iOS 8 Debugging Case Study

http://www.objc.io/issue-19/debugging-case-study.html

by hoggle • 12 years ago

79 25 12 years ago

jparishy2• 12 years ago

This is a really great read, especially for new iOS developers who haven't picked up a ton of debugging tricks from experience alone.

In particular the section "Calling Conventions 101" contains a lot of very useful information that isn't documented very well in any of the iOS resources provided by Apple (AFAIK). Commit it all to memory, you'll be glad you did :)

micampe• 12 years ago

The calling conventions are described here https://developer.apple.com/library/ios/technotes/tn2239/ with links to more in depth descriptions and other useful informations.

This article has some more good tips on extracting information from those registers. http://www.sealiesoftware.com/blog/archive/2008/09/22/objc_e...

mikeash3• 12 years ago

Apple uses the standard calling conventions for the CPU architectures they use, so there's no real need nor expectation for Apple to document those aspects beyond saying "we use the standard conventions," which they do say if you go digging. In some instances they also replicate the documentation for the conventions.

jparishy2• 12 years ago

Well, for new developers they might not put together "we use this calling convention" with "and that means you can find things like self, _cmd, or the exception that was thrown in these registers ... which can ease debugging your app". That's useful information I wish they'd put up in their docs, is all.

stephencanon• 12 years ago

It's not obvious that you can meaningfully talk about to "the standard conventions" on i386, x86_64, or armv7, as there are at least two widely-used conventions for each. arm64 comes the closest to having a single "standard", but Apple uses a (documented) tweaked version.

davidbanham• 12 years ago

Does anyone else feel like maybe the entire iOS development experience is batshit insane?

tl• 12 years ago

I wouldn't say the entire experience is insane, but a lot of things feel unnecessarily difficult (hello crash symbolication, auto-layout debugging, etc...) compared to their web development counterparts.

On the other hand, you do get greater performance and stability (but not perfect stability, after all it wouldn't be an iOS release if Apple didn't break something and completely ignore radars).

coldcode• 12 years ago

Not really, I work on iOS code much more complex and rarely have to stoop to so many tricks. Due to having to support iOS 6 I still have to use XCode 5 so some of this isn't even available to me. After a while you figure out the problems just from the symptoms. My current project was written by Elbonians who were paid a pittance so there is lots of fun debugging.

That said figuring out bugs in iOS is a major league PITA. I have one now in NSURLSession which is batshit insane.

mikeash3• 12 years ago

There's a lot of extremely frustrating and stupid aspects to it... but none of those are in any way related to anything discussed in the article, so I find your comment a bit odd. What makes iOS development so frustrating to me is the constant struggle with code signing, device provisioning, Xcode crashes, random failures to install or run programs, and all the craziness around App Store review.

faizmokhtar• 12 years ago

I agree. I just started to learn iOS development at my current job (around 4 months), and configuring with code signing & XCode configuration is a pain in the ass.

alayne• 12 years ago

Not compared to my experience with other mobile platforms.

mogui• 12 years ago

have you ever developed something on Android? Oh man, that is insane!

Sephiroth87• 12 years ago

Debugging is insane?

archagon2• 12 years ago

No. I have never had to use the assembly/decompiling tips described in this article, and 99.9% of programmers will never have to do it, either.

Even with a problem like this, you can fix it or get around it with a bit of trial and error. As with any other black box technology.

(Still useful to know, though.)

serve_yay• 12 years ago

Seems so, but then I am a JS developer, and you know what they say about glass houses. And really, everything we do is completely nuts if you think about it.

coldtea• 12 years ago

No, sounds fairly typical native development experience, if not one of the best ones.

Plus the term "batshit insane" has been overused. What you'd use to call some really bizarro thing when you do see one?

zackmorris• 12 years ago

Yes. It all begins with having to provision your own device, and slowly slides into "people are strange when you're a stranger" territory from there on. The worst part is pointing out each individual folly, only to have it met with skepticism, criticism and fanaticism by Apple fanbois. Luckily Stack Overflow has unveiled thousands, if not tens of thousands of pitfalls in iOS development so I don't think anyone can argue that it represents any kind of elegance anymore, only that it is better than some other environments (which often isn't saying much). Yet this is how I earn my living, so in the end, I guess I accept it despite its (numerous) flaws.

iOS 8 Debugging Case Study

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