- Quinton Belcastro
- quinton.belcastro@uoit.net
Swift was specifically developed for the Apple ecosystem and supports iOS, macOS, watchOS, tvOS, Linux and z/OS. Swift is a general-purpose, multi-paradigm, compiled programming language. Since it is multi-paradigm it means it supports many different many different programming paradigms. In the case of Swift it supports functional programming paradigms as well as object oriented paradigms and generic programming paradigms. This lends to Swifts incredible versatility.
- History: Swift's development did not begin until 2010. Chris Lattener was the lead developer on the project at the time and it wasn't until the project grew that other apple engeneers were brought on board. Chris has stated in the past that he took inspiration "from Objective-C, Rust, Haskell, Ruby, Python, C#, CLU, and far too many others to list" when developing the programming features of swift. It wasnt until 2014 at the Apple Worldwide Developers Conference that people were exposed to swifts capabilties and the first beta of Swift was released. The first official release of swift wasn't until later that year in September of 2014.
- Features: Swift has several unique features which seperate it from other languages:
- Scoping / Accesibility: In swift there are 5 different types you can apply to symbols to control access open, public, internal, fileprivate, and private. However unlike most langauges access controls ignore inheritance. Fileprivate is a little unique and allows the symbol to only be accesed within the file.
- Simple Syntax: Many basic types have been added to the languages core. For instance strings are invisibly connected to the NSString library and can be concatenated simply using the + operator
- Protocols: as with clojure swift has support for some protocol oriented programming. Protocals allow for the extension of classes without ever having to have access to the original class. Protocols can be created in isolation and then be extended later for specific classes, this use of generic programming lends itself well to swift's flexability.
Here is a quick look at some of the various syntax available in Swift. For more details and examples you should look at the basic_syntax.swift file on this repo.
Variable Declaration
///Declare a variable
var name = "Quinton"
///Declare a constant
let five = 5
///Declare accessability of variable
private var privName = "Mirriam"
///or fileprivate
fileprivate var fileprivName = "Beth"Conditionals
var favFruit = "apple"
if !(favFruit=="apple") {
print("Your fav fruit is crummy!")
}Iteration
For form
for i in 1...10 {
print(i)
}While form
var i = 1
while i <= 10 {
print(i)
i = i + 1
}Repeat form (do-while in most languages)
var i = 1
repeat {
print(i)
i = i + 1
} while i < 10Functions
func isEven(number: Int) -> Bool {
if number % 2 == 0 {
return true
} else {
return false
}
}Swift uses its own unique compiler based on the LLVM compiler framework. The swift compiler operates very similarly to others but with a few unique expections.
- Clang importer
- Swift Intermediate Language Generation
- Swift Intermediate Language Optimizations
If you install the swift compiler from their website and the other tools they have available you can enter a REPL in your terminal to practice using the language.
Other Tools:
- There are many different package / dependency managers for Swift one that I found interesting was Cocoa
- There are also online interpreters that can run Swift code. For begginers these are great tools because you dont have to mess around with the setup and still get to use the language
offered by the standard library_. As with most modern programming langauges the standard library contains many useful functions and data types to help in everyday programming. The Swift Standard Library is unique in that it includes various protocols that can be used to describe common abstractions. Here are a few examples of what comes in the Swift Standard Library:
- Fundatmental Data Types: Int, Double, String etc
- Commonly Used Data Structures: Arrays, Sets and Dictionaries
- Functions: max(), min(), print(), readline(), swap(), type()
- Protocols: Collection and Equatable
Open Source Library: There are many useful open source libraries built for Swift using Swift. One that I found interesting was this JSON parser that helps to simplify that quite complex task of dealing with JSON in swift. By default parsing JSON can be tricky because Swift is very strict about types, however with this parser those difficulties go away which leads to fast and easy development. Below I have an example of just how much easier it can be (Example from libraries GitHub).
if let statusesArray = try? JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [[String: Any]],
let user = statusesArray[0]["user"] as? [String: Any],
let username = user["name"] as? String {
// Finally we got the username
}let json = JSON(data: dataFromNetworking)
if let userName = json[0]["user"]["name"].string {
//Now you got your value
}Other Open Source Projects: There are thousands of amazing open source projects made using Swift however one of the biggest and most recognizable is of course Firefox. The iOS version of the popular browser Mozzila Firefox is written and Swift and can be found here.
1. The style of programming supported by the language: functional vs procedural programming
Swift is a multi-paradigm programming language. This means that it is not distinctly functional or procedural. However with this in mind it certainly leans to the object-oriented procedural side of things. It has a lot of functional programming features that would allow one to program that way Swift immutable data structures like you would see in other functional programming lanuages using the let keyword. Swift has first class functions, functions act like data the same way values do. Lastly Swift has good function chaining syntax which allows one to quickly chain together many functions.
2. The ability to perform meta-programming such as macros
Swift doesn't directly support macros like objective c however the extensions and protocol framwork allow for "similar" functionality. The reality is a lot of boiler plate code has to be written and rewritten throughout ones program and any modifications made to the original protocols will need to be tracked through the entire program. Some people have worked on open-source projects to fix this issue. I found one useful Sourcery which helps to avoid a lot of this repetetive work.
3. Symbol resolution and its support for closure
Swift suports similarly to block in C and Objective-C. In Swift if you want to create a closure you have to surround your potential function block with {} and assign the closure to some variable. Any function and scope can be converted into a unique closure. When converting a function to a closure you must remove the function declaration and use the in keyword as a part of the closure declaration. If this function has no return value and no input variables we do not need to use the in keyword. See the code example for a better idea of how this works.
4. Scoping rules supported by the language: lexical vs dynamic scoping
Swift is for the most part dymic scoping. With the use of closures and the let keyword it is possible to implment lexical scoped scoping.
5. Functional programming constructs either as part of the language or supported by the standard library of the runtime.
There are several of functional programming contructs built into Swift. Firstly like most functional programming languages you can use closures, extensions and the let keyword to create what is basically lexical scoping. There is also the idea of function chaining which is a very important concept in Swift which allows you to combine and "chain" together several functions at once. Lastly through protocols and extensions you can perform operations similarly to what you might need whole classes and interfaces to do.
6. Its type system: static vs dynamic types
Swift is statically typed with no exceptions. Even extensions which are as close as one can get to a dynamic class have to be writen before compile time. However if you use Coaco than you gain access to the objective-c runtime enviroment and can therefor use its dynamic classes.
7. Strengths and weaknesses of the language
Swifts biggest strength come from Apple's continued support of the language. It is clear that Apple wants Swift to become a significant part of the programming market and is working hard on developing it. The flexability that swift provides is also a major benefit being able to program in an object oriented setting and quickly switch to a functional style if needed can be amazing for efficiency. The biggest weakness Swift suffers from is the restriction of compatibility. Huge swaths of the programming market, windows machines and android devices are simply not accessable to Swift developers.