Subclassing UIApplication to override sendEvent causes crash - iphone

Question

I'm trying subclass UIApplication to catch all touch event, this is used to see if user is afk or not. Anyway it works great first time you launch the application. If you put it in background and open it again 2 times then it crashes. I have no idea what causes this. I'm getting EXEC_BAD_ACCESS on [super sendEvent:event];
My Subclass MyUI:
#implementation MyUI
- (void)sendEvent:(UIEvent *)event {
[super sendEvent:event]; // <-- EXEC_BAD_ACCESS
if (event.type == UIEventTypeTouches) {
UITouch *touch = [event allTouches].anyObject;
if (touch.phase == UITouchPhaseBegan) {
// Calling some methods
}
}
}
#end
Main.m
int main(int argc, char *argv[])
{
NSString* appClass = #"MyUI";
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
int retVal = UIApplicationMain(argc, argv, appClass, nil);
[pool release];
return retVal;
}

Answer 1

Is there a reason the super class method is being called first? If you are intercepting, you should be calling it last.
That might be your problem. I also override sendEvent to intercept all events to my application and have no issues.
If you call the super method first it will pass it to all UIResponders that may eventually eat your event resulting in the EXEC_BAD_ACCESS. Furthermore as DavidNeiss suggests eliminate the lines below the super call. If you still receive the bad access signal its likely another view or controller down the line causing it. You'll need to stack trace to find out where it is.

Answer 2

To get exact reason for EXEC_BAD_ACCESS use nszombieenabled in your application.
This link will guide you for using it.
http://iosdevelopertips.com/debugging/tracking-down-exc_bad_access-errors-with-nszombieenabled.html

Answer 3

Dont understand what "afk" means.
Another approach might be to create a custom gesture recognizer. They (gesture recognizers) are supposed to filter through touch events before they are forwarded to the view as part of the normal touches event processing.

Answer 4

Just for simplicity's sake, I would put the #"MyUI" directly into the UIApplicationMain call.
The string is most likely your problem. It's outside of the NSAutoreleasePool, and that is just not done.
In addition, the name #"MyUI" hints at a view controller, not an AppDelegate class. Look into that.

Answer 5

[super sendEvent:event]; // <-- EXEC_BAD_ACCESS
means error is in your class.
For testing block
/*
- (void)sendEvent:(UIEvent *)event {
[super sendEvent:event]; // <-- EXEC_BAD_ACCESS
if (event.type == UIEventTypeTouches) {
UITouch *touch = [event allTouches].anyObject;
if (touch.phase == UITouchPhaseBegan) {
// Calling some methods
}
}
}
*/
still you will get that error. Any time if you are getting error while override sendEvent
try to block all override method and check still you are getting that error or not specially for this line [super sendEvent:event];. I had also stuck with this error and figured out no mistake in this method. Mistake was found in applicationDidFinishLaunching. Always keep your code within try catch method
#try {
}
#catch (NSException *exception) {
NSLog(#"Exception => %#",exception);
}
This will help you figure out right problem.