I would really like to see every method, delegate, notification, etc. which is called / sent while I run my app in the iPhone Simulator. I thought the right place for this would be in the debugger, but I can't find the right setting.
My target is to see all that is happening in the background while I, for example, add a row to a UITableView or push the 'back'-button from my UINavigationController.
This would be a big help to figure out what delegate to use when something in the app is happening or when the user is pushing a button, changing a view, etc.
Is it possible to get this information?
You can log out everything that is happening when your application is running using DTrace, a framework that lets you probe the inner workings of anything running on a modern Mac. We don't yet have DTrace on iOS, but it will work while you're running within the Simulator.
I describe the fundamentals of DTrace in this article for MacResearch, then provide an example of a custom instrument you can build in Instruments using DTrace near the end of this article. That instrument logs out all methods called on all objects (even internal system ones) from the moment your application starts until it hits the end of -applicationDidFinishLaunching:.
To simplify this, you can simply create a custom instrument using the Instrument | Build New Instrument menu item in instruments. Set up one of the probe descriptors to look like the following:
only ignore the isInApplicationStart and timestamp logging options. A simple probe responding to any Objective-C method in any class will log all of those messages to the Instruments console, which sounds like what you want for your debugging.
Assuming you're sure you want absolutely everything...
Breakpoint objc_msgSend and objc_msgSend_stret. Almost all method calls use those two functions (mumble mumble IMP-cacheing).
Okay, now your app drops into the debugger all the time. So click the auto-continue box.
But now you don't see very much happening, so edit the breakpoints and add the command "bt" to get a backtrace.
Drown in debug spam.
This won't catch other C functions, of course.
If you just want to catch notifications, you can do something like this (much less spammy):
+(void)load
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(handleEveryNotification:) name:nil object:nil];
}
+(void)handleEveryNotification:(NSNotification*)notification
{
CFShow(notification);
}
Of course, notifications are done with normal method calls, so the first method will also show them (albeit in a big pile of spam).
Delegates are not called or sent; they are just normal Obj-C method calls (strictly "message-sends", but that doesn't have the same ring to it).
If you put a breakpoint into your app, you can watch the call stack change while you step through the code. That's probably as close as you're going to come to what you have in mind.
Related
I am building a word game and I want to hide the board when application is suspended?
the code looks fine however it givs a strange behaviour!!,
when I suspend the app nothing will happen but when i resume the application then the board will hide!!
local onSystem = function( event )
if event.type == "applicationSuspend" then
print("suspend")
board_group.alpha = 0
end
end
Runtime:addEventListener( "system", onSystem )
Note: you might wonder how do I know how the application looks when suspended?
the answer is: by pressing the home button twice.
example
SpellTower in normal state
https://dzwonsemrish7.cloudfront.net/items/430k0c0b0y0b413d0b42/Image%202012.11.12%208:08:24%20AM.png?v=4822f549
SpellTower after pressing the home button twice
https://dzwonsemrish7.cloudfront.net/items/280a1y0r2U3W321y1B2z/Image%202012.11.12%208:08:31%20AM.png?v=09c37567
you can see how they are hiding the letters, this is exactly what I want to do for my game, the only difference is i am using Corona SDK
When you do board_group.alpha = 0 you only has set a variable, the result will only take effect after a screen update.
But since the application is suspended... it won't update! So, changing any graphics on applicationSuspend don't work.
I believe the reason is because the application is not considered as suspended. In normal objective c programming it means that applicationWillResignActive is called when the user double clicks on the home button. So what you want to do is to add that code for this part.
Here is a flow of events:
http://www.cocoanetics.com/2010/07/understanding-ios-4-backgrounding-and-delegate-messaging/
Corona seems to have these events:
"applicationStart" occurs when the application is launched and all code
in main.lua is executed.
"applicationExit" occurs when the user quits the application.
"applicationSuspend" occurs when the device needs to suspend the application such as during a phone call or if the phone goes to sleep
from inactivity. In the simulator, this corresponds to the simulator
running in the background. During suspension, no events (not even
enterFrame events) are sent to the application while suspended, so if
you have code that depends on time, you should account for the time
lost to an application being suspended.
"applicationResume" occurs when the application resumes after a suspend. On the phone, this occurs if the application was suspended
because of a phone call. On the simulator, this occurs when the simulator was in the background and now is the foreground application.
So my guess is that you have to implement it outside of the corona API.
According to the corona documents you can implement them in the delegate:
You can intercept UIApplicationDelegate events via your implementation
of the CoronaDelegate protocol.
This protocol conforms to the UIApplicationDelegate protocol. Corona's
internal delegate will call your protocol's method if it is
implemented.
Please keep in mind the following:
Methods that Apple has deprecated will be ignored.
In most cases, your class' version will be invoked after Corona's corresponding version of the UIApplicationDelegate method. There is one situation in which your version will be called before.
In situations where the app is about to suspend or go to the background, your method will be called before Corona's version, e.g.
applicationWillResignActive: and applicationDidEnterBackground:.
http://docs.coronalabs.com/native/enterprise/ios/CoronaDelegate.html
But this is just a guess. Hope it helps!
Edit:
I was thinking, something really simple you could do is catch it outside and present a "pause" screen, then just hide it when the application enters foreground.
So if you can't do that (for now), one other option is to save application state when the application is about to terminate, and then set UIApplicationExitsOnSuspend = true in your plist file. This will cause the application to exit instead of suspending, which will avoid any screenshots, effectively "hiding" the board, etc. The downfall is, the app will have to read the session state when it launches again... this is only useful if your application can be designed to actually exit without losing your state, and is quite honestly, a little extreme. That said, it may be the only way to effectively do what you're trying to do.
Other ideas would be to see if you can add a large black layer to the screen, even though the application is suspending; perhaps this will somehow trigger an internal screen update by natively setting setNeedsDisplay. Also, instead of modifying the alpha, you might consider temporarily removing all of your layers and see if that has a similar effect.
In application that I work on it, I need to close it from code. I'm using exit(0) for that.
Yes, I know that i shouldn't close application from code
When I close application in this way, and run it again, there is some strange behaviur - application doesn't start nor from splash screen, like new instance of app, neither from last view, like application turning back from background.
Instead, for a second some random, non-interactive view of my app is appearing, and after this splash screen start to run.
I'm confused because I cannot find source, and how to fix this ugly bug. Can you help me?
This is exactly the problem with exit(0). You get weird multitasking behaviour and all sorts of other problems.
You simply can't terminate your application in code. You should explain to us why you think you need to quit programmatically so we can help you find an alternative solution.
From Technical Q&A QA1561
There is no API provided for gracefully terminating an iOS application.
Do not call the exit function. Applications calling exit will appear
to the user to have crashed, rather than performing a graceful
termination and animating back to the Home screen.
Additionally, data may not be saved, because
-applicationWillTerminate: and similar UIApplicationDelegate methods will not be invoked
if you call exit. If during development or testing
it is necessary to terminate your application, the abort function, or
assert macro is recommended.
Instead of
exit(0)
try this:
[[UIApplication sharedApplication] performSelector:#selector(terminateWithSuccess)];
I have an app where I have 5 sets of animations that I'm storing in an array. The animations get picked to play randomly after a button touch. This is all working perfectly, however I noticed a bug when I quit the app and reopen immediately, I'll see my main view, then it'll jump to my second view that has the animation in it. (This shouldn't happen since you have to tap the main view in order for it to modally swap in the second view. If I interact with it everything works for a few seconds, then it closes with no crash log.
I finally realized that some of the objects must not be getting released fast enough, since if I close the app and wait three seconds, then reopen, everything executes fine.
I didn't want to put down code to show as this is more of a brainstorming question. I'd love any insight that could point me the right way. I changed a lot of my code to get rid of convenience methods and have all my variables defined and then released in my dealloc.
Is there a way to truly tell the app to kill everything on quit? It's not set to run in the background so this is a bit odd. Thanks for your help I'm still new to this and learning!
Alright, after working on this all weekend and doing more research comparing a barebones version of my app to my prerelease version, I traced memory leaks to the Flurry Analytics api that I am using. Apparently I was suffering from the same issue as the post here: App hangs on restart with latest Flurry SDK and ios4 . I resolved this by setting these optional methods to false, since they take extra time to send data after the app terminates, and depending on the connection it takes a few seconds.
FlurryAnalytics.h
/*
optional session settings that can be changed after start session
*/
+ (void)setSessionReportsOnCloseEnabled:(BOOL)sendSessionReportsOnClose; // default is YES
+ (void)setSessionReportsOnPauseEnabled:(BOOL)setSessionReportsOnPauseEnabled; // default is YES
Hope this helps anyone else who experienced something similar to me!
All apps can enter the background by default. Normally they do not do anything there, but they stay there in a frozen state and when you open them again, your program does not restart, it just picks up where it left off.
Anything that's set as an animation delegate might not get released, since it's retained for that purpose until the animation completes.
You can add an applicationDidEnterBackground: method to your app delegate to get informed when your app is going into the background, but exactly what you need to do depends on the design of your app. You can also add applicationWillEnterForeground: to do anything you need to do differently when restarting, as opposed to newly starting.
You might be able to force your animations to complete by starting a new animation with duration 0.0 (or very short if for some reason you can't do that).
If this happens only if your app goes to bkgnd and comes back AND you don't mind if the app restarts everytime it comes back then just put UIApplicationExitsOnSuspend in your app's plist. In all my cases where these and other bad things happen with apps going to and returning from bkgnd this helped.
While you might still see the app on the buttom when double tapping it is really stopped and will restart. Apps that show on the buttom do not always have to run or be stored in the bkgnd I learned.
ps. don't forget to set the value of UIApplicationExitsOnSuspend to YES
Can I "profile" for memory leaks using a Test Case? (i.e. focused run on a defined area of code) I tried changing my profile for my iPhone app to Unit Tests and then noted the "profile" option disappeared.
My goal (requirement) I guess is to be able to isolate a specific method, and then run the Instruments memory leak profiling across this specific method and observe results.
The easiest way to accomplish this is to launch your application in Instrument, wait a little and tap a button that will run the specific method you're looking for.
You can then select the timespan where the method ran by dragging the time bar with the option key.
You can also set a breakpoint in your tests, use Instruments to attach to the process, and then resume. Don't forget to hit Record like I did :)
I am trying to access the UITextView delegates and have a problem
I have a UIViewController with the UITextViewDelegate protocol and a Nib containing the textView.
If I set the delegate inside viewDidLoad like "textView.delegate = self" and I touch the textView, the app crashes without logging errors.
If I start editing the textView with code like "[textView becomeFirstResponder]" all delegates get called.
When I set the delegate in the Nib creating a connection between the textView and the File's owner and deleting "textView.delegate = self" also no delegates get called.
What am I doing wrong here?
Regards,
Elias
It's not easy to help you without more description, posted code or a xib file.
You say application crashes without any logging errors - well, do you mean that there's no output in console's window ? That is normal, for an app that has crashed.
Anyway, you should be able to get the stack-trace to figure out where approximately the application has crashed. Open the debugger (⇧⌘Y), and see the position. That should give you an idea of what went wrong.
Here you can see an example of such debugger session (after EXC_BAD_CRASH):
First two lines doesn't give us much information, but later on we can see that application has crashed while loading user interface from a NIB file. Well, usually the only code that executes during such load are awakeFromNib methods - it's up to you to find a problem along those lines.
Often top of code's execution doesn't make any sense - for example you might see your ViewController method somewhere, but the top few function calls (those where the code crashed) are located in methods/classes which you never call in your code. In most cases that is a sign of wrong memory de-/allocation. What might happened is that you forgot to retain some of your objects, it has already been released, but you are still keeping reference (a pointer) to its memory. Because that memory has been in fact freed, another object took its place later on, usually some Apple's internal object you've never heard about. Later on your code tries to message your poor object but it sends a message to something completely different. BUMMER! That's how you get those crashes and strange stack traces.
To fix the kind of problem I've just described you can use Instruments and its Zombies instrument. Unfortunately you can't start Zombies from within Xcode, you need to start Instruments standalone, then choose the Zombies under iPhone Simulator/Memory, then Choose Target from the toolbar, you should see your application in there, or be able to navigate to it on filesystem.
What Zombies instrument does is that it never really frees memory after objects are deallocated. Instead, it will mutate those objects into NSZombie class. That class intercepts all calls to itself, and informs you when some code is trying to send a message to it.
This is how such Instruments session looks like (this is the same crash as seen in debugger above):
In the table you can see that we're trying to message UIScrollView that has already been deallocated. You can as well see the whole history of retain/release calls to this particular object. That way you can find a missing retain or wrong release/autorelease.
Remember - Zombies Instruments can only be used with Simulator, because there's not enough memory on the real device to keep all those memory blocks.
Hopefully I could help you with further analysis of your problem.