My app always stop running on this line, even there is no breakpoint and stopping on breakpoint is disabled.
When I click continue it's stop again on the same place to infinite. Basically I'm not able to debug this app anyhow, it started when I've added this func in class.
Any ideas?
before assign value to MCCVsISDCode kindly init it first.
This is not a user-created breakpoint, but Xcode's way of handling null-referenced crashes. In your case, force-unwrapped value of MCCVsISDCode returns nil.
Related
I made my project in storyboard in, due to issue with the custom UITableViewCell I have made a new project, copied all of the data to my new classes and copied my buttons, images etc from the storyboard views to new project's nib/xib files.
Now When I click on any button my app crashes without any error and it opens delegate file and highlights this line of code
return UIApplicationMain(argc, argv, nil, NSStringFromClass([ThisOrThatAppDelegate class]));
I have already made connections for the required actions from IB to controller. Also I have tried Command+Shift+K for clean code. But the problem is still there.
You have to find out first what the problem is:
use the Debug build config and are using lldb or gdb
make sure you have a breakpoint on all exceptions
make sure you have the "Breakpoints" button top left enabled.
run the app
You should break into the debugger. You need to get to a point where the debugger catches the exception.
Then edit your question and tell us what exception you get. I'm going to guess you'll be getting a objc_msgSend() error, which means that some object is trying to message a non-existent or dealloced object. If that turns out to be true, then you can enable "Zombies" (which lets all objects stay around) and see if one of those gets messaged.
If nothing seems to help, then what you need to do is start adding NSLog messages to track your app as it comes up (or use breakpoints, your choice). This takes a long time so you might work backwards - see if your appDelegate application:didFinishLaunchingWithOptions: gets called, and also if you get to the end of it.
Unforunately this type of problem can be take a lot of time to track down. Some object has probably queued a message up for another object on the main queue, so when you get the crash you don't get to see who did what when.
Also, with objc_msgSend problems, when the debugger stops you cannot easily see what object was messaged - but if you turn off the debugger and let the app actually crash, you can find the crash report in the Console app and get more info from that.
I am working on a large (>30k lines) event-driven app. I have a sequence of inputs that produces a bug. What I want to do is to break as soon as the final input enters my code.
Is there a general way to do that?
I understand that for any specific sequence of inputs, I can find out where that last input is going to enter my code, then set a breakpoint there. What I would like to do is take out the step of "find out where that last input enters my code." In other words, I am running the app in the simulator, and I want to set a flag somewhere that says "break the next time you are going to enter non-system Objective C code." Then I send the event that causes the problem.
I understand what you are asking, but have you tried using an Exception Breakpoint? This will basically act like an auto-inserted breakpoint on the piece of code that throws the exception. If that doesn't work for you, try a symbolic breakpoint
If you want to intercept UI events, you can try subclassing UIWindow and overriding its sendEvent: method, then setting this class as the class of the UIWindow object in your main XIB file. sendEvent: will be called each time the user generates a touch event. Unfortunately, at this point you cannot yet know which UI object will finally consume the event (read: which event handler code will be ultimately called) since that depends on the actual state of the responder chain. But anyway, you can use this method to inject events into the system.
My app crashes, but generates no exception in the console and no crash log on the device. No memory warnings are received. Is there any way I can narrow down the cause without having to comment out code?
Stepping through the code should help you nail down where the app is crashing, this will stop the program execution before it hits any "bad" code (providing you put the breakpoint - where the code will stop in the right place). You can add a break point by clicking on the appropriate line number to the left of the code editing pane and can access the break points organiser through the View->Navigators->Show Breakpoint Navigators menu.
You may have some inkling of the method or class that's currently being executed in which case you should put a break point on the first line of that method, if the class is a UIViewController then putting the break point on the first line of it's -(void)viewDidLoad method may help. You could, at a push, put your breakpoint on the first line of -(void)applicationDidFinishLaunching in the application delegate. However this will require a lot of stepping into instructions rather than just stepping over instructions.
https://developer.apple.com/library/mac/#documentation/ToolsLanguages/Conceptual/Xcode4UserGuide/Debugging/Debugging.html
Apple also suggest turning on the static analyser and then inferring problems in your code from it's output.
The reason for the crash was that I was logging a really large array with NSLog - did not know that could crash an app!
I have done some changes to my project and now I am getting above message when running the app and don't how how to debug it.
I have read here that I have to put a break point in -[NSCFDictionary setObject:forKey:] and set a condition as well.
But, how do I set the condition they mentioned? (Stop only when value is nil) I am on Xcode4 and only get this window when trying to set a breakpoint.
Currently it stops at every -[NSCFDictionary setObject:forKey:] which is not very helpful since it will stop even in correct calls and Apple's internal calls as well (too many!)
Remove that breakpoint and add an Exception breakpoint. This will stop on any exception (like attempting to insert nil into a dictionary). It's good practice to leave this breakpoint on for all debugging sessions, that way even intermittent exceptions (those hard-to-find problems) will be caught in the debugger the moment they happen.
To add an Exception breakpoint, click the Add (+) button at the bottom of the breakpoints list and click Add Exception Breakpoint. Leave it configured as-is.
if you have reduced it to a call site, you can simply write:
assert(object);
[dictionary setObject:object forKey:key];
I am loading the custom cell on tableView and i return 50 rows in the tableView.
number of some rows are display in the tableview but when scroll the tableview my customcell is not display and I have the error
"EXC_BAD_ACCESS"
and also display following message on the console
"void SendDelegateMessage(NSInvocation*): delegate (webViewDidLayout:) failed to return after waiting 10 seconds. main run loop mode: UITrackingRunLoopMode"
I think you get this error due to your method of making custom cells. When you made the class file for the custom cell in the .m file you released the IBOutlets. Try removing that portion from your code than try.
I had the same problem in an app, and I solved that problem this way. Maybe this solution will work for you too.
The best way to detect zombies is:
in the Groups and Files section,
expand the Executables section
and right click on your app name and
choose Get Info
select the Arguments tab on the top and then add a new entry in the Variables to be set in the environment section. Name the new variable to NSZombieEnabled and set its value to YES.
After this you will have information in console on which released objects you make calls.
This typically means that you have asked the program to look at a memory area that you don't have access to, which usually means you have run off the end of an array, or something.
If you are running in debug mode, the stack trace will probably give you more clues. Open up the debug console.
You should also use NSZombieEnabled, it usually helps. It shows you which deallocated object was accessed. Be sure to disable it after you use it because using this, no memory is ever released.