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iOS 6 Programming Pushing the Limits: Advanced Application Development for Apple iPhone, iPad and iPod Touch by Mugunth Kumar, Rob Napier

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Chapter 2: Getting Comfortable with Xcode 4 and the LLVM Compiler

Apple officially announced Xcode 4 at WWDC 2010 (June 2010), and the beta version was available to attendees. It was in beta for quite a while (around nine months), and a Gold Master was made available through the iOS/Mac developer center in February 2011. Weeks later, in March, Xcode 4 was officially released, and developers who subscribe to the iOS or Mac developer programs were able to get it for free. Others were able to buy it from the Mac App Store.

Xcode 4 is a completely rewritten IDE (integrated development environment) replacing Xcode 3. The major features include, but are not limited to, single window editing, navigators, integrated Interface Builder, an integrated Git version control system, and schemes (a new way to configure and share build settings in your product). You learn in detail about every major feature in this chapter.

Xcode 4 features are not just skin deep—they come with some huge compiler-level changes as well. The LLVM compiler is the new brain behind Xcode. Apple made LLVM-GCC the default compiler in the original version of Xcode. Beginning with Xcode 4.0 and in the version that is released with iOS 5 (Xcode 4.2), LLVM 3.0 was the default compiler; it uses Clang as its front end. Using Clang as the front end over GCC has several advantages, and several new features of Xcode 4 were added because of this change. With Xcode 4.5 (released with iOS 6), Apple made LLVM 4 the default compiler. ...

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