I've read all there is to read on Apple's website, but being that I'm not a developer, I still don't concretely understand the real world benefit here.
Are there a few people from the developer community out there who can explain the change to us as if they're talking to a 5 year old?
I'd love to grasp the impact in a more concrete way.
Apple developing a new programming language that's "simpler, faster, easier" etc sounds great and sets off fireworks on the blogs.. but I'm trying to really gauge exactly what the jump is.
I'll explain what I see as the three biggest benefits as succinctly as I can.
The first thing is safety. The language has very strict rules about defining your
intent with code you write. When you go read your code days or years later, the language forced you to be very clear what you meant to do so it's a lot easier to use functions or reuse code without making mistakes and causing bugs. Also, since your intentions are so clear, the compiler can do additional sorts of checks that just aren't possible in some other languages. When you go to compile your project, the compiler will pop up errors that immediately point to where you have problems you might never otherwise be able to track down when they start popping up in a another languages's compiled, running program. There are other aspects of safety built into Swift, such as the way memory is handled (initializations, optionals, automatic reference counting...), but those are two of the easiest to understand for a 5 year old.
The second thing is expressiveness. The language allows you to express complex logical ideas in rather elegant ways. You can type less to get the same results, and what you type is a lot easier to read as a human being. Bear in mind, this also relates to safety, above. Because complexity is expressed in a short, human-readable way, it's far more easy to identify bugs, or avoid making them to begin with.
The third thing is optimization. The language seems designed from the ground up to produce highly optimized compiled applications. This is accomplished through a variety of ways, but the expressiveness and safety of the language feed into that goal. The better you can express your intentions to the compiler, the more optimizations the compiler can make on your code.
So that's basically why most people are excited about Swift. It
should save skilled developers time, and it should also guide less experienced developers into making fewer mistakes. Debugging should be easier for both. The compiled code may be a little faster running.
No developer with a huge amount of Objective-C code is going to rewrite all of it. They may or may not rewrite sections in Swift as they go in and debug or otherwise update existing code. Many developers may choose to start a new project entirely in Swift. The biggest thing to take from all of this is there are now two language options with "first class citizen" status for Apple development. More choices are always good. No one language is perfect for all projects, and developers now have a choice of another language to use that may or may not offer significant advantages. I think in the long run Swift will get most of the attention by developers and Apple itself, but it's still very new and it'll take some time to figure out just how advantageous it really is.
The downsides of course should be obvious. It takes time to learn a new language, and that time takes away from development time. Because the language is new there's very few resources and documentation is relatively scarce. The only people with any experience using the language are working for Apple, so companies can't just hire experienced Swift programmers like they can Objective-C programmers.
