStatus property is evaluated as connected then data loading processes can be started.
Evaluating the connection state within the method whose selector is added during adding the notifier. This method will start every time the connection state changes. First call will be directly after starting the notifier. If connection state is evaluated as connected then data loading processes can be started.
The second question stays unresolved up to now. May be there is no way other than sending a request to the target and waiting for a response or a timeout.
Did you try dispatch_async & dispatch_sync(dispatch_get_main_queue( reload data here ) ?
Sorry to bug twice so quickly, but since people were so kind in their informative responces, I figured it couldnt hurt to ask another question.
The same program i tried to make it rather swanky and have a main screen which allows you to click on a button which leads to a limited options screen. This lets you switch the music on or off. Or at least it should do.
The music running code is in the main file (game.m), under the following:
//Music
[Settings setMusicEnabled:YES];
music = [SPSound soundWithContentsOfFile:#"music.caf"];
channel = [[music createChannel] retain];
channel.loop = YES;
channel.volume = 0.25;
if([Settings musicEnabled]){
[channel play];
}
I apologize for the strange format, but it is Sparrow framework. basically, the Settings file contains the class methods I am trying to use. If the methods cause YES, the music is on. If it is No, then the music is off.
settings.m
static BOOL isMusicEnabled;
#implementation Settings
+ (BOOL)musicEnabled
{
return isMusicEnabled;
}
+ (void)setMusicEnabled:(BOOL)value
{
isMusicEnabled = value;
NSLog(#"SME? %i", isMusicEnabled);
}
#end
Now, the options file is working and i tested that section. The program is reading that isMusicEnabled is getting a new value, thus musicEnabled is being altered as well, so there should be a change and the music should be switched off.
However, nothing happens. I have tried to use debugger, but I am not very good at it and I dont understand a lot of the information i am given. I do understand that the problem is sending the message from Settings file to the main/Game file.
I would appriciate anyone's help who could enlighten me as to how this could be solved.
I'm not familiar with Sparrow Framework, but let me make a guess anyway.
[channel play]; starts playing the music in background until the channel is asked to stop playing.
Changing the isMusicEnabled does not trigger any code to stop the currently playing music. When you change the value in Settings, you should inform the channel to stop (most probably by somehow accessing the channel and calling [channel stop].
There's another problem - isMusicEnabled is just a variable in memory, your program will not remember its state between restarts. And Settings are usually supposed to be remembered.
To summarize I see two problems: persisting settings between restarts first and informing about change of settings second. To remember settings I suggest you look into NSUserDefaults class. To inform the channel to stop playing you have couple of options - depending on you skills. Easiest is to simply access the channel variable from within the setMusicEnabled and call stop. Another option would be to use notifications, but for a beginner programmer that is more complicated (look for NSNotificationCenter if interested).