What’s new in Swift 5.3?

Swift 5.3 goes to be an thrilling new launch. This publish is a showcase of the newest Swift programming language options.


The Swift 5.3 launch course of began in late March, there are many new options which are already carried out on the 5.3 department. In case you are curious what are these you’ll be able to strive it out by putting in the newest snapshot utilizing swiftenv for instance, you’ll be able to seize them from swift.org.

Package deal Supervisor updates

Swift Package deal instruments model 5.3 will characteristic some actually nice additions.


With the implementation of SE-0271 the Swift Package deal Supervisor can lastly bundle useful resource recordsdata alongside code. I imagine that this was fairly a well-liked request, since there are some libraries that embed asset recordsdata, they weren’t in a position so as to add SPM assist, till now.

Localized sources

SE-0278 extends the useful resource assist, with this implementation you’ll be able to declare localized sources on your Swift packages. The outline explains nicely the proposed construction, it’s best to have a look in case you are keen on delivery localized recordsdata along with your package deal.

Binary dependencies

The opposite great point is that SPM will lastly have the ability to use binary dependencies. SE-0272 provides this functionality so individuals who wish to ship closed supply code can now make the most of this characteristic. It will make it potential to have a binaryTarget dependency at a given path or location and you need to use the binary as a product in a library or executable.

Conditional Goal Dependencies

SE-0273 offers us a pleasant little addition so we will use dependencies based mostly on given platforms. Because of this you need to use a product for a goal if you construct for a selected platform.

These options are nice additions to the SPM, hopefully Xcode will profit from this stuff as nicely, and we’ll see some nice new enhancements within the upcoming model of the IDE too.

Language options

There are various new attention-grabbing proposals that bought into the 5.3 model.

A number of Trailing Closures

SE-0279 is without doubt one of the most debated new proposal. After I first noticed it I used to be undecided in regards to the want of it, why would somebody put a lot effort to get rid of a couple of brackets? 🤔

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {

        UIView.animate(withDuration: 0.3, animations: {
          self.view.alpha = 0
        }, completion: { _ in
        UIView.animate(withDuration: 0.3, animations: {
          self.view.alpha = 0
        }) { _ in

        UIView.animate(withDuration: 0.3) {
          self.view.alpha = 0
        UIView.animate(withDuration: 0.3) {
            self.view.alpha = 0
        } completion: { _ in

As you’ll be able to see that is principally a syntactic sugar, however I satisfied myself that it’s good to have.

Synthesized Comparable conformance for enum sorts

Enum sorts do not need to explicitly implement the Comparable protocol due to SE-0266.

enum Membership: Comparable {
    case premium(Int)
    case most well-liked
    case common
([.preferred, .premium(1), .general, .premium(0)] as [Membership]).sorted()

The Comparable protocol is robotically synthesized, identical to the Equatable and Hashable conformances for eligible sorts. In fact you’ll be able to present your personal implementation if wanted.

Enum circumstances as protocol witnesses

Swift enums are loopy highly effective constructing blocks and now they simply bought higher. 💪

protocol DecodingError {
  static var fileCorrupted: Self { get }
  static func keyNotFound(_ key: String) -> Self

enum JSONDecodingError: DecodingError {
  case fileCorrupted
  case keyNotFound(_ key: String)

The primary objective of SE-0280 to carry an present restriction, this fashion enum circumstances could be protocol witnesses if they supply the identical case names and arguments because the protocol requires.

Kind-Primarily based Program Entry Factors

SE-0281 offers us a brand new @essential attribute that you need to use to outline entry factors on your apps. This can be a welcome addition, you do not have to jot down the MyApp.essential() technique anymore, however merely mark the MyApp object with the principle attribute as a substitute.

class AppDelegate: UIResponder, UIApplicationDelegate {

    static func essential() {
        print("App will launch & exit immediately.")

The UIApplicationMain and NSApplicationMain attributes shall be deprecated in favor of @essential, I might wager that is coming with the following main launch…

Multi-Sample Catch Clauses

SE-0276 is one other syntactic sugar, it is actually useful to catch a number of circumstances without delay.

do {
    strive performTask()
catch TaskError.someRecoverableError {
    get well()
catch TaskError.someFailure(let msg), TaskError.anotherFailure(let msg) {

This eliminates the necessity of utilizing a change case within the catch block. ✅


Nothing a lot to say right here, SE-0277 provides Float16 to the usual library.

let f16: Float16 = 3.14

Generic math features are additionally coming quickly…

Self adjustments

SE-0269 aka. Enhance availability of implicit self in @escaping closures when reference cycles are unlikely to happen is a pleasant addition for individuals who don’t love to jot down self. 🧐

execute {
    let foo = self.doFirstThing()
    performWork(with: self.bar)
    self.doSecondThing(with: foo)

execute { [self] in
    let foo = doFirstThing()
    performWork(with: bar)
    doSecondThing(with: foo)

It will permit us to jot down self within the seize checklist solely and omit it afterward contained in the block.

Refine didSet Semantics

SE-0268 is an below the hood enchancment to make didSet habits higher & extra dependable. 😇

class Foo {
    var bar = 0 {
        didSet { print("didSet known as") }

    var baz = 0 {
        didSet { print(oldValue) }

let foo = Foo()

foo.bar = 1

foo.baz = 2

In a nutshell beforehand the getter of a property was all the time known as, however any more it will be solely invoked if we use to the oldValue parameter in our didSet block.

Add Assortment Operations on Noncontiguous Components

SE-0270 provides a RangeSet sort for representing a number of, noncontiguous ranges, in addition to quite a lot of assortment operations for creating and dealing with vary units.

var numbers = Array(1...15)

let indicesOfEvens = numbers.subranges(the place: { $0.isMultiple(of: 2) })

let sumOfEvens = numbers[indicesOfEvens].scale back(0, +)

let rangeOfEvens = numbers.moveSubranges(indicesOfEvens, to: numbers.startIndex)

This proposal additionally extends the Assortment sort with some API strategies utilizing the RangeSet sort, it’s best to have a look in case you are working rather a lot with ranges. 🤓

The place clauses on contextually generic declarations

With SE-0267 you can implement features and put a the place constraint on them in case you are solely referencing generic parameters. Take into account the next snippet:

protocol P {
    func foo()

extension P {
    func foo() the place Self: Equatable {

This would possibly not compile on older variations, however it’ll work like magic after Swift 5.3.

Add a String Initializer with Entry to Uninitialized Storage

SE-0263 provides a brand new String initializer that lets you work with an uninitialized buffer.

let myCocoaString = NSString("The fast brown fox jumps over the lazy canine") as CFString
var myString = String(unsafeUninitializedCapacity: CFStringGetMaximumSizeForEncoding(myCocoaString, ...)) { buffer in
    var initializedCount = 0
    return initializedCount

By utilizing this new init technique you do not have to fiddle with unsafe pointers anymore.

Future evolution of Swift

At the moment there are 6 extra accepted proposals on the Swift evolution dasboard and one is below assessment. Swift 5.3 goes to comprise some wonderful new options that had been lengthy awaited by the neighborhood. I am actually completely happy that the language is evolving in the proper path. 👍