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.
Related
Recently I have been working on an old swift project built in back in 2015. Its really difficult to find which ViewController is executing currently because of the naming convention, usage of really massive storyboard(I feel terrified to even go to the main.storyboard) and various reason like usage of different language. Of course I can find it but it takes long. I was thinking if there is any way like when I run the project on a device and navigate to different page is there any way to see in the console which ViewController is executing ?
There is a quick way to find what view controller you are on when you are running your app.
1) Launch your app on the device or simulator.
2) Go into Xcode and tap this button:
3) This will open the Debug View Hierarchy. Click on the phone and you will see all the elements in the top bar. You can also see a hierarchy on the left-hand side. In here, you can click down and you will see the name of the view controller on screen.
Using the debugger after putting a breakpoint where you prefer you can write this and press return.
Swift 4.x
po UIApplication.shared.keyWindow?.rootViewController?.value(forKey: "_printHierarchy")
This method is a private API, thus you cannot use on production code, just use it in debug or from the debugger console.
I think it is better to see in debug area for your current viewcontroller named self, you get all information from there open the dropdown and and see you need to put break point in your viewController init method or where you want to debug, However you want to know programatically which is you current viewController you can get it by
appDelegate.window.currentViewController()
If you need which ViewController is Pushed or presented you can get from the above code but the case will be different if you are using the Slidemenu controller, I mean it is totally depends on how you have started navigation and which navigation controller is currently is use.
Can you briefly describe why you need current ViewController so i can help you further.
I have a view controller that keeps reloading over and over again. I would like to be able to see which methods are being called so that I can see the one that keeps firing the reload. I know I can see what was called if an error occurs and the app crashes. However, in this case there is no crash. Is there a way to monitor all of the methods being called throughout the app?
If you are new to XCode and Objective C and looking for something lightweight and you do not have a large code/ many methods, I would put:
NSLog(#"%s",__PRETTY_FUNCTION__);
in every method.
Use Instruments. Start your code in a profiling mode and select the CPU time instrument. As the app runs, Instruments will gather information about every call stack at regular intervals, which will allow you to see what calls what. (Use the "Invert Call Tree" option to see callers of a given function.)
I use this macro:
#define DEBUG 1
#if DEBUG
# define NLog(fmt, ...) printf("%s\n", [[NSString stringWithFormat:#"%s:%d %#", __PRETTY_FUNCTION__, __LINE__, [NSString stringWithFormat:fmt, ##__VA_ARGS__]] UTF8String])
#else
# define NLog(...)
#endif
Then I include my Macros.h in my Application_Prefix.pch file, so that it's available everywhere. Before I ship, I set DEBUG to 0 so that all NLogs disappear.
So now, instead of using NSLog, I use NLog. The output looks something like this:
-[ApplicationDelegate applicationDidBecomeActive:]:86 applicationDidBecomeActive called!
This solution was based on these earlier posts:
How to print out the method name and line number and conditionally disable NSLog?
Do I need to disable NSLog before release Application?
You can just place the NLog calls in several places, to see which functions are called right before your view controller reloads. If you need to know the exact function that triggered the reload, your best bet would be to place a breakpoint and examine the call stack, as others have mentioned.
I have an issue running an app on a simulator.
The problem:
EXC_BAD_ACCESS occurring at objc_msgSend in Thread 1.
Screenshot :
In my Application, I have multiple ViewController. when I click on back button of UINavigationBar then this type of issue is generated, I can't explain my problem because all the functionality works properly.
Example :-
1 - fitstVController (work properly)
=> it have UITableView, when I click on specific row then it will go on another UIViewController (SecoundViewController)
2 - SecoundViewController (work properly)
=> it have UITableView and UIActionSheet. when I select button of UiActionSheet then another UIViewController (ThirdViewController) is open
3 - ThirdViewController (work properly)
=> it have UITableView and multiple UIPickerView. But HERE IS PROBLEM THAT I CAN'T GO BACK AT PREVIOUS UIViewController (SecoundViewController).
=> when i do that then EXC_BAD_ACCESS (Code = 1, address = 0x30000008) issue generated.
In short, this type of problem occurs when you release the memory assigned to an object that has been already released. Most likely, this type of issue is generated when you go back to your previous UIViewController (or other cases).
And also, I suggest reading the following link for a more thorough explanation:
Hamster Emporium archive:So you crashed in objc_msgSend()
Setting an exception breakpoint means that Xcode will stop execution as soon as an exception is raised. It's not entirely foolproof, but this will usually result in the app breaking on the line of code that caused the problem.
That makes it a LOT easier to track down the source of the problem - although the stack trace is the definitive way of diagnosing issues, it's often far too detailed to be of much use (especially if like me you're not a compiler expert.)
To set this up, click on the Breakpoints symbol in the Navigator panel and click the + button at the bottom. Then select Add Exception Breakpoint, and Objective-C from the List of choices.
As #TimD has rightly pointed out, you can set an exception breakpoint and it will highlight the offending line of code (rather than trying to decipher the assembler or manually trying to identify where the problem is). And, as always, when diagnosing these sorts of memory issues, you should always enable zombies. Finally, especially important in non-ARC code, you should run your code through the static analyzer as many memory related problems can be identified there. You should always make sure you have zero warnings from the static analyzer as it invariably points out critical programming errors.
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 have an iphone app with a modal view. The app crashes when the modal view get dismissed.
As soon as the modal disappear at the bottom of the screen, and consequently the original view is shown behind, then the app crashes with no entry in console view.
I have tried to switch debugger on and I discovered that the app just run fine, with no crashes at all.
-First, I would like to know why such behaviour, shouldn't the debugger sit just on top without "disturbing" the app ?
-Second, without debugger, can you point out what should I look at to solve my problem ? Or if you encounter something similiar ? Please be as much specific you can, because I am not an expert in objective-c programming.
I don't know what details to give you, the app is a normal one with standard iphone component, but for start I can say the modal view (which is built with IB) is called inside a NavigationBar system.
thanks
When these types of things happen, it is almost always because of memory allocation issues. The first step I would take is to do a "Clean All" and a "Build and Analyze", and look at all the analysis warnings. Analyze is very good at finding basic "use before allocate", "use after deallocate", or "wrong number of retains/releases" types of problems.
The next step is to turn on "Zombie" detection mode, which looks for accesses on memory that has already been deleted (in other words, killed objects coming back from the dead.) To do this, get info on your executable, go to the Arguments tab, and add a "variable to be set in the environment" of "NSZombieEnabled" to value "YES". Then look in the console when you run to see if something looks off.
Finally, you might try creating a new configuration where you use all the release mode settings for optimization, but add debug symbols. Maybe that will shake up the allocation disbursement in memory enough to trigger the bug in debug mode.