i got this piece of code:
- (void)postToWall {
FBStreamDialog *dialog = [[FBStreamDialog alloc] init];
dialog.userMessagePrompt = #"Un tuo commento:";
dialog.attachment = [NSString stringWithFormat:#"{\"name\":\"Bla: %#\"", facebookName];
[dialog show];
[dialog release];
}
the first time it get executed it works fine, no problem. But if I post or skip and then I post again I got an EXC_BAD_ACCESS, due to facebookName. The console shows no error, I found it via DebugConsole. I really don't know why this happens, can someone help?
EDIT: SOLVED!!!
In other parts of the code, I accessed the facebookName string by its name. This apparently leads to crash, so I synthesized it and then accessed it by "self.facebookName".
Thank you.
You should show contextual code regarding facebookName.
I think maybe it is being released by the time you use it again. Just to be safe, you can try doing [facebookName retain] at the beginning of the method and then [facebookName release] at the end, to signify that you need to hold on to the object to do some work.
Yep, using the synthesized property automatically retains objects when you assign them (provided you have the usual, (nonatomic, retain)). Before, it wasn't retaining so by the time you used it again a couple times, you would get EXC_BAD_ACCESS since it no longer existed (was released by then, cause again, it wasn't retained).
You will likely not get a valid stack trace at the time of the crash.
The quickest way to track down the real cause of EXC_BAD_ACCESS is by using the NSZombieEnabled executable argument, and then setting a breakpoint on objc_exception_throw. This will get you a stack trace, and allow you to determine specifically which object you are trying to access.
http://www.cocoadev.com/index.pl?NSZombieEnabled
Using Malloc to debug
Related
I am new in iOS. I want to use iToast in my App. I followed toast-notifications-ios
First when I created my iToast.m I got four errors on these lines:
[label release];
[imageView release];
view = [v retain];
iToast *toast = [[[iToast alloc] initWithText:_text] autorelease];
I always have problem with release and autorelease in different examples. I use iOS 5.1, xCode 4.3.3. I saw many examples using them but I always got errors on them. Can you let me know why?
When I commented the first third error lines and use the forth one like:
iToast *toast = [[iToast alloc] initWithText:_text];
I could run the project but when the Toast pops up, it never disappears. I used this line as written in README.md:
[[[[iToast makeText:NSLocalizedString(#"Something to display a very long time", #"")]
setGravity:iToastGravityBottom] setDuration:iToastDurationShort] show];
How can I solve this problem?
If you just started out you are probably using Automatic Reference Counting, or ARC. Using this the compiler handles the memory for you and renders retain, release,and autorelease for you. You can either disable ARC for your project or go through the supplied code and make it ARC compliant by translating retains, releases, and autoreleases.
This explains the differences and how to transition:
http://developer.apple.com/library/ios/#releasenotes/ObjectiveC/RN-TransitioningToARC/Introduction/Introduction.html
I've got a fairly simple app that has the following in the view the program is mostly in:
int currentPageIndex;
NSArray *images;
NSString *nextImage;
IBOutlet UIImageView *firstPage;
IBOutlet UIButton *bigButton;
In the implementation viewDidLoad, I load the array with a bunch of image file names:
images = [NSArray arrayWithObjects:#"image1.jpg", #"image2.jpg", etc, nil];
[images retain];
Each time the bigButton is tapped, the image changes:
- (IBAction)bigButtonTapped:(id)sender {
currentPageIndex++;
nextImage = [images objectAtIndex:currentPageIndex];
firstPage.image = [UIImage imageNamed:nextImage];
}
Everything works as I want it to, except that I am getting a "Received memory warning. Level=1" in the console with my device plugged in. This warning comes up after every 12 images or so, and eventually it crashes with "EXC_BAD_ACCESS"
I thought this would actually be a good way not to put anything in memory, as there is only one UIImageView on the screen and its image is changed as I need it to be.
It is a very simple app so I'm sure the fix is very simple... any ideas what I might be overlooking? Thanks so much!!
Since you get a memory warning, the problem must be that the images aren't released. However, in the code you show, you're handling the images correctly. So the problem is most likely in a part of the code you're not showing us.
The only minor problem is see, which has been mentioned before, is that the currentPageIndex will eventually point outside of the range of the array. But this will cause a different error.
To avoid going over the size of the Array,
currentPageIndex= 0;
for(currentPageIndex in images){
doStuff;
}
OH!!!!! I THINK I spotted the your problem. Whenever you use UIImage imageNamed to load images all the images stay in memmory even though release reference to it. use the other UIImage method:contentOfFile.
One other thing, make sure your images are optimize for iOS. Use .png when posibible.
dibu2z
I assume Image is a retained property.
Try to release it at the beginning of your bigButtonTapped.
Hope it helps.
Could be that you've reached the end of the array and you're trying to access past the end of the array. You could do a
currentPageIndex++;
if ( currentPageIndex < [images count]) {
nextImage = [images objectAtIndex:currentPageIndex];
firstPage.image = [UIImage imageNamed:nextImage];
}
Also could be that the image you listed doesn't exist in the bundle.
There isn't really enough information here to say for sure what your problem is. EXC_BAD_ACCESS generally happens when you try to access an objects that has already been deallocated.
The quickest way to track down the real cause of EXC_BAD_ACCESS is by using the NSZombieEnabled executable argument, and then setting a breakpoint on objc_exception_throw. This will get you a stack trace, and allow you to determine specifically which object you are trying to access.
http://www.cocoadev.com/index.pl?NSZombieEnabled
Using Malloc to debug
I'm experiencing a wierd behavior in the new AVFoundation classes in the iPhone SDK.
I have a AVCaptureStillImageOutput for taking pictures, and I am setting its outputSettings to my liking. The code follows:
AVCaptureStillImageOutput *stillImageOutput = [[[AVCaptureStillImageOutput alloc] init] autorelease];
[stillImageOutput setOutputSettings:[NSDictionary dictionaryWithObject:AVVideoCodecJPEG forKey:AVVideoCodecKey]];
[self setStillImageOutput:stillImageOutput];
(stillImageOutput property is defined as "retain")
I stumbled upon a leak in leaks, with 100% of the leak fault on the setOutputSettings line. I believe that I confine to the memory management guidelines in the code attached, still it is leaking.
My solution was to
[self.stillImageOutput setOutputSettings:nil];
in the dealloc, just before
[self setStillImageOutput:nil];
The leak indeed stopped, but it looks weird. Shouldn't the releasing of stillImageOutput release its outputSettings property as well?
Anyway, if someone else runs into this, thought I should share my solution.
Cheers!
Oded.
Yes, the releasing of stillImageOutput should release it's outputSettings property as well. Either it's an Apple bug (should let them know, your use case is pretty simple) or remove your line, and see whether anything other than your class is hanging onto that stillImageOutput object (which is holding the outputSettings).
I'm getting a EXC_BAD _ACCESS after leaving the method below. At that point htmlDocument becomes invalid, which it should since it falls out of scope. But is that why I'm getting the error? By the time the contentView (UIWebView) loads, htmlDocument is gone. But doesn't contentView already have what it needs from loadHTMLString?
- (void)viewDidLoad {
[super viewDidLoad];
//something other processing here
NSString *htmlDocument = [NSString stringWithFormat:#"<html> \n"
"<body>%#</body> \n"
"</html>", aboutContent];
[contentView loadHTMLString:htmlDocument baseURL:[NSURL URLWithString:#"http://www.abc.com"]];
}
Is there a better way to follow this all the way to failure? Leaving this method is the end of the line for my code. SDK stuff from there.
From your second post, the line you have commented out ([button release]) releases an object already marked to be released automatically.
Either remove the "autorelease" where you are doing an alloc for the button or remove the [button release] statement for the code to compile without errors and exceptions.
If an object is marked for autorelease, calling a release on it will be the same as calling a release on a deallocated instance, hence the error.
At a glance I would say there is nothing wrong with this code, assuming 'aboutContent' is a valid pointer to an object.
You can try running your app with Guard Malloc on the simulator, but that's not guaranteed to turn up anything. I'd suggest you just start commenting out statements until you find the one that's causing the error.
It's not clear what's going on with the code snippet you've just provided without more context. That said, it looks like all you want to do is load some HTML locally in the device. Why not just do this?
- (void)viewDidLoad {
[webView loadRequest:[NSURLRequest
requestWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle]
pathForResource:#"help/about.html"
ofType:#"html"]isDirectory:NO]]];
}
Using this technique, you can author HTML-based documents right in your phone without the user being wise to the fact that they are actually looking at a web view: this includes Javascript, CSS, the whole ball of a wax. I've seen people actually have their iPhone app go out to the Internet just to render a static page on the Internet which really is not necessary.
From your sample code in the second post, the button you release UIBarButtonItem *button is not retained by anything following the release you have commented out - and so it is deallocated.
You need to add the button to another view (using adSubview) in order for it to display and then you can release it. The parent view will retain the button.
Of course if you are going to refer to the button again, your view controller should keep the retain and release the button in its dealloc.
I'm getting memory leak with UIImagePickerController class.
Here's how I'm using it:
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
[self presentModalViewController:picker animated:YES];
[picker release];
To remove the picker i call [picker dismissModalViewControllerAnimated:YES]; in didFinishPickingImage and imagePickerControllerDidCancel.
--
Instruments show around 160bytes leaking as a result of this instruction:
+[UIImagePickerController _loadPhotoLibraryIfNecessary]
Apparently this issue has and is disturbing many people, and solution
to avoid this problem is to build a
singleton class dedicated for picking
images from library or capturing using
device's build in camera.
Anyone want to add something?
As the author of one of the first articles about the necessity to use a singleton, the motivation was to prevent a crash on the 7/8th image capture, not because of any particular worry about the leak. 160 bytes is annoying, but not a major problem, and therefore not worth worrying about (because it can't be fixed by developers).
Have you tried deleting the delegate line? I’ve had similar problems with AVAudioPlayer when delegating to self. (Even though the accessor says assign in both cases.) If the leak goes away with the delegation, you can delegate to a different object.
I was having a memory alloc leak which I found in Instruments.
All I was doing was opening and closing the image picker (open/cancel) and using Apple code, my code and other people's code.
All were showing the allocation going up and up each time, as if the picker was not being released.
If you tried to release it, it would crash (over released).
Then I found a really helpful web page which basically stated:
"This doesn't happen when testing on the device"
So I switched from the simulator and ran the tests on the device.
Lo & behold there was no allocation increase and it behaved normally.
This however is totally evil and now we can place no trust in the simulator to do a reliable job. Whether this is pertinent to your specific problem or not, I took you up on anything else to add, and my thing to add is don't test memory on the simulator!
The reason maybe that you forget to release image. Because each time you write
UIImageView.image = image_a;
Then , image_a will get retained once.
Until you let UIImageView.image = nil, when image_a can be release finally.
I resolved my problem in this way.
If you see memory leaks several GeneralBlock and SegmentMachO by using UIImagePickerController,
Try by adding CoreLocation framework and MapKit framework to your project. I don't see anymore memory leaks in the instrument tool leak checking. I don't know how UIImagePickerController related to these frameworks. I am not sure it is good solution or not. "adding frameworks without using or necessary".
I have also got the memory leak by using UIImagePickerController. That memory leak happen even in the sample code "PhotoLocation" and "iPhoneCoreDataRecipes" downloaded from developer.apple.com. I also checked by adding these frameworks to those downloaded sample code. There is no memory leaks anymore.