Advanced Swift: Course Overview

Welcome to our Advanced Swift course! This course is designed for beginning iOS developers who have a basic understanding of Swift and are ready to take their skills to the next level. In this course, we will cover a range of advanced topics that will help you become a more proficient and effective Swift programmer.

Extensions

Extensions allow you to add new functionality to existing classes, structures, enumerations, or protocols. This is particularly useful when you do not have access to the original source code. Extensions can add new methods, properties, and subscripts.

extension Int {
    var isEven: Bool {
        return self % 2 == 0
    }
}

Protocols

Protocols define a blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality. They can be adopted by classes, structures, and enumerations.

protocol Greetable {
    func greet() -> String
}

class Person: Greetable {
    func greet() -> String {
        return "Hello!"
    }
}

Static Functions and Objective-C Functions

Static functions are functions that belong to a type itself rather than an instance of a type. They are called on the type, not on an instance of the type. Objective-C functions are functions that can be exposed to Objective-C runtime, allowing Swift code to interact with Objective-C code.

class Math {
    static func add(a: Int, b: Int) -> Int {
        return a + b
    }
}

@objc class ObjectiveCClass: NSObject {
    @objc func doSomething() {
        print("Doing something")
    }
}

Actors

Actors are a new reference type in Swift that protect access to their mutable state. They are used to handle concurrency by ensuring that only one task can access the actor’s state at a time.

actor BankAccount {
    private var balance: Int = 0
    
    func deposit(amount: Int) {
        balance += amount
    }
    
    func getBalance() -> Int {
        return balance
    }
}

Initializers and De-initializers

Initializers are special methods that prepare an instance of a class, structure, or enumeration for use. De-initializers are called immediately before a class instance is deallocated to perform cleanup.

class Vehicle {
    var make: String
    
    init(make: String) {
        self.make = make
    }
    
    deinit {
        print("\(make) is being deinitialized")
    }
}

Optional Chaining

Optional chaining is a process for querying and calling properties, methods, and subscripts on an optional that might currently be nil. If the optional contains a value, the call succeeds; if the optional is nil, the call returns nil.

class Person {
    var residence: Residence?
}

class Residence {
    var numberOfRooms = 1
}

let john = Person()
if let roomCount = john.residence?.numberOfRooms {
    print("John's residence has \(roomCount) room(s).")
} else {
    print("Unable to retrieve the number of rooms.")
}

Advanced Operators

Swift includes several advanced operators that perform bitwise and bit shifting operations, among others. These operators are useful for low-level programming tasks.

let initialBits: UInt8 = 0b00001111
let invertedBits = ~initialBits  // equals 0b11110000

ARQ in Swift

ARQ (Automatic Reference Counting) is a memory management feature of Swift that automatically keeps track of and manages your application's memory usage.

class ExampleClass {
    var someProperty: String
    
    init(someProperty: String) {
        self.someProperty = someProperty
    }
    
    deinit {
        print("\(someProperty) is being deinitialized")
    }
}

Opaque Types

Opaque types enable a function to return a value of some type that conforms to a protocol, without specifying the exact type. This helps in maintaining abstraction and hiding implementation details.

func makeOpaqueContainer() -> some Container {
    return [1, 2, 3]
}

Subscripts

Subscripts are shortcuts for accessing the member elements of a collection, list, or sequence. You can define subscripts in classes, structures, and enumerations.

struct TimesTable {
    let multiplier: Int
    
    subscript(index: Int) -> Int {
        return multiplier * index
    }
}

let threeTimesTable = TimesTable(multiplier: 3)
print("six times three is \(threeTimesTable[6])")

Typecasting

Typecasting in Swift is implemented with the "as" keyword and is used to check the type of a value or to cast a value to a different type. This is particularly useful when working with heterogeneous collections.

let someObjects: [Any] = [0, "Hello", 42.0]
for object in someObjects {
    if let string = object as? String {
        print("Found a string: \(string)")
    }
}

Concurrency

Concurrency in Swift allows multiple pieces of code to run simultaneously, making your app more efficient and responsive. Swift's concurrency model includes async/await, tasks, and more.

func fetchImage() async throws -> UIImage {
    let url = URL(string: "https://example.com/image.jpg")!
    let (data, _) = try await URLSession.shared.data(from: url)
    return UIImage(data: data)!
}