Xcode 4 for building MacOSX (Cocoa-Based) and iOS applications has a few new features from its predecessors making it easier and more productive to work with.
New User Interface – The first thing that will strike you will be the new redesigned user interface, featuring a single-window integrated development interface. This new single window feature lets you work in one single window rather than cluttering your working area with many windows to perform the development tasks you do each day.
Interface Building – now fully integrated within Xcode development IDE allowing you to work on several projects all in the one window.
Jump Bar – The Jump Bar feature allows you to click any location in the path so you can directly jump from file to file for quick access.
Support – C++11 Features Support
Code Assistant – in a 2nd window it displays the file you are working on and can auto find and open the corresponding header files
Otool – has been improved to support disassembly of Intel AVX instructions, decode all instructions and skip over data entries in text segments.
Improvements to LLDB debugger – reads metadata from the Objective-C runtime. Inspect elements of NSArray and NSdictionary in the Xcode debugger. Many bug fixes and shortcuts have been made with stability and speed improvements, using less memory than the GDB debugging engine.
Fix-it – Fixes code errors for you, checks the syntax of your code and symbol names as you type, highlighting any errors. Also Identifies mistakes in both syntax and logical errors.
LLVM – Low Level Virtual Machine debugger which runs 3 times faster and 2.5 times more efficient. Supporting C, Objective-C and C++
Version Editor – now works with GIT (Free Open Source) version control software or subversion. Showing files SCM history and can compare any 2 file versions.
Customize – as many debugging and build tools as you need.
Download Xcode free of charge if you are a Mac OS X Lion or OS X Mountain Lion user via the Mac App Store.