I've become very comfortable in the world of pointer-free, garbage-collected programming languages. Now I have to write a small Mac component. I've been learning Objective-C, but as I confront the possibility of dangling pointers and the need to manage retain counts, I feel disheartened.
I know that Objective-C now has garbage collection but this only works with Leopard. My component must work with Tiger, too.
I need to access some Cocoa libraries not available to Java, so that rules out my usual weapon of choice.
What are my alternatives? Especially with no explicit pointers and automatic garbage collection.
What do you mean by "component?" Do you mean a chunk of code or a library you are going to hand to other people to link into their apps? If so then it is not realistic to use any of the bridged languages at this time. While a lot of the bridges are very nice, they almost always have complications and issues that most app developers will not be willing to deal with to use a single component, especially if it involves bringing in a substantial runtime.
The bridges are most valuable to bridge other language libraries into your Objective C app. While you can write fairly complete apps using them, doing so often requires a better understanding of Objective C than simply writing an Objective C application, since you need to understand and cope with the language, object model, threading, and memory allocation impedance mismatches that occur.
This is also why many people argue that even if you are quite familiar with a language, trying to learn Cocoa using that language through a bridge is generally more difficult that learning it using Objective C.
Finally, much of the recent support for bridged languages was due to "BridgeSupport," a feature was added in Leopard. Even bridges that predate that have been migrating towards, sometimes in such a way that using the bridged language on Tiger and Leopard can have substantial differences. Also, there is currently no bridge support for iPhone, and most bridged languages will not work on it, if that is an issue.
Ultimately, if you are writing a library that is going to be linked into other apps, you need to run on Tiger and Leopard, and you need to access Cocoa only APIs I think you will find using any non-Objective C solution quite difficult.
You can try PyObjC to write Cocoa apps in python, or MacRuby if you are interested in Ruby.
You shouldn't be intimidated by Cocoa's retain/release reference counting. It's much, much easier in practice than GC fans would have you believe. The Cocoa memory management rules are dead simple, they only affect a tiny amount of your code, and even that code can be generated automagically.
Here's the trick. You encapsulate your MM code in accessor methods, and always use accessors. Xcode has built-in scripts to generate the appropriate accessors, or if you need more flexibility there are 3rd-part apps like Accessorizer.
This isn't an intrusive approach - you only need to worry about retaining an object if you're going to need to keep it for later use, and if you're going to do that you'll need an instance variable in which to keep it anyway. And, if you're using KVO and bindings, you'll need to use accessors to make sure the appropriate observer notifications are fired. Basically, if you're using good OOP and Cocoa practices, there's practically no additional thought or effort involved with memory management.
Most folks who have difficulty with Cocoa's "manual" memory management are doing so as a result of misusing it. The most common mistake is to scatter the relevant code all over the place. That means that a missing retain, extra release, etc will be difficult to find.
Try any of the Cocoa bridges listed in here http://www.cocoadev.com/index.pl?CocoaBridges
You can also try F-Script - a smalltalk dialect that is written specifically for MacOSX/Cocoa.
RubyCocoa is getting steadily more impressive, and I've seen lots of successful implementations using it. That is, of course, if Ruby's your cup of tea...
You can always use REALbasic (www.realsoftware.com). Real easy and fun to use, not free though. You can not make dylibs (or dll's) using it, but you can use dylibs and dll's in your code. And you can use cocoa libraries as well
Don't forget that you can use java as well, and i don't mean java-cocoa bridge, i mean actual java.
There's also a package from apple that provides you with access to a couple of osx features as well.
Also to comment on Shem's point, if your targeting osx 10.5 and above, you can take advantage of garbage collection.
If you want lisp syntax then Nu is a lisp implemented on top of Objective-C http://www.programming.nu/
Also, FreePascal can generate native Carbon Apps (in progress working for Coccoa)
Look at Python and wxPython (the wxWidgets in Python).
The wxWidgets have a very elegant App-Doc-View application design pattern that's very, very nice. It's not used enough, IMO. I haven't found any wxPython examples of this App-Doc-View example, so you have to use the C examples to reason out how it would work in Python.
I'd post examples, but I haven't got it all working yet, either.
.NET via Mono mono-project.com
See NObjective (http://code.google.com/p/objcmapper/) bridge to Cocoa. It provides more features than others with less overheads.
I'm looking into Mono too. Objective-C is a little too bizarre for me at this point. Too many years doing C/C++, Java, C#, Perl etc. I suppose. All these seem pretty easy to float between. Not so for Objective-C. Love my Mac but afraid it will take too much precious time to master the language.
Related
I am new to Mac/iOS development. I am coming over from C# .net. My question is should I read on Objective-C first or Cocoa? I don't want to buy two books and start reading one and find out I should have only got one book and read it.
Thanks
Curtis
Seeing as how the Cocoa frameworks were built with Objective-C, learning the language is the logical first step.
You don't need to become fluent in the language, to the point of exchanging implementations and dispatching blocks like nobody's business, all before you learn the frameworks. Indeed, such an undertaking would be folly.
At the same time, you can't learn Cocoa without a firm grasp of OOP, dynamic dispatch (messaging), MVC, and other important concepts. Some of these underlie Objective-C, some are part of Objective-C, and some are separate from Objective-C.
I say start learning those concepts, including the basic portions of the language, and then pick up the framework before you get too far into it. Like Regexident said in their comment on one of the other answers, you pretty much can't practice Objective-C without using Cocoa anyway, so it won't be long before you need to start into the framework to in order to practice the language—at which point you'll be practicing with both.
Relevant Apple documentation:
Object-Oriented Programming with Objective-C
Learning Objective-C: A Primer
Cocoa Fundamentals Guide
The (full, gory details of the) Objective-C Programming Language
If you don't already know C, start there. As with Objective-C, you don't need to become a full-blown C guru, but you do need to understand pointers, declarations vs. statements, how function calls work, the differences between the primitive types, and other basic concepts.
Objective-C is just a superset of C. All the Cocoa books that I've seen introduce Objective-C in the first part and then go on to describe how to use the frameworks. I'd recommend just getting a Cocoa book, just leaf through it and make sure the Objective-C primer in it is meaty enough for you.
I believe there is a lot of good information in the various answers here (especially #Peter Hosey's), but I do want to make sure we're not confusing the OP.
You can't practically learn ObjC without learning Cocoa today. It's like learning C# without learning .NET. You absolutely should focus very early on the patterns and underlying concepts of Cocoa (like MVC, as PH notes). But you'll get that best by working through things that teach you practical iOS or Mac development techniques rather than working through something that tries to provide a more "pure ObjC" experience such as writing command-line apps (though even Foundation is part of Cocoa, so even then you can't escape it).
The key lesson here is that I recommend new students focus on resources that teach them the whole process they need to develop for iOS or OS X. It's worth learning Xcode, ObjC, and Cocoa(Touch) together, along with MVC, target/selector, and the other critical patterns, rather than trying to take them one at a time.
PH is absolutely correct that you don't need to learn all of ObjC in one go. You can do a lot of development and never use blocks or KVO for instance. (That may change in future versions of iOS, but it's still true today.)
Years ago wanting to write Mac software and having loads of experience with Java WebObjects I tried the java bridge but decided to bite the bullet and learn Objective-C (fortunately since I would have hated having my software deprecated with the bridge). Later I fooled around with RubyCocoa. I learnt Ruby (found it interesting indeed), but found out the hard way that the bridge was far from mature or stable and at the end I ended porting the code back to Objective-C.
Since years have passed, I'm wondering if it is worthwhile investing some time with MacRuby, or even learning Python to use PyObjC. As much as I like Objective-C, I recall being way more productive with the Ruby bridge when it didn't crash. I just would hate investing time to end up with crashy software again.
I would say MacRuby is the way to go if you want to try one of the bridges. It's being developed by Laurent Sansonetti, who's a Senior Software Engineer at Apple working on Ruby.
It's quite functional now, and integrates nicely with the native frameworks. Worth a look, particularly if you already have Ruby experience.
If you want to learn Cocoa programming, ignore the bridges. They will only make writing Cocoa applications more difficult and you will waste a bunch of time getting up to speed.
Specifically, you will need to learn Objective-C to be able to understand both the APIs and design patterns of the system frameworks. Furthermore, all of the documentation and tools are written specifically to support Objective-C.
The bulk of your time in learning Cocoa programming will be spent on said APIs and design patterns; the actual language part is relatively small, by comparison.
Note also that the bridges necessarily incur an impedance mismatch in an attempt to map not-quite-the-same functionality from one language to another.
Frankly, if you know Ruby, then Objective-C should be trivially easy; the object models are very similar.
My personal opinion is use ObjC for Mac native apps.
Use Ruby/Python where they supposed to work good natively without unreliable interfaces with questionable support.
Here is why it is NOT a waste of time. In some cases, Ruby and Python have awesome and well developed libraries that are not available in Objective-C and would not likely be.
That is one of the best use cases.
Example: you wouldn't want to reimplement Rails in Objective-C, (some people might) but you could easily use it, parts of it to power a Cocoa app with MacRuby.
Well MacRuby is dead. There is the commercial RubyMotion.
There is still PyObjc, RubyCocoa and mruby.
One of the other intriguing use-cases is to provide script ability that doesn't stink like AppleScript and OSA.
There are valid reasons.
Well, I think I have enough knowledge of cocoa that I can go learn another thing. What would you recommend learning after learning cocoa? (Ex. Core animation, OpenCL, core data)
I really depends what your goals are. If you want to stick to Objective-C, dive into Cocoa Touch if you haven't already. I'd also suggest checking out frameworks such as MacRuby if you want to stick to developing Mac apps, it is pretty sweet.
If you want to go somewhere totally different, I've been messing around with Rails and Android a lot recently.
Learn LISP.
It is fundamentally different from pretty much every other programming language there is. It will force you to think of problems in new ways. Even if you never ever will use LISP in a real world project (I never did) you will become a much better programmer.
Anyone who wants to call themselves a programmer should known about (spent at least a full week with):
C - to know the heavy lifting and how it actually works.
LISP - to understand functional programming.
Smalltalk/Objective-C - to understand real object oriented programming.
Prolog - to understand logic programming.
C++, and any language that derives its OOP design from it, is just C structs with function pointers. Yes Java and C# I look at you too.
Learning PostScript is a good way to broaden your understanding of the drawing model also used by Quartz and AppKit, and can be useful for prototyping your drawing code.
Learn another language. Maybe C/C++ since they are similar. Or maybe C#. Or you can try something completely different such as python, pascal, D or VB.
depends what you aim for
but if you are not strong in C/C++ I would suggest that. A) its what cocoa is based on B) if you want to port your code to other platforms, usually you'll have a good chance of reusing directly the C/C++ withou a lot of changes.
(Ex. Core animation, OpenCL, core
data)
those are just tools, if you want to specialize in iphone then its good practice to look up the various feature, look at the examples and then implement a little example for yourself.
otherwise if you have no precise goal you can also go to the bookstore and pick a random book ^^
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I have heard mention of Objective-C but I have never used it myself. I was curious what everyones opinion of it was in general and also in relation to C++. Are there any types of projects where it would be more useful or less useful?
Like many others I've just started looking at Obj-C due to iPhone. I've done a lot of C++ and C# and from what I can see Obj-C has a basically different approach to OO in that it adds Smalltalk-like messaging to C. Like C++ it's basically still C-compatible but the OO extensions let you send any message to any object. In that sense it's not statically typed like C++ and C# where the things an object can do are tied to the class it is. In Obj-C you can send a message to an object even if it doesn't support it. The object can then forward it if it doesn't know what to do with it.
The really cool thing is that you can add interfaces (protocols) at runtime and you can add your own handlers that intercept and hide message handlers for existing classes.
All in all there's a lot more flexibility when it comes to message handling, more like what you would do in Ruby or Smalltalk. Whether it's a good idea to have this type of OO grafted onto C or not I can't tell yet, in some ways the C++ approach meshes better with the original idea of C but on the other hand the Obj-C OO approach is more what OO purists like.
From "Some nice features of the Objective-C language":
Classes are objects
Dynamic typing and optional static typing
Categories
Message sending
Expressive message syntax
Introspection
Dynamic run-time
Automatic garbage collection
C inside
C++ fluent
Simplicity
Access to Apple technologies
I find objective-c's syntax a little cleaner than c++'s although I know I'm in the minority here
Objective C's OO features use dynamic typing instead of static (compile-time) typing. That's the major difference in the approaches of the two languages - whether it's an advantage or not depends on your opinion about static vs. dynamic typing.
My opinion is that the syntax of Objective-C is a little "weird" at first, particularly if you are coming from a C/C++ background (as I did). If you plan to write apps for the Mac or iPhone, Cocoa development is the way to go. I had an opportunity to do some development on the Mac for about a month this Spring and opted to write it in C++ using the Qt libraries since I was quite familiar with those and time was of the essence.
If you have a Mac, give it a shot! There is a LOT of info out there on it and there are some good tools for development.
Part of what makes Objective-C so great isn't the language (although that is a big part ot it), it's the Cocoa (or CocoaTouch) framework that goes along with it (at least for 99% of objc users ;-)
In practical terms, I used to be a C++ programmer back in the old "classic" Mac days. Switching to Objective-C, Cocoa and Mac OS X i found I became much more productive. Hard to say exactly how much more productive, but 50% to 100% feels right.
If you're running Linux you can install GNUStep which provides pretty good compatibility with Cocoa. This can get you started on Objective-C/Cocoa development without owning a Mac. The best resources for learning Objective-C [in my opinion] are with Apple.
http://developer.apple.com/referencelibrary/Cocoa/index.html
Well, If you are coding for the some platforms like the IPhone, Objective-C is required. Objective-C also uses dynamic(run-time) typing, which many people prefer over static(compile-time).
WebKit was originally a C++ project (khtml from KDE) that was later adapted by Apple to be more compatible with the Cocoa-environment and thereby got its Objective-C layer.
It is more dynamic than C++ and heavily influenced from Smalltalk. I don't find it "better" than C++ - on the contrary, but some people do.
For Mac and iPhone development, it is definitely better. The latest version has a GC, so if you like that, you'll probably like it better than C++.
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Do I really have to learn Objective-C to develop solid Mac Apps?
As Mac users tend to use only applications that have a nice (native) GUI, i don't think that Mono and GTK+ or any Java GUI (Swing) will fit their needs.
There are projects like Cocoa#, PyObjC and RubyCocoa, but are they ready for primetime?
So do I really have to learn Objective-C ?
I would prefer a dynamic language.
Objective-C is a dynamic language, as far as the Objective-C parts go. Here's a little summary article: http://www.macdevcenter.com/pub/a/mac/2003/04/28/objective-c.html
The syntax is scary at first, but it grows on you. I suggest biting the bullet and slogging through it.
If you want to work at a "real job" doing Mac programming with other people, you're going to need to know Objective-C (in my opinion, anyway).
I think the short answer is yes, you need to learn Objective-C.
The Python and Ruby "bridges" work, but it's not what Apple is pushing or using itself. A few years ago there was a Java bridge to Cocoa but that's now deprecated. Who knows what will happen to the non-ObjC languages?
In any case, Objective C is pretty dynamic. Not in the way that Ruby/Python are perhaps, but it's certainly not like C++.
Short answer: YES :)
Our first app was built in Python, using the PyObjC bridge. From experience I can tell you that to build an application with a bridge you need to learn:
The idiosyncrasies of the bridge
To read and write code in the bridge language (Python in my case)
To read code in Objective-C (All useful sample code is in Obj-C)
To write pseudo-code in Objective-C (if you ever want to ask questions on a mailing list or likewise)
Cocoa
Of all those things to learn, Cocoa is the biggy. It's where the really interesting stuff comes in and the thing you really need to wrap your brain around. After working on this PyObjC project, it's become pretty easy for me to code in Obj-C, even though I had no prior experience coding in C.
So my advice is: Focus on learning Cocoa, and use the language that's most suited as a tool to do that (Obj-C). If you ever find a particular reason to use a bridge, such as having a need for an ORM that can deal with networked SQL, etc. you can apply around 90% of what you learned writing your first Obj-C/Cocoa app(s) in the bridged project.
Finally: I don't really understand the resistance many people who're new to the platform have to learning Objective-C. Isn't it exciting and gratifying to learn new stuff and build the best possible things armed with this new knowledge?
You definitely need to learn Objective-C even if you choose to use one of the bridges. Apple has already shown by their treatment of Java that they're not really interested in providing huge amounts of support or backwards compatibility to the use of Cocoa through anything but Objective-C.
So use one of the bridges, if you like, but have a firm grasp of the Objective-C runtime and the bridges so that you can manage them yourself, if need be.
Do I really have to learn Objective-C to develop solid Mac Apps?
Currently, yes.
As Mac users tend to use only applications that have a nice (native) GUI, i don't think that Mono and GTK+ or any Java GUI (Swing) will fit their needs.
Correct.
There are projects like Cocoa#, PyObjC and RubyCocoa, but are they ready for primetime?
Cocoa#: I don't know, as I don't use C#.
PyObjC: Sort of, but Cocoa in Python is a bit of a hack, since Python isn't Smalltalky enough.
RubyCocoa: Maybe. I'm waiting for MacRuby to mature, though. See also:
Jens Alfke on MacRuby
Jesper on MacRuby
There are a small number of successful Cocoa apps written in bridged languages, so you don't necessarily need to use it that much, but you do need to learn it. People who try to learn to write Mac OS programs in bridged languages do themselves a huge disservice. The bridged languages are great tools, but they are the sort of things that allow someone with a knowledge of the bridged language and Objective C to become extra productive, not skip learning Objective C.
In order to use something like PyObjC or MacRuby effectively you need to really have a good understanding of how the native runtime works to deal with all the impedance mismatches that can occur between the bridged language and the Objective C runtime.
Short answer is yes, longer answer is "you can use Objective-C++." Either way you're going to have to learn at least some of Objective-C. Once you start digging into Cocoa (the framework for building Mac OS X apps), the Xcode tools, and the Apple Human Interface Design guidelines, you'll realize that Objective-C is the way to go.
Not only you have to know Objective-C (the easy part), you must be very comfortable with plain old C. That's in my opinion the biggest challenge for most people.
If you already know C, Objective-C is pretty easy to learn.
Ruby and Python are both viable for "real" Mac apps. ADC has a few articles on the topic. MacRuby looks like it will be replacing RubyCocoa.
I would still recommend learning Objective-C though. Most of the example code you find will be in Objective-C and the books tend to be Objective-C (though the Pragmatic Programmers have a RubyCocoa book in the works. Most Cocoa apps are written in Objective-C.
And Objective-C is dynamic. Take a closer look at it, it isn't nearly as intimidating as people think. It's Cocoa that tends to have the steeper learning (or unlearning) curve.
No you don't have to learn cocoa however it is worth looking at because it is an incredibly powerful api and very well documented, if you already know C then its very easy (honestly it is - i know it looks daunting syntactically).
The problem with the bridged approach on OS X is it seems to be very immature and only really designed for people who are prepared to read the documentation associated with the main cocoa api.
In all honesty if you know c you will pick up the basics of obj-c with a book, the one by Arron Hilligas (spelling?!?!) is superb.
If you try hard enough, you can go about producing software without using Objective-C that has the potential to be great except for the fact that at the end of the day it won't be very good. You will spend more time trying to harangue a language into doing something that it isn't the absolute best at. At WWDC I wore a shirt that said "Learn Objective-C or Retire" which didn't go over too well with some people who still held dearly onto the last threads of Pascal's life, but the point is altogether true - Objective C is where it's at on the Mac and to pretend otherwise is to do yourself a disservice.
Having said that, you should definitely not rule out the bridges on the platform for extending your application - Bill Bumgarner is quick to point out how much power the Twisted networking framework provides to Cocoa applications via the PyObjC bridge.
Not programming in a scripting language turns out to not be so bad when you're using XCode. The GDB integration is very good; I'm primarily a Perl guy, and I find the XCode debugger very nice and very easy to use.
The "fix" feature will really surprise you with how usable it is. Imagine finding a bug in your ObjC code, fixing it, and then telling the debugger to continue on. It actually works in a lot of cases.
Try ObjC. You may find you like it a lot better than you think you will.
"have to", well... technically, no.
Since most Mac app jobs are done thro ObjC (for a very good reason I might add), I wouldn't kid yourself and learn it.
Hell no. You can use a number of languages to make a nice GUI with. It just depends on what's the usual/easiest solution for the platform. In Mac OS X's case, Objective-C and AppKit are pretty easy to use choices. However, I use REALBasic sometimes, and that allows cross platform development (and, of course, a performance hit).
So really it depends on how much work you want to put into it. You should learn Objective-C if you want to really do serious Mac development. But you can get by without it....
No. While Apple is strongly pushing Cocoa, Carbon is still supported. It uses plain C instead. As for good-looking GUIs, just use Interface Builder.
However, I must say that Objective-C is a great language. It is really easy (it was my first language) and very powerful.
In general yes; but even if you (correctly IMHO) ruled out Mono, GTK and SWING because they don't fit well in the GUI, try Qt. it's REALLY respectful of Mac GUI standards (HIG: Human Interface Guidelines), and can be equally programmed on C++, Python and Java. the last version is cocoa-based and 64-bit capable.
the only thing missing from Qt that you'd get from Objective-C is those awful non-HIG-compliant modern Apple applications (yeah, Aperture and Final Cut, I'm looking at you!)