调试Iphone程序收到信号：“ EXC_BAD_ACCESS”

Question

i searched and tried a lot. But i really have no idea how to solve this – Thanks for your help

The Error-MSG:

Program received signal:  “EXC_BAD_ACCESS”.

The Line throwing the MSG

log(sos_Trace, @"sendMail");

---

Important

I make use of this logging-lib: http://code.google.com/p/soslog-objc/

Full SourceFile

#import "ContactViewController.h"
#import "SOSLog.h"

@implementation ContactViewController

@synthesize mailButton, delegate;

- (void)viewDidLoad {  
    self.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"bg_tile.gif"]];  
    [super viewDidLoad];  
}  

- (IBAction)sendMail:(id)sender {
    NSLog(@"sendMail");
    log(sos_Trace, @"sendMail");

    [delegate mail:self];
}

- (void)dealloc {
    [self.mailButton release];
    self.delegate = nil;
    [super dealloc];
}

@end

Answer 1

Having a look at the source for the SOS logging framework, log(sos_Trace, @"sendMail"); cannot possibly be the source of the crash unless you have code elsewhere that is corrupting the internals of the logging infrastructure.

Post the full stacktrace of the crash.

As @benzado noted, you have some bugs in your memory management code. Fix those, too. I would suggest running the static analyzer over your code and fixing anything it finds. shift-cmd-A in Xcode should do the trick.

Also, if you want to log when a method is called, this will work in any method :

log(sos_Trace, NSStringFromSelector(_cmd));

Or:

NSLog(@"[%@ %@] -- your message here", NSStringFromClass([self class]), NSStringFromSelector(_cmd));

Answer 2

I've not used the soslog framework before, so I can't offer any insight there. However, EXC_BAD_ACCESS is frequently caused by trying to access an object that's either been dealloc'd, or never initialized to begin with. Has sos_Trace been set up before you call it?

Answer 3

EXC_BAD_ACCESS means you are trying to access memory at an invalid address. It usually happens when you try to use a pointer that hasn't been initialized and is pointing to some random location in memory.

I don't know anything about that logging library, but I would guess is that there is some setup or initialization function that you need to call. Looking at the website it doesn't seem like there is, though.

---

One other thing that sticks out, though is probably not related, is the line

[self.mailButton release];

in your dealloc method. It's probably not a problem since it is in your dealloc method, but if you're going to use a property accessor you should leave the retain and release to it. If you had that line in any other place, you'd cause a EXC_BAD_ACCESS later if the mailButton property was reassigned. That's because:

self.mailButton = THING; // retain count +1
[self.mailButton release]; // retain count -1
self.mailButton = OTHER; // EXC_BAD_ACCESS!

That's because the third line is really a call to setMailButton: , which internally calls [THING release] , but since you already released it, you have now unbalanced your retain/release calls and so either then or later (if somebody else has retained it) release will be called on an invalid object and your program goes kablooey.

Answer 4

Fixed the bug. The socket was dealloced due to a missing retain.