Apple Xcode for Lion/Mountain Lion

Xcode 4 has been streamlined to help you write better apps. It has unified user interface design, coding, testing, and debugging all within a single window. The Xcode IDE analyzes the details of your project to identify mistakes in both syntax and logic, it can even help fix your code for you. 

Xcode runs on OS X Mountain Lion and OS X Lion, and includes the Xcode IDE, Instruments, iOS Simulator, the latest Mac OS X and iOS SDKs, and hundreds of powerful features:

Innovative tools to help you create great apps
• Interface Builder is fully integrated as a design canvas within the Xcode IDE
• The Assistant shows files related to what you're editing, such as the header, superclass, or controller
• The Version editor shows a live source code comparison through Git or Subversion history
• Live Issues display errors as you type, and Fix-it can correct the mistakes for you
• Apple LLVM compiler is embedded within the IDE with support for Objective-C, C, and C++
• The new LLDB debugging engine is faster and more memory-efficient than GDB
• Instruments adds System Trace and new iOS instruments including OpenGL ES

Streamlined interface that is faster and easier to use
• Design your interface side by side with the backing source code
• Create connections from your GUI design directly to the related source code
• Use tabs to organize your workspace, or double-click to open files in a new window
• Schemes let you customize exactly how your app will build, run, profile, and deploy
• Debugging and console views slide in without disturbing your place in the editor

Professional editor keeps you focused on your code
• Click the Jump Bar at the top of the editor to instantly go to another file
• View message bubbles to see errors, warnings, and other issues right beside the code
• Use the ribbon on the left of the editor to fold your code, or highlight scope

Embedded Apple LLVM technology finds and fixes bugs for you
• Analyzer travels countless code paths looking for logical errors before they become bugs
• Live Issues underlines coding mistakes as you type with no need to build first
• Fix-it can confidently correct mistakes for you with just a keystroke
• Code completion for Objective-C, C, and C++ is incredibly fast and accurate

Instruments for visual performance analysis
• Compare CPU, disk, memory, and OpenGL performance as graphical tracks over time
• Identify performance bottlenecks then dive deep into the code to uncover the cause
• Monitor your app directly, or sample the entire system, with very little overhead

To test or deploy applications on an iOS device you must be a member of Apple's iOS Developer Program.  To submit your Mac or iOS apps to the App Store you must be a member of the Mac or iOS Developer Program.  Some features may require Internet access.

Whats New in Version 4.5.1
• Fixes an issue where the debug console failed to display some text.
• Improves stability when targeting the iOS Simulator.
• Additional bug fixes and stability improvements.

Included in Xcode 4.5:
• SDKs for OS X 10.8 Mountain Lion and iOS 6.
• Auto Layout now supported on both OS X and iOS.
• New localization workflow can share a single base .xib or .storyboard file for multiple locales.
• OpenGL debugger for iOS analyzes performance and suggests improvements.
• Debugger watchpoints can be set when running on a connected iOS device.
• Objective-C @synthesize command is generated by default when using properties.
• Objective-C adds literal syntax for numbers, arrays, dictionaries, and expressions.
• Xcode 4.5 runs on both OS X Lion and OS X Mountain Lion.
• Enhanced for the MacBook Pro with Retina display.

What's New in Version 4.5.2
• Support for iPad mini and iPad with Retina display (4th generation).
• Additional bug fixes and stability improvements.

Included in Xcode 4.5:
• SDKs for OS X 10.8 Mountain Lion and iOS 6.
• Auto Layout now supported on both OS X and iOS.
• New localization workflow can share a single base .xib or .storyboard file for multiple locales.
• OpenGL debugger for iOS analyzes performance and suggests improvements.
• Debugger watchpoints can be set when running on a connected iOS device.
• Objective-C @synthesize command is generated by default when using properties.
• Objective-C adds literal syntax for numbers, arrays, dictionaries, and expressions.
• Xcode 4.5 runs on both OS X Lion and OS X Mountain Lion.
• Enhanced for the MacBook Pro with Retina display.

What's New in Version 4.6:

Includes SDKs for OS X 10.8 Mountain Lion and iOS 6.1.
Code completion heuristics are more accurate, and use an optimized default data set.
• New compiler warnings help identify potential bugs when using ARC and weak references.
• C++11 support for ‘user defined literals’ and ‘unrestricted unions’ features.
• Debugger can inspect elements within NSArray or NSDictionary objects.
• Analyze now performs deeper cross-function static analysis of Objective-C and C++ code.
• The number of indexing passes is reduced due to improved dependency checking.
• Additional bug fixes and stability improvements.

What's New in Version 4.6.1

• Updates the OS X SDK to support OS X Mountain Lion version 10.8.3.
• Fixes an issue where ARC-enabled apps would not launch on OS X 10.6 Snow Leopard.
• Fixes a performance regression in the Analyze operation.

Included in Xcode 4.6:

• Includes SDKs for OS X 10.8 Mountain Lion and iOS 6.1.
• Code completion heuristics are more accurate, and use an optimized default data set.
• New compiler warnings help identify potential bugs when using ARC and weak references.
• C++11 support for ‘user defined literals’ and ‘unrestricted unions’ features.
• Debugger can inspect elements within NSArray or NSDictionary objects.
• Analyze now performs deeper cross-function static analysis of Objective-C and C++ code.
• The number of indexing passes is reduced due to improved dependency checking.
• Additional bug fixes and stability improvements.

Version 4.6.2:
• Improves LLDB performance for debugging Objective-C code.
• Fixes an issue where the crash log database could grow very large.
• Additional bug fixes and stability improvements.
• Xcode in the Mac App Store has been repackaged, and is now distributed as a stand-alone application. This replaces the Install Xcode package, and adds support for delta updates. Xcode includes a new "Downloads" preference pane to install optional components such as command line tools, and previous iOS Simulators.