I have created two ios app A & B. I made custom URL for app A and tried to opened it through app B. But the app A crashes when it opened. I want to debug it. How will I do that?
I presume that you know how to debug (if not, that's a different question), and that your problem is how to set a breakpoint when the application is launched from a URL rather than by yourself directly.
What you need to do is to setup breakpoints normally anywhere you need them - e.g. in applicationDidFinishLaunching Then
Click on your application name 'A' in the bar and then Edit Scheme.
Under Info, select "Wait for executable to be launched"
Run app 'A' from Xcode. It will not actually run, but prepare to debug it when it is run.
Now run app 'B' and launch app 'A' from it.
Click on the break point navigator in the xcode
Press the plus icon at the bottom left of the window and add an Exception Break point.
It will give you enough information when the app crashes and you will be able to back track and find the cause
It is hard to paste all the code because I do not exactly know what is happening. My app is using a Tab Navigator as it's main navigation, and it works perfectly fine when I run it normally.
HOWEVER,
Whenever I forcefully quit it using the Android left button, it stops working when I reopen it.
Once it is re-open, I am able to swipe through all my tabs but each screen is FROZEN. I cannot click anything and the Tab Navigator does not update (it shows the initialRoute still selected).
I am very confused on what is causing the problem, my initial guess would be something to do with listeners but I really don't know which part of my app causes this. I have added the Firebase tag for this reason. I would like to try turning off all my listeners if the app is force closed, but I don't know if this is possible.
Other details:
I mostly use 'on' listeners.
Thanks.
I am working on a keyboard app and I come from a PHP background. I was asked to see if I can get long presses working on the keyboard (when you hold down on A for instance, all the accents should show).
I have tried a few things and now when you press on A, it acts like something is firing off, but fails, and the keyboard switches to the default emoji board instead.
The debug window in Xcode is blank. There doesn't seem to be an active console log like you would use with JavaScript, so I am completely stumped on how I can figure out what's happening. If I could see that it's failing on a certain function, then I would be able to know where to start fixing problems.
Also, I tried using breakpoints but they never were hit.
For some reason, Xcode is not displaying the line number of the exception, or even the crash itself in the Debugger Output. I have no breakpoints set and it's being built for Debug. The debugger is set to LLDB. I'm not sure how this became onset, but it's badly affecting my workflow now.
This isn't how it was before (would display main.m), but I have no idea how it happened.
Turn off your breakpoints. Up in the top bar, unselect the button labeled Breakpoints.
You likely accidentally clicked on a line and enabled a breakpoint. Additionally, you can click on the button that looks like a play button with a line preceding it to continue the program execution. It is located on the bar above your console output.
This is more of a general annoyance. Every time after stopping the simulator, Xcode jumps to main.m for some reason. On the left nav, it jumps to the Debug Navigator.
Is there a way to fix this?
It's annoying because I might be testing a certain line of code, and now each time, I need to make a couple of clicks just to go back to that code.
This problem is not new, seems to get worse though. At the time of writing this, I was on the GM seed, but this problem persists in XCode 4.2 final. This was not a problem in previous versions of XCode.
When we start debug from xcode, the debugger sets itself up to monitor signals from OS. When we press stop button in XCode (or hit cmd + R - which first stops existing instance running and then try to start new one, somewhat equalant to we press manually stop first and then run) SIGKILL is sent to the debugger.
Whenever the cause of interruption is from outside the app (in other words all cases where SIGKILL is sent, like stop button press) , debugger jumps to main, since main is the root of the app and the place where your app meets the OS. Debugger has no way to identify why this SIGKILL is issued (pressing stop button in xcode/ press cmd + R/ delete app from multitasking bar etc), but it treats SIGKILL as outside interrupt, and nothing related with your code. So it jumps to main.
If the cause of interruption is from inside the app (like app crash/SIGABRT) debugger handles it and jumps to the place of crash, which we normally see.
I do not consider this as an xcode bug, rather a normal way of handling SIGKILL. But if you want to stay at your code and do not want to jump to main you can do two things
You can do as Gabe suggested. As BBonified said, it is like a band-aide,
but I think it should work (personally I never tried that)
Report a bug/request for a feature here. Let me tell you you
are not the first one to do so. Already a bug has been reported. See
this and this. But I don't have much hope of a positive action from Apple
And I agree with you, it is sometimes annoying. Especially if you have experienced differently in previous XCode versions. But we can only take what they give here.
I guess it's fair to call it a bug, Xcode 3 specifically suppressed this useless artefact.
I've had success (four times and counting) with this one-liner in ~/.gdbinit:
handle SIGKILL nostop noprint nopass
Taken from this gdb manual:
http://www.delorie.com/gnu/docs/gdb/gdb_39.html
Not sure if it applies to lldb as well.
I tried what David suggested but that didn't work for me, so I tried something similar:
Open Preferences, select Behaviors tab.
Select "Run exits unexpectedly" from left column.
Select "Show debugger with current views".
I'm using Xcode version 4.2 build 4D199.
EDIT: That worked for about 15 minutes. Then it reverted to bringing up main.m in the editor again.
I had the same problem and it WAS really annoying, especially when you were in the middle of debugging, stopping/launching the app several times in a row after small modifications.
Everything is solvable through settings in Xcode user preferences:
Just go to "run completes"
There find the "Show" line and click the checkbox
On the same line modify target to go to "Current" in the dropdown menu.
There you go. Xcode will not move your editing view from now on. Enjoy.
PS: Xcode version 4.2 Build 4C199
Go to Preferences -> Behaviors. Choose "Run Completes" in the left hand side. Check the box next to "Show Tab" and enter a tab name. I use "Edit". This way whenever you stop, you will always be back at a tab called Edit.
None of the other solutions listed were suitable for me, so I made a macro (using an external hotkey utility).
(wait 0.1 second after each step)
command-period
command-1
down arrow
up arrow
command-j
enter
Use this key instead of the normal stop, and you end up with your cursor positioned where you left it. Very nice.
Xcode -> Preferences
Under Behaviors
Click on Run Starts
Checkbox for [Show] debugger with [Current Views]
...worked for me.
None of the preference adjustments seem to work for me.
I have been able to track the offending sequence of events. The SIGKILL error message will occur when you run your app and use multiple threads. For instance, when using UIWebView in my app it will abort to main.m. I verified that when UIWebView is not called, XCode can be stopped without the SIGKILL error message returning the user to main.m
It looks like there are at least two threads that get started when initializing a UIWebView.
However, any threads created by you during the running of your app will cause the SIGKILL to improperly notify XCODE to return to the main.
You can see this in the GDB that there is a switch just before SIGKILL:
[Switching to process 24957 thread 0x2103]
[Switching to process 24957 thread 0x7403]
[Switching to process 24957 thread 0x207]
Program ended with exit code: 0
It is definitely still a bug with XCODE that will hopefully be fixed.
For now, if you avoid executing code that launches a separate thread, it will not change the view back to main.m For code that does launch additional threads, I would recommend quitting the simulator to return to edit mode in XCODE.
None of these solutions worked for me and I find the behavior too intrusive to put up with.
I get round it by using the 'Assistant Editor' instead of the editor as my main editing window. You access the Assistant Editor using the tiny little bow tie button at the top right of the single window.
You can set then it to 'Manual'. Click on the button that is the far left crumb of the breadcrumb trail at the top of the Assistant Editor frame and select Manual from the pop-up menu that appears. The Manual setting allows you to select the file you're editing by clicking on the second to last crumb of the breadcrumb trail and selecting the file from the pop-up that appears.
I then just minimize the size of the main editor - or use it as a secondary editing window, useful given that you can't split the editors into multiple frames any more. Far from ideal - but that's XCode 4 for you.
This might not be much. I was able to avoid this problem 99% of the time by waiting for 2 seconds or so after stopping the app, before relaunching it.
UPDATE: After upgrading to the latest Xcode, I am prompted to use LLDB instead of GDB. The problem seems to be gone now.
I was trying to find the offending line when my code was breaking, so what I did was:
Go to where you define your breakpoints (breakpoint navigator, according to the documentation)
Click in the "+" sign in the left bottom corner of the navigation area
Click on Add Exception breakpoint
You click Done
Run your app
Xcode shows you the offending line.