EXC_BAD_ACCESS error in Objective-C - ios

Question

I'm trying to write a simple iOS program that will notify when headphones are plugged/unplugged. I'm very new to Objective-C and iOS, and a lot of this code was written by somebody else and I'm now trying to adapt it so I'm having issues figuring out this problem. The code is here:
AppDelegate.m
#import "AppDelegate.h"
#implementation AppDelegate
static void onHeadsetChange(void *, AudioServicesPropertyID, UInt32, const void *);
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.headsetOnHandler = self.headsetOffHandler = ^{};
NSLog(#"%lu", AudioSessionInitialize(NULL, NULL, NULL, NULL));
NSLog(#"%lu", AudioSessionSetActive(true));
NSLog(#"%lu", AudioSessionAddPropertyListener(kAudioSessionProperty_AudioRouteChange, &onHeadsetChange, (__bridge void *)self));
return YES;
}
static void onHeadsetChange(void *inUserData, AudioSessionPropertyID inPropertyID, UInt32 inPropertyValueSize, const void *inPropertyValue) {
if (inPropertyID != kAudioSessionProperty_AudioRouteChange) return;
NSLog(#"The headset changed");
AppDelegate *const delegate = (__bridge AppDelegate *)inUserData;
const CFDictionaryRef routeChangeDictionary = inPropertyValue;
const CFNumberRef routeChangeReasonRef = CFDictionaryGetValue(routeChangeDictionary, CFSTR(kAudioSession_AudioRouteChangeKey_Reason));
SInt32 routeChangeReason;
CFNumberGetValue(routeChangeReasonRef, kCFNumberSInt32Type, &routeChangeReason);
switch (routeChangeReason) {
case kAudioSessionRouteChangeReason_NewDeviceAvailable:
//NSLog([delegate description]);
[delegate headsetOnHandler];
break;
case kAudioSessionRouteChangeReason_OldDeviceUnavailable:
[delegate headsetOffHandler];
break;
default:
break;
}
}
#end
ViewController.m
#import "ViewController.h"
#implementation ViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.view.backgroundColor = [UIColor redColor];
AppDelegate *delegate = (AppDelegate *)([UIApplication sharedApplication].delegate);
delegate.headsetOnHandler = ^{ self.view.backgroundColor = [UIColor greenColor];};
delegate.headsetOffHandler = ^{ self.view.backgroundColor = [UIColor redColor];};
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
I'm getting the EXC_BAD_ACCESS error, code=1 at [delegate headsetOnHandler] and [delegate headsetOffHandler]. If I need to include the .h files for this to make sense, I will, and if there's anything else I'm missing please let me know.
EDIT:
I've added in declarations that people thought should be added:
#property (readwrite, assign) void (^headsetOnHandler)(void);
#property (readwrite, assign) void (^headsetOffHandler)(void);

Answer 1

How is the headsetOnHandler and headsetOffHandler properties declared?
If it is assign or retain, that is likely the source of your problem. Since they are blocks, it needs to be copy (even, in certain cases, under ARC). If they are atomic and retain, then your getter will call, effectively, [[block retain] autorelease] in the getter, which would explain your crash.
A bit of a long shot.
when you have a crash, always post the backtrace
when you know the line of code the crash is on, always post the variable declarations of any variables on that line
Note that ARC will change this behavior a bit, automatically handling the blocks in some cases, but -- IIRC -- you would still need to copy them in this case.