In Xcode 6, new features include
Support for Swift : Xcode 6 explicitly supports the Swift code, it is very simple and easy to make a brand new app using 100% swift code to existing frameworks.
Playgrounds : It enables the interactive experience of a scripting language, like you can show variables in a graph, watch an animated SpriteKit Scene or inspect each step when drawing a view. Once you are done with code in the playground, you can move it into your project
Command Line : You can use Swift syntax to interact and evaluate with your running app or write new code in a script like environment
Performance Testing : The XCTest framework is extended to support performance test, and is completely synchronized with Xcode and Xcode Server. It also raises alerts for regression when test results change
View Debugging : Xcode allows easy debugging and includes new debugging tools like debug gauges to monitor I/O usage and enhance iCloud gauge
