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.
Related
I'm using xcuitest framework to automate mac application. I get system dialogs when the app is opened again after it crashes. I want to handle the dialog programmatically. But the dialog appears under the process `UserNotificationCenter' instead of the application under test. How can I handle the alert in such case?
You have two options:
Use InterruptionMonitor (documentation, use-case). This
approach is however kinda old and I found, that it does not work for
all dialogs and situations.
Create a method, which will wait for some regular app's button. If the app's button (or tab bar or other such XCUIElement) is visible and hittable after your app started, you can proceed with your test and if it's not, you can wait for the UserNotificationCenter dialog's button and identify&tap it by its string/position.
I'm using the second approach and its working much better, than the InterruptionMonitor. But it really depends on your app layout and use-case.
You should be able to revent it from appearing in the first place. Something like:
defaults write com.apple.CrashReporter DialogType none
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 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've build a simple app activating something in hardware, not important.
Now I just want the app to terminate completely if the user leaves the screen, switches apps, gets a call, press the home button, etc.
I'm all mixed up by all the application states, I couldn't find the right place to handle it.
I guess I need to listen to an "going to sleep" event and put a termination command (exit!)
or something like that.
This is easier than what one might think.
In your app's plist file define (check) the option "Application does not run in background" (UIApplicationExitsOnSuspend), and you are done.
Can any one guide me that how to use and identify the variables that are leaking the memory?
I took the snap as following, but yet no idea to understand it
Open the right utility area (click third button next to the status info in the top bar).
when you then klick on a leaked block (and on the arrow next to the address), you can see the code blocks responsible for the steps