Swift 4 is a new programming language developed by Apple Inc for iOS and OS X development. Swift 4 adopts the best of C and Objective-C, without the constraints of C compatibility. Swift 4 uses the same runtime as the existing Obj-C system on Mac OS and iOS, which enables Swift 4 programs to run on many existing iOS 6 and OS X 10.8 platforms.
Swift brings a lot of advantages over Objective-C. Perhaps the most important to existing iOS/OS X developers is the new features it brings like better type safety, better memory management, multiple return values, and a bunch of functional paradigms. All these features mean that seasoned developers will not have to spend as long coding. Apple also boasts increased performance over Objective-C (and they even compared it to Python since it can act like a scripting language). Another great feature is its interoperability with existing Objective-C code. Looking through the Swift reference, it seems pretty trivial to mix and match old Objective-C code with Swift code, which will make the process of converting apps an easier, more iterative one.
Swift is also great for people interesting in developing for iOS/OS X. Objective-C is a notoriously difficult language since its syntax is unlike that of any other major programming language. Swift's syntax is much more concise and friendly, taking some influence from languages like Python, Ruby, and Rust.
It's hard to think of any huge downsides to using Swift rather than Objective-C. The only thing I can think of is that some developers might not be so keen on converting their apps since they've invested so much time into learning and using Objective-C and their codebases are likely big.
The transparency in its code leads to a faster development time. In addition to that, you also get a product that is “future-proof” and can be added with new features. This leads to easier scalability. Plus, for your long-term investments, you need to consider that Apple is more likely to support Swift rather than Objective-C.
Safety and Improved Performance
As its name suggests, Swift is created to be – swift. It puts emphasis on speed and performance which initially was 40% more than Objective -C, on both accounts. With multiple yardsticks crossed and tests conducted by developers, this is more than evident.
Another advantage of Swift programming language is safety. Owing to its robustness and statically-typed characteristic, Swift enables developers to determine bugs before compilation and thus fix them on the fly. Furthermore, Swift has smart nil-pointer safety measures that avert errors in compiling caused by null references.
Swift supports not only iPads and iPhones, but all Apple devices- like Apple watch, Apple TV and Mac.