I've been using objective C for a while now, and I've started learning some of the lower level iPhone API's such as core audio. Most of these API's are in C which is confusing me a bit, I'm not sure where to put a lot of code and I don't know the rules, etc. Does anyone know where a good place to start learning this is?
Thanks, Darren.
You can write C inline inside any Objective C method. You can also define functions in a .c file and their prototypes in a .h file which you can then include into any ObjectiveC .m file and call from within Objective C code.
Does anyone know where a good place to start learning this is?
Buy and read "The C Programming Language". It's not very long and surprisingly enjoyable.
Read and understand Apple's C-based example code.
Browse the header files for Apple's classes. This is a great way to learn how apple sets up enums and string constants, etc.
Doing these three things won't make you an expert in C, but it'll give you 90% of what you need to be able to confidently get things done with Apple's low level frameworks.
Objective-C is a superset of classic C, which means you have access to everything C as well as everything implemented in Objective-C. You can write in both if you wish.
Related
We started a new OS X project based on Swift, only to find out that the management doesn't really like that just through the use of Swift, we cannot sell the application to users before 10.9, even if 30% of the market still has older OS X versions.
Reimplementing the software in Objective-C seems to be the only solution. As Apple advertised Swift to be binary-compatible with Obj-C, I'm wondering if a translation of Swift source code to Obj-C source code is theoretically possible, and if so, if you know about any implementation of that idea.
Couldn't find anything about this topic on the web so far, everyone seems to be searching for the other direction at the moment.
Of course it's possible. But I am afraid there's no tools to do that. You should rewrite all the codes manually.
As you mentioned, Swift and Objective-C codes can work together perfectly. So I think rewrite the codes one class/file by one should be a good way.
Apple's document Using Swift with Cocoa and Objective-C https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/BuildingCocoaApps/ should be help.
I am developing an Applescript application using X-Code and I'm having the hardest time finding answers to questions. It's tough because I'm struggling to understand how the UI elements work, etc., and most answers to those questions are written in Objective C. I have learned a little bit about how to convert Objective C code into Applescript, but in most cases I'm still not sure.
For example, this answer shows some ObjC code, but I don't know how to make use of it in my Applescript application.
Is there a resource or guide that can help me to a) understand how to use Objective C code in my Applescript app, and/or b) how to rewrite Objective C code in Applescript?
In general, Applescript can be used to automate tasks (especially repetitive ones) for any MacOS application that exposes an Applescript dictionary.
One can compile and execute Applescript from within MacOS applications written in Objective-C (via the NSApplescript class, but the other way around, one would use Applescript to call into an already existing app (or one that you created yourself) that was written in Objective-C.
It sounds like you should write the lowest level stuff natively in Objective-C and see if you can automate that from within Obj-C, or expose an Applescript dictionary (via an sdef file that gets included in the Xcode project) and then you can use Applescript to do things via your native app.
Makes sense?
It is possible to do OO programming in pure C.
Some strategies use pre-processor macros to make it easier and less error prone. Some strategies involve adding new syntax which is expanded to pure c by a pre-processor, along with a base object class and some methods for memory management.
It seems that Objective-C began as a project much like this
Do any tools exist that allow objective-c syntax to be processed to pure C?
Without having explored it, it seems do-able.
Just to clarify, I am not asking about compiling iOS code to other platforms, or asking about ports of the cocoa library to other platforms, I am wondering about ways of using oo techniques in pure-C, using Objective-C syntax and a preprocessor or precompilation step.
Portable Object Compiler. It's not capable of compiling modern Objective-C, but it sounds like it is perfect for what you're asking. Look here at a discussion of POC's shortcomings
The situation for C++ is more interesting. Cfront was the original C++ compiler that produced C code, but besides being long outdated it was commercial and cannot be (easily?) downloaded today. Fortunately, there is Comeau C/C++ which is supposedly very modern and standards compliant. It costs $50.
However, I wouldn't expect to get very readable C code from either of them (especially the full-featured Comeau).
It is possible to do oo programming in pure c?
Yes, as oo is a matter of philosophy. Look at glib and how you can do c style object: http://developer.gnome.org/glib/
Apple did it with Core Fundation: https://developer.apple.com/library/mac/#documentation/CoreFoundation/Conceptual/CFDesignConcepts/CFDesignConcepts.html#//apple_ref/doc/uid/10000122i
By the way: Do any tools exist that allow objective-c syntax to be processed to object oriented pure c?
Yeah: gcc (GCC 4.6 according to Wiki, never actually checked ;)) and clang, tools that you are usin everyday.
This is the Objective-C Runtime who make the obj-c obj-cAble, so you need libobjc.A.dylib library too. You can write obj-c in pure c code, since all message '[]', '#' directive and other obj-c stuff are converted in c after compilation.
No it's not possible, as all special (non-identifier) symbols of Objective-C can not be used as preprocessor macros. At least not with the standard C preprocessor.
Other preprocessors may be able to define macros with non-identifier names, although I don't know of any.
When talking about preprocessors in the early days of Objective-C (and also about C++) it's probably (and in the case of C++, definitively) a custom made parser that instead of outputting assembler or objective code outputted C code.
I'm looking for a library in c or objective c that does node-data visualizations similar to http://arborjs.org/
helpful answers include,
what are graphs like that called?
names of libraries that do something like that.
suggestions for implementation.
I'm targeting iOS and/or MacOS, hence c or objective-c/cocoa. On iOS the javascript version runs super slow.
Thanks!
Edit: GraphViz looks great. I'm a little concerned it may have dependencies that are GPL, and thus can't be used on iOS... looking into that now.
Actually there seems to be an Objective-C port of arborjs, see https://github.com/epreston/PSArborTouch.
This is called graph visualization and the best toolkit that I know for it is called GraphViz. It has C libraries.
That sort of graph doesn't have a particular name; not without knowing more context. So without more information, it's a "graph".
As for a library, there's an open source project called GraphViz. You'll have to dig a bit to find the drawing code, but it's in there somewhere. :)
I do not have a Mac, or an iPhone. However, the concept of taking C and making it more dynamic towards the idea of smalltalk, python or ruby is really attractive to me. I'd love to start on objective C.
Is objective C just a syntax superset of C or is it really like C. As in, can it be compiled with gcc etc..?
I do most of my programming in Ruby. Objective C seems so much more forgiving than C. You can write native extensions for Ruby in C. Can you write native extensions for Ruby in Objective C?
How can I get started with Objective C outside of owning an Mac/iPhone and having XCode?
Wikipedia says
Today it is used primarily on Apple's
Mac OS X and iPhone OS, two
environments based on, although not
compliant with, the OpenStep standard,
and it is the primary language used
for Apple's Cocoa API though it was
originally used as the main language
on NeXT's NeXTSTEP OS. Generic
Objective-C programs which do not make
use of these libraries can also be
compiled for any system supported by
gcc, which includes an Objective-C
compiler.
Objective-C today is often used in
tandem with a fixed library of
standard objects (often known as a
"kit" or "framework"), such as Cocoa
or GNUstep.
Maybe you should get a Linux vm if you are mainly running Windows and get GNUStep running.
apple contributed the objective c changes back to gcc (not that they had much choice, being GPL). So wherever you can set up gcc, you can set up an objective-c compiler.
Beyond that, the Gnustep environment can give you a bit of the flavor of the original OpenStep/NextStep environment.
Yes, you can write, compile and run objective c programs outside a MAC/IPhone
Please check the link below for details
http://www.otierney.net/objective-c.html#settingup
http://www.faqs.org/faqs/computer-lang/Objective-C/faq/
There's a difference between Objective-C the language, and the frameworks that Apple has built on top of it. Those frameworks consist of a bunch of objects which you can use in your code and are especially helpful if you're targeting the Mac or the iPhone. There are some similar objects for parts of it in GNUStep, but it's not a complete replacement for the Cocoa/etc library and especially doesn't cover anything iPhone related.
GNUStep and the Objective-C language (via gcc) are available for many platforms, and you can write your own programs that use Objective-C objects and interact with any C api from Objective-C.
Objective-C is a superset of C and so is not really more forgiving than C, but it is arguably more forgiving than C++ (an almost-superset of C). You can also mix Objective-C and C++ with GCC but that gets a little complicated, especially regarding exception handling.
For getting started and playing around with the language though, GNUStep and GCC would be a good way to go.
I don't see any compelling reason why you cannot use Objective C for native ruby extensions, except that you won't benefit much. You will still have to use the lower level C Api calls, since as far as i know, there aren't any ruby to objective-c bindings. Additionally, Objective C comes with a fairly substantial library of utility classes that, while helpful, won't easily justify their size and weight in the context of a ruby extension.
You can you this page for simple experiments with ObjC: http://www.codesign.cz/LearnObjC/