Ok I use arc in my main application but have ported a control which does not use arc .. every thing compiles etc but I get EXC_BAD_ACCESS error on the controls event ...
The event is initiated from Delegate Method
Is there a way to get the pointers text value from the hex code value i.e Name* from the 0X00AA0 address ?
And what is the standard way of checking what arc is deallocating?
Is there a way to get the pointers text value from the hex code value i.e Name* from the 0X00AA0 address ?
Try to play around with llvm debugger. After something crashes or at your breakpoint use something like this:
expression 0x00aa0
Related
I want to create a breakpoint in xCode which uses LLDB and checks the current object class in condition section.
The problem is LLDB doesn't allow to use self to get a class. How to solve this problem? Maybe through other commands? For example, bt command output contains correct classname but it seems it is not allowed in LLDB too.
I presume this is related to:
Using of symbolic breakpoints for child classes in Xcode?
The problem comes if your breakpoint is in code with no debug information (like in system libraries.) The debugger knows nothing about self in this context, and you have to give it more help. In the case of self, you know that it was passed into a method call as the first argument, so you can use $arg1 to get at the value.
Is it possible to access the properties of objects in xCode console?
If I try the following I get an error that he property doesn't exist.
po someObject.someprop
If I don't breakpoint the code and run the app it works fine so I know someObject.someprop exists. I don't think I have the grasp on xCode console yet? What I loved about Flex/Flash development is that I could set a break point and in the console window or variables view I could traverse every structure down to the ends of the earth.
I could see SomeDicionary[key].someArray[1].someObject.prop and it would show me the value. Is this not possible in xCode console or is there a trick to get to it?
You'll actually have to use the bracket syntax notation:
po [someObject someprop]
The debugger is sometimes very finnicky about syntax. This is filled with all sorts of helpful tips for debugging in XCode.
Just a side note, variables/properties declared in the implementation file (*.m) instead of the header file (*.h) can sometimes be invisible to the debugger variable list display depending on if the breakpoint is in that class's code, because of scope. Not necessarily required here, but useful to know seeing as how it is kind of relevant.
I'd like to move from NSLogging all over the place to using breakpoints for logging where the performance hit doesn't preclude it.
I know I can just po an object with a Debugger Command action, and I know I can just log any string by choosign the Log Message action.
And I think I should be able to combine both by choosing Log Message and entering something like SomeText giving context for object description: #(const char *)[[anObject description] UTF8String]#. Unfortunately, this doesn't seem to work, and always gives me what I assume to be the pointer to the description string.
What am I doing wrong?
It's kinda tricky but I think that this will work. Set the breakpoint Action as a debugger command. Then use this text as the action:
po (NSString *) [#"Some text describing: " stringByAppendingString:(NSString *)[anObject description]]
You must always be very careful to cast return types when working in the debugger. Both with GDB and LLDB.
I like your idea of using breakpoints to avoid the performance hit, but this also means that your logs will only be printed when connected to a debugger. While NSLogs will buffer their output to the system log, viewable from the Organizer (Devices) in Xcode.
(Edit: I missed the question's point and it's not an answer)
I think it's best to use DebugLog. It's a macro, and you can disable it easily (it's on when you def-ine DEBUG in your debug builds and is off when you don't define it). So, there's no performance degradation (quite the contrary).
Simply replace
NSLog(#"Hello, World!");
with
DebugLog(#"Hello, World!");
And instead of
19/4/12 8:55:52.949 PM Dictionary: Hello, World!
You'll get:
BetterDictionary.m:737 Hello, World!
(it shows which file and even which line has logged it)
Which is infinitely more interesting. undefine DEBUG for your production build and DebugLog won't be called at all.
And don't forget to #import 'DebugLog.h'.
I'm trying to use a recent feature of the Scintilla component, which provides OSX-like text-highlighting effect (the yellow animated bouncing box), and I'm stuck with an error that pops up intermittently :
EXC_BAD_ACCESS
pointing to this particular line :
if (layerFindIndicator!=nil)
if ([layerFindIndicator animationForKey:#"animateFound"])
[layerFindIndicator removeAnimationForKey:#"animateFound"];
(the ifs are mine; just in case I caught the object layerFindIndicator being nil, or deallocated or whatever... Unfortunately, it doesn't help...)
layerFindIndicator is seemingly a subclass of CAGradientLayer. (You may see the full code for layerFindIndicator, here).
Since, I'm an absolute newbie to Quartz Core, could please give me any hint as to HOW this could be debugged?
Since, I'm an absolute newbie to Quartz Core, could please give me any hint as to HOW this could be debugged?
This doesn't have anything to do with QuartzCore specifically (at least, I hope not)—it's general this-object-has-been-killed-before-its-time-how-do-I-find-the-killer stuff.
In Xcode:
Edit your current scheme.
For the Profile action, set it to use the Debug build configuration.
Dismiss that and then hit the Profile command.
Xcode will build for that action and then launch Instruments.
Instruments will prompt you to choose a template; you want the Zombies template. Once you've chosen it, Instruments will create a trace document and run your application. Switch to your application (if it isn't already frontmost), then do whatever causes the crash.
If the crash really is a dead-object crash, Zombies will reveal it. You'll get a flag in Instruments's timeline saying something like “message sent to zombie object 0xd3c2b1a0”, and your program will probably exit shortly thereafter.
In that flag is a tiny little button that looks like this: ➲ except it'll be gray. Click on it.
That takes you to the history of that object (actually of that address, including any previous objects or other allocations that have started at that address). Show your Extended Detail Pane (the one that appears on the right showing a stack trace), then scroll down to the end and then move backward (upward) step by step through time, looking at releases and autoreleases, looking for the one that isn't balancing out the object's allocation or a retain.
The solution will probably involve one or more of:
Changing a property to be strong or weak rather than assign/unsafe_unretained
Adding a property where you previously did not strongly own an object
Rearchitecting some things, if it's not clear which of the above you need to do or if either one of them seems like a filthy hack
Switching to ARC to get weak properties and __weak instance variables (both of which get set to nil automatically when the referenced object dies) and to get local variables being implicitly initialized to nil
But it'll depend on what you find in Instruments. And, of course, there's the chance that your problem—the bad access—isn't a dead object at all and all of the above will not help you.
Try this:
if (layerFindIndicator!=nil){
if ([layerFindIndicator animationForKey:#"animateFound"]){
[layerFindIndicator removeAnimationForKey:#"animateFound"];
}
}
Also check to see if it is released else were.
EDIT:
Another thing I found was you didn't have an white space in the if. Your code should now look like this:
if (layerFindIndicator != nil){
if ([layerFindIndicator animationForKey:#"animateFound"]){
[layerFindIndicator removeAnimationForKey:#"animateFound"];
}
}
I am getting a crash in my app due to the following error:
-[NSCFString count]: unrecognized selector sent to instance 0x612b060
Can anybody tell me what does it mean and how can i find the line in my code with reference 0x612b060
You are calling count method on an object (probably a collection e.g array, dictionary, or set) which is released or has not been initialized yet.
You are sending message "count" on NSCFString, means, calling "count" method on NSString datatype.
To find the code, you can use Stack trace, but I am sure what you are doing is:
Assign NSString data on NSArray or (Array datatype) and trying to count.
Most likely this happens because you have a collection object (eg NSArray, NSDictionary) that you do not retain properly.
Try to use NSZombies to find the object that got released.
Right-Click on the executable in the Executables group in Xcode. Select Get Info
Select Arguments tab.
In Variables to be set in the environment create a variable called NSZombieEnabled and set its value to YES. Don't forget to activate it.
Turn on breakpoints and run your code.
the debugger will point you to the object that gets released to early.
After you've done debugging this problem you should deactivate NSZombies. NSZombies won't release any memory, it just marks the objects as released.
So you will end up in a memory warning sooner or later.
You can simply remove the checkmark in front of it to deactivate NSZombies.
Did you mean to call length on your string?
Maybe someone will need this:
When I had this kind of problem I used:
[ myarray retain];
after
myarray = [NSArray arrayWithObjects: ...];
and it worked. I think it was because my array destroying itself too early.
But I don' t know how I can now release this object?
Just [myarray autorelease]? Is there something opposite to retain ?
A practical example:
Sometimes, there is a practical difference which I don't understand clearly yet. valueForKey didn't work in SOGo-3.1.4's code trying to call an unavailable "method" ASProtocolVersion on the context object:
`EXCEPTION: <NSException: 0x55f43f93e4d0> NAME:NSInvalidArgumentException REASON:-[WOContext ASProtocolVersion]: unrecognized selector sent to instance
whereas objectForKey works (and is the usual way to query the context object elesewhere in the code).
See https://github.com/inverse-inc/sogo/pull/217/files