Where XCode generate error for application crash ?
I'm crazyng ! My application when open second file xib with webview then it crash. But I don't know why ? how can i Know where is error ?
You need to learn how to use the debugger in Xcode.
Run your app under the debugger then instead if simply getting a stack trace Xcode will stop at the line the fault occurs and show you your code and variables. You can then examine the contents of your variables, the call tree, etc. and hunt down the problem.
Once you know the general area of the problem you can place breakpoints to pause your application before the problem occurs and check whether your variables have the values expected etc. Then you can run till the next breakpoint, or step through your code a line at a time.
You can add code, such as NSAssert's and NSLog's to your app to check progress and display information without stopping the run, etc.
It's a process, and some problems will be harder to track down, but you'll get quicker at it with practice.
The Xcode documentation will tell you all about the debugger.
HTH
Related
It's been bothering me since Xcode 6, that whenever I set 'All Exceptions' without any other breakpoints, Xcode would stop at start when I init a UILabel view wrapper in RootVC.
If I try to remove the causing line, another "random" line would trigger it again. Thoughts on what caused the exception?
This breakpoint comes from an exception that was thrown by TFileDescriptorContext. All Exceptions halts also on C++ exceptions.
It gives you a good indication where the problem comes from. Take a look if all fonts that are listed in Info.plist are part of your application bundle.
"Normally" you are not interested in C++ exceptions when you are in Objective-C, so feel free to ignore them.
Edit: This problem has been discussed several times here on SO. Updating when I can find the posts again which might give you even a deeper insight.
Long story short, I am debugging a big application which I didn't write. It is throwing an error when it runs on the server on which it is supposed to be run, so I am testing on my own machine with the debugger attached to see what happens.
It has thousands of lines of code, and has been running for a couple of hours now. I want to know which line of code is currently executing, so I can get a rough idea of how long is left, but I don't want to Break All as the code is...rickety.
Short of firing watchpoints all over the place in a spray and pray fashion, is there a non-invasive way to see which line of code is executing right now?
Thanks
Process Explorer can show the currently executing line and call stack in the process.
Right-click a process, click Properties, and then click the Threads tab.
I'm currently (trying) to develop an app with Worklight Studio 5.0.6 and Dojo (Mobile) 1.8.3. I have a really hard time to to find a proper method for debugging. After waiting 5-10 minutes for the build an deploy-process on the server, an error usually looks like this in the Chrome debugger:
How am I supposed to track down this error in MY source? The whole stack trace consists entirely of Dojo code which generates an absolutely useless error message after 20 abstraction layers.
Seriously, how do you guys handle this in real life? What methods do you use for debugging Dojo-driven apps in the browser?
spyro
For dojo.parse errors, I find it useful to pause the Chrome debugger on all exceptions (the purple icon on your screenshot, should be blue). You usally get more details about the cause of the error, the name of the DOM node being parsed, etc. in the first exception being raised.
Rémi.
Debugging dojo based application should be the same as debugging any javascript application.
Usually I will follow these steps:
add console.log() somewhere in code: this is fast and most of time this is enough.
set breakpoint in debugger: if step 1 is not enough, you can base on error information to set breakpoint before error line, then step in or step out.
comment out recently changes: for some error which is hard to find the error line, for example, parse error in your case, the good way is comment out your recently changes one by one till back to your last working version. Or, return to your last working version, then add code back one by one.
Create a simple application to reproduce the error : if your application is very complicate and it is hard for you to follow above methods, you can try to create a new application which mimics your current application but with simple logics and try to reproduce the error.
Based on experience : Some errors, for example, extra ',' in the end of array which works at chrome and firefox, will report a nonsense error information at IE. Debug these kinds of errors is very difficult, you can base on your experience or do a google search.
Did you provide isDebug: true in your dojoConfig? Also, try to see if the same occurs in other browsers.
Update: I recently discovered that there are issues with Google Chrome and Dojo debugging and I think it has to do with the asynchronous loading of files. As you can see in the provided screenshot of #spyro, the ReferenceError object is blank (which you can notice because of the empty brackets {}). If you want to solve that, reopen the console of Google Chrome, (for example by tapping F12 twice). After reopening the ReferenceError should not be empty anymore and now you can expand that object by using the arrow next to it and get a more detailed message about what failed.
Usually what I do in situations like that is to place a breakpoint inside the error callback (line 3398 in your case) and then look into the error variable ("e").
I am not sure how familiar you are with the Web Inspector, but once you hit the breakpoint open the Web Inspector 'console' and check for the error properties "e.message" and "e.stack" (just type in "e.message " in the console).
Also, during development it is better to avoid Dojo optimization / minification, which greatly improve your debug-ability.
Bottom line is to try to place the breakpoint before the error is thrown.
Here's my situation. I have an app installed on my system. It's running. I also have the source for this app and I've built it in XCode and had it generate dSYM files. I attached to the process in XCode. I've been trying to set breakpoints of the form "-[ClassName methodName]" (without the quotes) however none of my breakpoints are getting hit. Do I have to somehow point XCode to my symbol file or something?
I have never debugged using that method, but there is a much easier way. You can simply click on the line number of a code-bearing line and a blue arrow (a breakpoint) will appear there. When the application reaches one of these lines with a breakpoint, execution will pause an allow you to step through the code one line at a time.
The only error I ever get is SIGABRT in main. This is getting incredibly frustrating as I have to guess what line caused the error and why.
This is a far cry from visual studio's informative error messages. It's basically like sending off an entire novel to an editor and the only notes you get back are: "There is a problem somewhere in your book. There may be many or just one and they are either gramatical or to do with spelling."
I just don't know how anyone can work like this. What am I doing wrong? Surely I'm missing something essential.
Write some NSLog() into your code and you'll see it in the console. It's a great help to narrow down a crash.
if you have encountered memory problems (aka – your app crashes for no apparent reason because you attempted to use an object that you deallocated to soon) setting NSZombieEnabled = YES can help you diagnose the problem.
Normally, when your app crashes in this way and you look at the log it tells you nothing (thanks Apple!). However, if you select your executable (under Executables in Xcode), hit the info button (round blue thing at the top), select arguments and put this in the bottom screen NSZombieEnabled = YES the log will give you more information.
Now, if your app crashes the log will have an indication of the object you attempted to access that has already been deallocated. Not forget to turn it off before you deploy it – you don’t want a bunch of nszombies running around your clients phones…
http://howtomakeiphoneapps.com/nszombie-and-xcode-oh-my/27/