xcode iconIn support of today's extensive list of software releases, Apple has also pushed out the final public version of Xcode 4.2, now available through Apple's developer channel and on the Mac App Store. Xcode is Apple's package of developer tools for creating both OS X and iOS applications.

What's New in Version 4.2
- Includes SDKs for Mac OS X 10.7 Lion and iOS 5
- Storyboards let you design multiple iOS screens, and define the segues among them
- Automatic Reference Counting (ARC) saves you from manually managing retain/release
- iCloud entitlements are automatically enabled for Mac and iOS apps
- OpenGL ES Debugger graphically analyzes your OpenGL scene directly within the IDE
- Apple LLVM compiler supports C++11 features and the LLVM libc++ standard library
- Older iOS Simulators and device debugging symbols are downloaded on-demand

Xcode 4.2 requires OS X Lion and is a free download on the Mac App Store.

Top Rated Comments

HiRez Avatar
128 months ago
Is this similar to Garbage Collection?

It's better than garbage collection. GC is run-time technology and can have a dramatic negative effect on performance. Furthermore, the performance cannot be relied upon to be constant (CPU usage can spike when the GC is sweeping), and since you don't know beforehand when the GC is doing its business, bugs can be harder to track down (objects may disappear at unknowable times).

ARC is a compile-time technology. It inserts retain, release, and autorelease messages just as you would, then optimizes out redundancies before the binary is built. It simply uses the same well-defined memory management rules that you would except it doesn't make mistakes as a human can. There is no run-time penalty.

The biggest disadvantage for ARC is it can't detect cyclical references like a GC can, and that's why it includes the __weak type identifier. So you need to be a little careful for those situations, but overall it's a better technology than GC, which is why GC in Xcode will be going away in favor of ARC, at some point.
Score: 2 Votes (Like | Disagree)
DESNOS Avatar
128 months ago
ARC here I come! Good riddance manual memory management (for the most part)!
Score: 2 Votes (Like | Disagree)
gnasher729 Avatar
128 months ago
+1. I <3 ARC, but weak references are critical and the existence of incompatible code is irritating. Hopefully we'll get an SDK which is fully-compatible with ARC in Apple's next OS release, at which point we could make a clean break.
Actually, there are two kinds of weak references: "Safe" weak references that change to nil when the referenced object goes away, and "Unsafe" weak references that don't change to nil automatically. Both are "weak" technically weak references. Both work as "weak" references in 10.6, but the automatic change to nil doesn't happen in 10.6. So you can't rely on that if your code should run on 10.6.


Is this similar to Garbage Collection?

It's not a delta update. A hefty installer instead... (1.68 GB if you have 4.1)
No. It is the same old retain/release/autorelease thing, except that you don't write the statements anymore, but the compiler does it for you. The effects are: 1. Your code will be correct, because the compiler doesn't forget to retain or release an item when it should. 2. Your code may become faster, because the compiler optimizes unneeded retain/release away, implements autorelease pools faster, and uses specialized code instead of Objective-C methods. 3. If you have code that is so convoluted that the compiler can't figure out when to retain/release objects then it doesn't compile and you'll have to fix it. Most likely your code was broken anyway in that case.

Compared to Garbage Collection, your memory footprint will be lower.
Score: 1 Votes (Like | Disagree)
PR. Avatar
128 months ago
just tried. seems the answer is no.

Damn, thanks for checking

*rages* :mad:
Score: 1 Votes (Like | Disagree)
kainjow Avatar
128 months ago
Should I continue to download from the Dev Center or grab the App Store version?

I'm not sure if the Lion version is available on on the dev center. I downloaded it from the App Store and it went along fine. My coworker is downloading the SL one from the dev center and it's taking forever.
Score: 1 Votes (Like | Disagree)
ethana Avatar
128 months ago
Yes, ARC with Xcode 4.2 is HUGE for developers. If you are an iOS developer, look into ARC! It will save you from so many headaches from now on.

Yes, iOS 5.0 or greater is required for your binaries to use it.
Score: 1 Votes (Like | Disagree)

Top Stories

Pro Display XDR Yella

Apple Working on External Display With Built-In A13 Chip

Friday July 23, 2021 9:37 am PDT by
Apple is developing an external display that includes an A13 chip with Neural Engine, according to a new rumor from 9to5Mac. The A13 chip with Neural Engine would presumably serve as an eGPU, though details are light at this time. Having a CPU/GPU built into the external display could help Macs deliver high-resolution graphics without using all the resources of the computer's internal chip....
iOS 14 on iPhone feature emergency

Apple Releases iOS and iPadOS 14.7.1 With Fix for Touch ID Apple Watch Bug

Monday July 26, 2021 9:48 am PDT by
Apple today released iOS and iPadOS 14.7.1, minor bug fix updates that come just a week after the release of iOS 14.7, software that introduced new Apple Card features and support for the MagSafe Battery Pack. The iOS and iPadOS 14.7.1 updates can be downloaded for free and the software is available on all eligible devices over-the-air in the Settings app. To access the new software, go to...
discount m1 macbook yellow

Deals: Shop Record Low Prices Across Apple's Full MacBook Pro and MacBook Air Lineup (Up to $499 Off)

Friday July 23, 2021 8:23 am PDT by
Apple's MacBook Pro and MacBook Air lineup is seeing all-time low discounts across the board today, including the 2019 16-inch MacBook Pro, 2020 13-inch MacBook Air, and 2020 13-inch MacBook Pro. Note: MacRumors is an affiliate partner with some of these vendors. When you click a link and make a purchase, we may receive a small payment, which helps us keep the site running. 13-Inch M1...
iphone 12 pro gold

Report: iPhone 14 Pro Models to Feature Tough Titanium Alloy Chassis

Monday July 26, 2021 1:12 am PDT by
Next year's "iPhone 14" series is expected to feature high-end models with a new titanium alloy chassis design, claims a new investors report by JP Morgan Chase. According to the report, the use of titanium alloy will be one of the biggest changes to the case design in the 2022 iPhone series, and Foxconn will be the exclusive manufacturer of the titanium frames for the high-end models....
FaceID iMac REREREREMIX

Gurman: Face ID on the Mac Coming Within a 'Couple of Years'

Sunday July 25, 2021 7:09 am PDT by
Apple plans to bring Face ID to the Mac within the next "couple of years," respected Bloomberg journalist Mark Gurman said today in the latest edition of his Power On newsletter. In the newsletter, Gurman says that he believes Apple's ultimate goal is to shift all of its products to Face ID, including the lower-end iPhones such as the iPhone SE and the iPad Air, which feature Touch ID....
airpods 3 gizmochina Feature

AirPods 3 Rumored to Launch Alongside iPhone 13 at Expected September Event

Friday July 23, 2021 12:54 am PDT by
The third-generation AirPods will likely launch at the same event revealing Apple's upcoming iPhone 13 lineup, according to a report from DigiTimes, which makes the claim citing sources familiar with the matter. The report as a whole echoes previous reporting that production of the third-generation AirPods will kickstart in August, meaning a launch shortly after can be easily expected. DigiTi...
imac with accessories

Larger Redesigned High-End iMac Rumored to Launch Next Year

Monday July 26, 2021 3:45 am PDT by
Apple's larger redesigned iMac will arrive sometime in 2022 rather than later this year, according to the leaker known as "Dylandkt." On Twitter, Dylandkt claimed that Apple's "high end iMac" is not expected to release in the fourth quarter of 2021 alongside Apple's "M1X Macs" – a reference to Apple's redesigned MacBook Pro models – because "Apple simply does not want their devices to...
apple bitcoin hack

Is Apple Really Buying Bitcoin?

Monday July 26, 2021 3:07 am PDT by
A large number of websites and posts on social media are stoking rumors that Apple has purchased $2.5 billion worth of bitcoin in the company's first move into cryptocurrency, but is there any validity to the claims? Many people are citing the fact that Apple was looking for a Business Development Manager with experience in alternative payments, including cryptocurrency, earlier this year as ...
apple mac business page

Apple Shares 11 Reasons Why Business Users Should Choose Macs

Monday July 26, 2021 11:35 am PDT by
Apple today updated its Apple at Work website with a new section dedicated to the Mac, which offers up 11 reasons why "Mac means business." On the webpage, Apple highlights the M1 chip as the number one reason why business users should choose a Mac, offering up an M1 overview [PDF] that explains the benefits of the M1 chip. The information isn't new, but it does provide a look at all of...
magsafe battery pack iphone 12 mini

Top Stories: Hands-On With MagSafe Battery Pack, iPhone 13 Always-On Display?

Saturday July 24, 2021 6:00 am PDT by
Apple's new MagSafe Battery Pack is now available, and we went hands-on this week for some early impressions of the new accessory to get more battery life out of Apple's iPhone 12 lineup. Subscribe to the MacRumors YouTube channel for more videos. This week also saw a number of rumors about the upcoming redesigned MacBook Pro models, the iPhone 13 lineup, the next-generation iPad mini, a new...