Tim Stevens su CNET:
Scripting languages, like Python, tend to be easy to write and easy to test, but they aren’t particularly powerful and generally don’t perform well. Not ideal when you’re writing, say, a game that needs access to the full power of your device. Traditional programming languages, like Objective-C, give better access to the power of the device and enable the creation of more comprehensive apps, but are difficult to learn and tedious to compile and test.
Swift promises to have all the good with none of the bad. Apple promises that, at least in a few key benchmarks, it is considerably faster to execute than Python and faster even than Objective-C. But, despite that, the language supports what’s called “playgrounds” within the Xcode developer environment, visualizing Swift code in real-time, like a scripting language.