How to handle UIApplicationWillTerminateNotification in IOS4?

1

In iOS4 I'm registering the following notification:

[[NSNotificationCenter defaultCenter]   addObserver:self
                                                 selector:@selector(appWillTerminate:)
                                                 name:UIApplicationWillTerminateNotification
                                                 object:[UIApplication sharedApplication]];

-(void)appWillTerminate:(UIApplication *) app {
    NSLog(@"terminate");
}

I know that this is not called in all the situations like in the prev iOS versions, however, simply by registering this I get a EXC_BAD_ACCESSS when the app exits. Still, I can't remove it because my app supports iOS3.0+. How can I handle this?

UPDATE: Here is the crash log:

Exception Type:  EXC_BAD_ACCESS (SIGBUS)
Exception Codes: KERN_PROTECTION_FAILURE at 0x00000011
Crashed Thread:  0

Thread 0 Crashed:
0   libobjc.A.dylib                 0x0000441c objc_msgSend + 20
1   Foundation                      0x00015432 _nsnote_callback + 150
2   CoreFoundation                  0x000271da __CFXNotificationPost_old + 390
3   CoreFoundation                  0x00026e7a _CFXNotificationPostNotification + 122
4   Foundation                      0x00004720 -[NSNotificationCenter postNotificationName:object:userInfo:] + 64
5   Foundation                      0x0000de3a -[NSNotificationCenter postNotificationName:object:] + 14
6   UIKit                           0x000bef10 -[UIApplication _terminateWithStatus:] + 164
7   UIKit                           0x000be1b0 -[UIApplication _handleApplicationSuspend:eventInfo:] + 1980
8   UIKit                           0x0007e4a0 -[UIApplication handleEvent:withNewEvent:] + 3620
9   UIKit                           0x0007d470 -[UIApplication sendEvent:] + 60
10  UIKit                           0x0007ccf8 _UIApplicationHandleEvent + 6804
11  GraphicsServices                0x00005dd8 PurpleEventCallback + 1024
12  CoreFoundation                  0x00035e40 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 22
13  CoreFoundation                  0x00035dfe __CFRunLoopDoSource1 + 158
14  CoreFoundation                  0x0002809e __CFRunLoopRun + 574
15  CoreFoundation                  0x00027d74 CFRunLoopRunSpecific + 220
16  CoreFoundation                  0x00027c82 CFRunLoopRunInMode + 54
17  GraphicsServices                0x00004e84 GSEventRunModal + 188
18  UIKit                           0x00004f8c -[UIApplication _run] + 564
19  UIKit                           0x000024cc UIApplicationMain + 964
iphone
objective-c
ipad
ios4
nsnotificationcenter
asked on Stack Overflow Jun 28, 2011 by Valentin Radu • edited Jun 28, 2011 by Valentin Radu

3 Answers

1

Make sure that you remove the observer in any class that is listening for the terminate notification. If you are not removing the notification it will try to post it to a deallocated object and then your application will crash. You should not be crashing for listening to a notification that does not exist, it just would not get called.

//YourClass
-(id)init
{
    if((self = [super init]))
    {
        [[NSNotificationCenter defaultCenter]   addObserver:self
                                             selector:@selector(appWillTerminate:)
                                             name:UIApplicationWillResignActiveNotification
                                             object:[UIApplication sharedApplication]];
    }
    return self;
}

-(void)appWillTerminate:(NSNotification *)note {
    NSLog(@"terminate");
}

-(void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];

    //Other releases
    [super dealloc];
}
answered on Stack Overflow Jun 28, 2011 by Joe • edited Jun 28, 2011 by Joe
0

What you could do is detect the iOS version, and if its v. 3.0 then use appWillTerminate and if its v. 4.0 use appWillResignActive or appDidEnterBackground, example:

NSString *ver = [[UIDevice currentDevice] systemVersion];
if([ver isEqualToString:@"3.0"]){
    //Device is running 3.0
    [[NSNotificationCenter defaultCenter]   addObserver:self
                                             selector:@selector(appWillTerminate:)
                                             name:UIApplicationWillTerminateNotification
                                             object:[UIApplication sharedApplication]];
}
else if([ver isEqualToString:@"4.0"]){
    //4.0
    [[NSNotificationCenter defaultCenter]   addObserver:self
                                             selector:@selector(appWillTerminate:)
                                             name:UIApplicationWillResignActiveNotification
                                             object:[UIApplication sharedApplication]];
}
answered on Stack Overflow Jun 28, 2011 by Chance Hudson • edited Jun 28, 2011 by Chance Hudson
0

The first argument passed to your appWillTerminate: method will be an NSNotification object, not your UIApplication. See the NSNotificationCenter Class Reference

answered on Stack Overflow Jun 28, 2011 by Jim • edited Jun 28, 2011 by Jim

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