The rejection of a recent edit I suggested gave me doubts about something I thought I knew on Objective-C.
I've lived under the assumption that the UIViews are part of iOS, that iOS is a descendant of Objective-C and that Objective-C has no default kits with any views.
I've tried some Google and Stack Overflow searches, but the results didn't seem trustworthy and were mostly about UIViews. Wikipedia seems to mention nothing about this .
Does Objective-C have views? Or is that, as I assumed before, a common misunderstanding?
The problem that I see is that iOS is NOT a descendant of Objective C.
iOS is the operating system (like Windows Linux OSX) whilst Objective-C is a programming language albeit one that most iOS and OSX apps are written in. However there are iOS apps written in Python and other languages,
iOS as such does not have views - these are part of the Cocoa-touch framework which is a set of libraries that run on iOS and can be called with Objective C code. Although in practice for the programmer the difference between calling code in iOS and Cocoa touch is not really clear if you are only writing for iOS devices, the split is clearer in OSX where you can write code just using OSX calls or can use Cocoa frameworks.
As noted the views are part of the Cocoa touch framework. This can be called by any language including Objective - C. Most languages do not include the ability to write GUIS as part of itself they usually make use of separate libraries to do this. For example Objective C has no GUI libraries itself but has had Cocoa touch written for iOS, Cocoa and Carbon (although that mainly uses a C binding) for OSX and GNUStep for Windows and Unix like OSes (and historically NeXTStep, OpenStep, Rhapsody, basically earlier versions of Cocoa, on various OSs and Stepstone's ICPak 201)
Objective-C is the open source programming language. UIKit(iOS) and AppKit(Mac OS) are what provide the visual elements - and this is not open source.
Objective-C itself doesn't have a UI, that's provided by other frameworks.
From what I have understood obj-c's views are part of the UIKit framework : check here
which is designed for constructing GUI applications on the iOS.
I don't think you can use this framework in other obj-c applications but on iOS. Probably there are other frameworks that have views which can be used.
Edit: And yes, good point by #Mark that you are confusing the Operating System with the Programming Language
Related
This question pops up quite often here, even if just implicitly when users mistag their iOS questions. So, what’s the difference between Xcode, Objective-C and Cocoa?
Objective-C is a programming language. It could be said that it’s just a description of what valid Objective-C programs look like and what they mean. If you have a source code listing written in Objective-C, you need an interpreter or a compiler to put the listing to work. Languages like Objective-C are usually compiled, so most people use a compiler (like LLVM). Objective-C is almost exclusively used to develop for iOS and OS X, but there are other uses, too – as an example, some people write Objective-C for Linux.
You can use a text editor to write the sources and a compiler to turn them into an actual programs, but with modern technologies there’s much more to take care of, so that there is another program to make your job easier. These are called Integrated Development Environments, or IDEs. An IDE offers you a convenient way to edit the sources, compile them, debug the resulting programs, read the documentation, and many other things. Xcode is one such IDE. An important observation here is that Xcode does not compile your sources itself, it just calls the standalone compiler (LLVM). And Xcode is not the only IDE you can use to develop Objective-C apps – there’s AppCode, for example.
Writing iOS or OS X apps from scratch each time would be very time-consuming. That’s why Apple provides the developers with a good set of libraries. The libraries are simply a huge amount of source code written by Apple, and this source code takes care of most things that apps have in common. These libraries are called Cocoa.
Now, if you can’t figure out how to extend a class, you are most probably talking about Objective-C. It doesn’t have anything to do with Xcode or Cocoa, you could be very well writing some GNUstep code for Linux using Vim as an IDE and GCC as a compiler. On the other hand, if your Xcode build process fails because of some mysterious setting, or if you’re trying to build a static library in Xcode, that’s clearly an Xcode issue. And if you can’t figure out how to use some NSObject facility or the NSFileManager class, that’s Cocoa. (But it doesn’t have to be Xcode-related, as you could use AppCode or TextMate as your IDE!)
Originally available on my blog. Feel free to link to the blog post or this question when retagging or explaining the difference.
Xcode is the integrated development environment (IDE)—the application—that developers use to write software for iOS and/or OS X. It includes the editor, the build system (determining what to build to produce the desired target), and quite a few other things.
Objective-C is the main language that developers write such software in. They may write bits of it in pure C, use C++ or combine it with Objective-C (producing Objective-C++), or write some or all of the program in another language entirely, such as MacRuby, Java (with j2objc), or C# (with MonoTouch).
Xcode includes the Clang compiler, which turns code written in Objective-C, C, and a few other languages into executable code. Most error messages come from Clang, and Xcode relies heavily on it for search indexing, syntax highlighting, and name completion of Objective-C code.
Cocoa and Cocoa Touch are application frameworks. Each one is a suite of many individual frameworks (libraries stored in folders named blahblah.framework), such as:
Foundation (both): General object-oriented utilities, including NSString, NSURL, NSFileManager, etc.
Core Foundation (both): Mostly the same thing, but different, mainly in having a C-based API rather than Objective-C
Application Kit (Mac): Application and windowing framework
UIKit (iOS): Application and windowing framework
Core Graphics (both): Drawing
Core Animation (both): Sprite-management and animation framework
(and many, many more where they came from, especially on the Mac)
So:
You can use a framework besides Cocoa or Cocoa Touch, but you'll have to have some Cocoa/Cocoa Touch code, at some level, in order for your application to talk to the system, receive events, draw, etc. Frameworks that specifically target Mac and/or iOS will include the relevant wrappers for you, at varying levels of quality.
You can use a language besides Objective-C, but you'll have lots of syntactic awkwardness, as most of Cocoa and Cocoa Touch are designed for Objective-C's unique syntactic features (particularly selectors).
You can use an editor besides Xcode, and you can even use a build system besides Xcode (such as make), but Apple's App Stores expect apps built a particular way (especially with regard to code signing), so unless you're not targeting the App Stores, any other build system has to replicate what Xcode does or risk its users getting rejections.
A clear mistake is failing to differentiate Xcode from everything else. Xcode is the tool you are using to program in - to edit code, run code, etc. So if you are having trouble with the tool (e.g., the window doesn't show you your code properly, or you're having trouble drawing your interface, etc.), that's an Xcode problem.
If you don't understand why your code doesn't work, you're probably having an Objective-C problem or a Cocoa problem. But you won't necessarily know which.
It's an Objective-C problem if the root of your trouble is that you don't know how the language works (e.g. you don't know what the asterisk is for, or that declaration is not instantiation, or that messages to nil do not error out but don't do anything either).
It's a Cocoa problem if you don't grasp the delegate architecture or how a view controller works.
But my experience of the way people pose questions is that you may be ignorant of which of these you are ignorant of. I don't mean you personally, I mean all of us. This can make it difficult to pose the question properly because you don't know what exactly it is that you don't know — if you did, you'd know it and you probably wouldn't be having a problem (you'd be fixing the problem and on to the next thing).
It appears the language is the same for either device ios or mac os on a mbp, but if I learn Objective-C in a tutorial, won't I also need to learn cocoa or cocoa touch to program effectively?
I'm not sure how to start on my path of learning to program an ios device. I know I need to learn objective-c and that appears to work on all apple products. Then do I move to cocoa touch for ipad and iphone? What comes after objective-c?
The type of project is akin to a web app but native objective-c app instead. Have ui, buttons, the app hits some back end location, returns data, I put it on that same ui. Only, as stated, use objective-c and whatever framework and library to do it (that's my dilemma. I dont know what to do next after objective-c).
thanks.
Cocoa and Objective-c go hand in hand. For getting started, I would suggest going over some old WWDC footage and following some of the examples there.
As far as Cocoa and Cocoa touch are concerned, they are very similar in many aspects, same name conventions, similar structure, etc. Learn one, and you can easily pick up the other.
#craig adds:
I would further this answer by also mentioning that Objective-C is a programming language, while Cocoa/Cocoa Touch are collections of frameworks that are provided by Apple, and used by developers to add functionality to their programs. (Which are written in Objective-C.) The Cocoa frameworks contain various UI components like buttons, table views, sliders, etc. in addition to various fundamental classes like NSString and other text- and graphics-based APIs
I started my learning by watching thenewboston's xcode tutorials:
you can begin with this one
Good luck :)
I prefer books for some strange reason and I found that the Apress series of IOS development is really good. The book goes through developing iPhone and iPad apps using all kinds of Cocoa libraries. There's a lot of good books out there on the subject; I would go find one that looks like it would suit your needs.
I would like to write an app for the iPad but I can't stand Objective-C.
Is there a language generator that would spit out Objective-C but let me write my iPad application in another language?
I've heard a little about MacRuby and am curious whether it could be used this way. Any other similar projects in other languages?
C# with MonoTouch.
JavaScript with Appcelerator Titanium.
Flex with ELIPS Studio 3.
Python with PyObjC (for jailbroken iPhones though).
Apparently Lua is an option.
John McIntosh uses Smalltalk on the iPhone. For instance, his Mobile Wiki Server app.
No computer anywhere (well maybe some) cares what language you write your programs in. Heck, you could hand-write machine instructions if you were patient (and crazy) enough. As long as you can figure out how to interact properly with the system call interface and the ABI, you can do whatever you want.
You could use Corona, Torque, or Unity. These all have advantages and disadvantages compared to using the standard Objective-C SDK, but really, if it's about the language itself, it's hard to see how you would be better able to "stand" the languages supported by these three than Objective-C.
First of all, is this possible?
If so:
What challenges would I encounter in making an XCode imitation for iPhone/iPod development for Windows or Linux?
I was thinking about using gcc as the actual compiler for the objective-c and (VB).NET for the IDE. Will that work?
It doesn't need to compile to iPhone OS until it is to be tested on the device or submitted to the app store. Perhaps it will be easier to compile to the local OS format (Windows or Linux) until "prime-time".
Is this concept possible? Comments? Ideas of how to implement?
If you wanted to support all of UIKit and Cocoa Touch, the problems would be insurmountable. You'd spend 2 years trying to get off the ground and then give up, while everyone else had fun developing apps for the iPhone and iPad and other devices. You would regret even trying it.
But if you wanted to create your own framework for making iPhone apps, built immediately on top of OpenGL, it might be possible. You would create a simulator that renders to an OpenGL view, and the final app would also render everything in an OpenGL view, touching none of UIKit. You would use pure C, or some robust cross-platform language like Lua, compiled or even interpreted. Incidentally, that's more or less how the Corona framework does it: built on top of OpenGL, touches little of the iPhone SDK, uses compiled Lua. They developed their own simulator, which only runs on OSX, but could probably relatively easily be ported to Linux.
You could even use Objective-C as the language, and make available a carefully chosen subset of the Cocoa API's by using (the iPhone compatible parts of) GNUstep Base. Then users could use standard classes like NSString.
Still, all of this is mostly interesting as a thought experiment, unless you got a team together to work on this as an Open Source project. It's harder than you think. Your simulator wouldn't be able to emulate the way that memory warnings are generated on the iPhone, for example.
If someone wants to develop iPhone apps on Linux, it makes more sense to just write the whole app in C/C++ using OpenGL, and then basically just smack that code onto a vanilla iPhone OpenGL project. That's the fastest path. The next possibility would be to use another language, which is also not too hard. But an "iPhone IDE" on top of that would be little more than putting an iPhone-like frame around the OpenGL view in Linux.
Actually, Felixyz touched on something your should take a look at. See: http://www.gnustep.org/ . They have binaries for just about every variant of *nix, OS X, and windows. The site claims "GNUstep seeks to be source code compatible with Cocoa and OpenStep, it can thus be used to develop and build cross-platform applications between Macintosh (Cocoa), Unix and Windows." It would be a good jumping off point for such a project,
I doubt all OSX's functionality is covered by GNUStep, but it's a start.
I'd imagine to develop iPhone/iPod apps on an alternate platform, you'd need to get Apple's includes (Legality is likely to be an issue), and apply all their toolchain patches, plus a million other things I'm probably overlooking.
What would be a better project is implementing the missing functions in GNUStep to support OSX apps seamlessly under the host platform. Maybe then you could run xcode native on your desired OS.
It seems that Cocoa seems to be the main platform for Objective-C. GCC (which Xcode uses) supports Objective-C so it must be available on a wide range of platforms.
Are there any notable cross-platform projects that use Objective-C but not Cocoa (or its open source cousin GNUStep)? Is it really used outside the Apple ecosystem?
Objective-C has also been popular in the scientific and financial services communities. There are still many Objective-C based applications deployed in banking, mostly on the trading analysis front. A friend works on a nearly million line of code Objective-C based analysis and trading engine for which they have written their own class hierarchy from scratch.
At one point, one of the more popular Linux window managers was written in Objective-C. That was a few years ago and may no longer be the case.
The LLVM compiler also compiles Objective-C, including having full support for Blocks. It is quite portable, too.
There is also David Stes's Portable Object Compiler. It compiles Objective-C to C and uses a class hierarchy that is based quite directly upon the original ICPak class hierarchy from StepStone.
It seems what you're asking is if Objective-C is ever used without Cocoa, or GNUstep, or Cocotron, or any API like them.
The answer is basically no. Without an API like Cocoa (or GNUstep, etc.), Objective-C isn't very useful. For example, without NSObject, retain and release wouldn't even exist. A ton of very important features are built into these APIs, so it's somewhat pointless to use Obj-C without one of them.
Yep, there sure are. The one I can think of from the top of my head is Cocotron. An effort to port AppKit to Windows.
http://www.cocotron.org/
Aside from that, Objective-C can be used on any platform that gcc will run on. You won't have the wealth of frameworks that are available in Cocoa on OS X or the iPhone, although as you mentioned, GNUStep does a pretty good effort.