UIAlertView Button action causing error - ios

Question

I am displaying a UIAlertView to the user with an "OK" button on it, and when the user presses the button I would like my delegate method to perform an action. However currently when the user presses the "OK" button the application crashes with this error:
Thread 1: EXC_BAD_ACCESS (code=1, address=0xb)
Here is my code, the alert view shows fine with the button etc, however as soon as the button is pressed this is the error I am getting. It's almost like a breakpoint but if I click the forward button nothing happens.
//.h
#interface ErrorHandling : NSObject <UIAlertViewDelegate> {
//.m
#define myAlertViewsTag 0
- (void)recivedErrorCode:(int)errorCode MethodName:(NSString *)methodName {
switch (errorCode) {
case 1: {
NSLog(#"ERROR = 1");
message = [[UIAlertView alloc] initWithTitle:#"Error 1:"
message:#"The supplied registration code does exist."
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[SVProgressHUD dismiss];
[message show];
}
break;
case 2: {
NSLog(#"ERROR = 2");
message = [[UIAlertView alloc] initWithTitle:#"Error 2:"
message:#"Your registration is no longer valid."
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
message.tag = myAlertViewsTag;
[SVProgressHUD dismiss];
[message show];
}
break;
default:
break;
}
}
-(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex {
if (message.tag == myAlertViewsTag) {
if (buttonIndex == 0) {
// Do something when ok pressed
NSLog(#"DONE 1");
} else {
// Do something for ok
NSLog(#"DONE 2");
}
} else {
// Do something with responses from other alertViews
NSLog(#"DONE 3");
}
}
update:
This is how I call the class the code above is in from my conneciton class.
// Do whatever you need to with the error number
ErrorHandling *errorHandling = [[ErrorHandling alloc] init];
[errorHandling recivedErrorCode:errorRecivedFromServerInt MethodName:methodName];

Answer 1

The problem is with the lifetime of your ErrorHandling instance. You create an instance and then call the recivedErrorCode: method. After that there are no other strong references to your errorHandling instance so it gets deallocated.
Meanwhile the alert view has made the instance its delegate. When you tap the button on the alert view, the alert view tries to contact its delegate. But the delegate has been deallocated and now points to garbage memory resulting in the crash.
The solution is to keep a longer lasting strong reference to the ErrorHandling instance. At least until after the alert view is dismissed.
BTW - Your method name has a typo - it should be receivedErrorCode:.

Answer 2

It is not at all clear from this code if this line:
if (message.tag == myAlertViewsTag)...
Actually points to anything valid. Is the message object still around even... I think you problems lies there, somewhere. Post more code that helps us understand this if you want more help.

Answer 3

In alertView:didDismissWithButtonIndex: you are checking the alert view's tag by using "message.tag".
It looks like you were intending for message to be an ivar in your class. A better way that should also solve your bad_access would be to use the alert view that is passed into the didDismissWithButtonIndex, rather than retaining the UIAlertView in your class. This code should do the trick:
-(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex {
if (alertView.tag == myAlertViewsTag) {
if (buttonIndex == 0) {
// Do something when ok pressed
NSLog(#"DONE 1");
} else {
// Do something for ok
NSLog(#"DONE 2");
}
} else {
// Do something with responses from other alertViews
NSLog(#"DONE 3");
}
}