Nearly two years after the SDK was launched, Apple realized the limitations of Objective-C and started working on a new language for iOS and OS X developers around 2010, namely, Swift.

Objective-C was already outdated, being 30 years old in the industry. A lot of developers suffered through learning the arcane syntax and other limitations of the language.

Finally in June 2014, Swift was first introduced by Apple as a general purpose and modern programming language. Since then, versions 1, 2, 3 and 4 have been released in addition to other changes like being open sourced. (Note: See a Version History below.)

Swift is a fantastic way to write software, whether it’s for phones, desktops, or, servers. It’s a safe, fast, and interactive programming language that draws inspiration from the best in modern language thinking and combines it with the wisdom of Apple’s engineering culture and diverse valuable contributions from its open-source community. The compiler is optimised for performance and the language is optimised for development, excelling in both department without compromising on either.

Swift also does away with large classes of common programming errors by adopting modern programming patterns, such as:

Swift code is compiled and optimized to get the most out of modern hardware. The syntax and standard library have been designed with the notion that the obvious way to write your code should also perform the best. Its combination of safety and speed make Swift an excellent choice for everything – from “Hello, world!” to an entire operating system.

Swift combines powerful type inference and pattern matching with a modern, lightweight syntax, allowing complex ideas to be expressed in a clear and concise manner. As a result, code is easier to write, read and maintain.

Moreover, Swift is friendly to new programmers. It’s an expressive and industrial-quality scripting programming language. Writing Swift code lets you experiment with code and see the results immediately, without the overhead of building and running an app.

Implications for Developers

As mentioned earlier, Swift is an open source language. It allows developers to prototype, write and maintain apps for Apple platforms in a faster and more accurate manner. Thus, it supports propagation of businesses and enterprises over Apple’s platforms.

Swift being open sourced means that the language will be expanded over to other platforms as well. In fact, it has already been ported to Linux. This, eventually, expands the usability of Swift over web apps based on low-cost, low-maintenance Linux servers as well. In addition, there are frameworks built for Swift so that Linux-based server apps can be built inside of Xcode, allowing businesses to utilize existing Swift developers to build the APIs and services that iOS and OS X apps often consume.

Versions of Swift 

Timeline –

Highlights of Swift 2.0 –

Highlights of Swift 3.0 – 

Highlights of Swift 4.0 –

Using Swift 

To use Swift, you need to download and install Xcode 6. Once installed, open it and select File from the Menu > New > Select Source on the left under either iOS or OS X > Playground. Give your playground a name and get started.

Alternatively, you can use the Read Evaluate Print Loop (REPL) from the terminal, as instructed below:

While the minimum basics of using Swift are mentioned above, Swift 4 is packaged along with Xcode 9 and has a Swift Migrator tool that helps you migrate your project to Swift 4.

Also, Xcode 9 supports Swift 4 and Swift 3.2 equally and compile them together, just like the Swift 4 compiler can. That means you decide when and if you’d like to migrate on a per-target basis when it makes sense for your project. While migrating to Swift 4 is definitely encouraged, it’s not an all-or-nothing process, as Swift 3.2 and Swift 4 targets can coexist and link together.

Fundamentals of Swift

1.Value Types

Like C, Swift uses variable to store and refer to values by an identifying name. It also makes extensive use of variables, also known as constants, that is, their values can’t be changed. Constants are used throughout Swift to make code safer and clearer in intent when you work with values that don’t need to change. A few familiar value types include Int for integers, Double and Float for floating-point values, Bool for Boolean values and String for textual data. In addition to familiar types, Swift introduces advanced types, such as tuples and optionals. Tuples enable you to create and pass around groupings of values. You can use a tuple to return multiple values from a function as a single compound value. Optional types handle the absence of a value. Optionals say either “there is a value, and it equals x” or “there isn’t a value at all”. Constants and variables associate a name with a value of a particular type. The value of a constant can’t be changed once it has been set, whereas a variable can be set to a different value in the future. Both constants and variables must be declared before they’re used. You declare constants with the let keyword and variables with the var keyword. For instance, to track the login attempts made by a user, you can use – 

let maximumNumberOfLoginAttempts = 10 
var currentLoginAttempt = 0

2.Strings and Characters 

A string is a series of characters, such as “hello, world” or “albatross”. Swift strings are represented by the String type. The contents of a String can be accessed in various ways, including as a collection of Character values.Swift’s String and Character types provide a fast, Unicode-compliant way to work with text in your code. The syntax for string creation and manipulation is lightweight and readable, with a string literal syntax that is similar to C. String concatenation is as simple as combining two strings with the + operator, and string mutability is managed by choosing between a constant or a variable, just like any other value in Swift. You can also use strings to insert constants, variables, literals, and expressions into longer strings, in a process known as string interpolation. This makes it easy to create custom string values for display, storage, and printing.Despite this simplicity of syntax, Swift’s String type is a fast, modern string implementation. Every string is composed of encoding-independent Unicode characters, and provides support for accessing those characters in various Unicode representatio

3.Collection Types 

Swift provides three primary collection types, known as arrays, sets, and dictionaries, for storing collections of values. Arrays are ordered collections of values. Sets are unordered collections of unique values. Dictionaries are unordered collections of key-value associations.Collection types in Swift are well-defined about the types of value and keys they can store, thus eliminating the chances of error in inserting a value of wrong type in a collection by mistake. In other words, you can be sure about the value types you will retrieve from a particular collection.The mutability of collection depends on the type of value type it has been assigned to – a collection type assigned to a variable will be mutable, whereas a collection type assigned to a constant will be immutable. 

 3.1  Array

An empty array can be created using initializer syntax –

var someInts = [Int]() 
print(“someInts is of type [Int] with \(someInts.count) items.”) 
// Prints “someInts is of type [Int] with 0 items.”

Similarly, you can also create an array of a certain size with all of its values set to the same default as shown below –

var threeDoubles = Array (repeating: 0.0, count: 3) 
// threeDoubles is of type [Double], and equals [0.0, 0.0. 0.0]

To access or modify an array, you can use its methods or properties, or use subscript syntax.

First of all, find out the number of items in an array through its count property –

Print(“The shopping list contains \(shoppingList.count) items.”) 
// Prints “The shopping list contains 2 items.”

You can add a new item to the end of an array by append(_:) method. Alternatively, you can append an array of one or more compatible items with the addition assignment operator (+=). Moreover, you can retrieve a value from the array by using subscript syntax, passing the index of the value you want to retrieve within square brackets immediately after the name of the array. You can also use subscript syntax to change an existing value at a given index, or to change a range of values at once, even if the replacement set of values has a different length than the range you are replacing. To insert an item into the array at a specified index, use the array’s insert(_:at:)method.

Similarly, you remove an item from the array with the remove(at:) method. However, to remove the final item from an array, use the removeLast() method rather than the remove(at:) method to avoid the need to query the array’s count property. 

3.2  Sets

A set stores distinct values of the same type in a collection with no defined ordering. You can use a set instead of an array when the order of items is not important, or when you need to ensure that no item is being repeated.A type must be hashable in order to be stored in a set—that is, the type must provide a way to compute a hash value for itself. All of Swift’s basic types (such as String, Int, Double, and Bool) are hashable by default, and can be used as set value types or dictionary key types.

The type of a Swift set is written as Set, where Element is the type that the set is allowed to store. Unlike arrays, sets do not have an equivalent shorthand form. You can create an empty set of a certain type using initializer syntax –

var letters = Set<Character>() 
print(“letters is of type Set<Character> with \(letters.count) itmes.”) 
// Prints “letters is of type Set<Characher> with 0 items.”

You access and modify a set through its methods and properties. You can add a new item into a set by calling insert(_:) method. You can remove an item from a set by calling the remove(_:)method. Alternatively, all items in a set can be removed with its removeAll() method. To check whether a set contains a particular item, use the contains(_:) method.

3.3 Dictionaries

A dictionary stores associations between keys of the same type and values of the same type in a collection with no defined ordering. Each value is associated with a unique key, which acts as an identifier for that value within the dictionary. You use a dictionary when you need to look up values based on their identifier, much like using a real-world dictionary is to look up the definition for a particular word.The type of a Swift dictionary is written in full as Dictionary<Key, Value>, where Key is the type of value that can be used as a dictionary key, and Value is the type of value that the dictionary stores for those keys. You can also write the type of a dictionary in shorthand form as [Key: Value].

Similar to a Set, the value types in a Dictionary need to be hashable, and need not follow a particular order.

Similar to an Array, you can create an empty Dictionary of a certain type by using initializer syntax –

var namesOfIntegers = [Int: String]() 
// namesOfIntegers is an empty [Int: String] dictionary

You can also initialize a dictionary with a dictionary literal, which is a shorthand way to write one or more key-value pairs as a Dictionary collection. A key-value pair is a combination of a key and a value. In a dictionary literal, the key and value in each key-value pair are separated by a colon. The key-value pairs are written as a list, separated by commas, surrounded by a pair of square brackets – [key 1: value 1, key 2: value 2, key 3: value 3]

You access and modify a dictionary through its methods and properties, or by using subscript syntax.

4.Control Flow 

Swift provides a variety of control flow statements, such as while loops to perform a task multiple times; if, guard, and switch statements to execute different branches of code based on certain conditions; and statements like break and continue to transfer the flow of execution to another point in your code. Swift also provides a for-in loop that makes it easy to iterate over arrays, dictionaries, ranges, strings, and other sequences.Swift’s switch statement can match many different patterns, including interval matches, tuples, and casts to a specific type. Matched values in a switch case can be bound to temporary constants or variables for use within the case’s body, and complex matching conditions can be expressed with a where clause for each case.

4.1 For-in Loops
You use the for-in loop to iterate over a sequence, such as items in an array, ranges of numbers, or characters in a string. For example, the for-in loop is used here to iterate over the items in an array –

let names = [“Anna”, “Alex”, “Brian”, “Jack”]	
for name in names {
print(“Hello, \(name)!’)
{
// Hello, Anna!
	
// Hello, Alex!
	
// Hello, Brian!
	
// Hello, Jack!

You can also iterate over a dictionary to access its key-value pairs. The contents of a Dictionary are inherently unordered, and iterating over them does not guarantee the order in which they will be retrieved. In other words, the order you insert items into a Dictionary doesn’t define the order they are iterated.

5.Generics

Generic code enables programmers to write flexible, reusable functions and types that can work with any type, subject to requirements that you define. Using a generic code in Swift, you can write code that avoids duplication and expresses its intent in a clear, abstracted manner.Generics are one of the most powerful features of Swift, and much of the Swift standard library is built with generic code. For example, Swift’s Array and Dictionary types are both generic collections. You can create an array that holds Int values, or an array that holds String values, or indeed an array for any other type that can be created in Swift. Similarly, you can create a dictionary to store values of any specified type, and there are no limitations on what that type can be.

To make a generic function or type, you just have to write a name inside angle brackets –

func makeArray<Item>(repeating item: Item, numberOfTimes: Int) -> [Item] { 
var result = [Item]() 
for _ in 0..<numberOfTimes { 
result.append(item) 
} 
return result 
} 
makeArray(repeating: “knock”, numberOfTimes: 4)
 

Conclusion

The above guide illustrates many basic aspects of programming in Swift. However, there is a lot more Swift is capable of. To understand how Swift and Apple’s platforms can help you propagate your business to a wider audience, get in touch with us at hello@codetoart.com with our Swift experts.

(NOTE: Sample codes mentioned in the article and detailed guides can also be studied here.)

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