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 might be already carried out on the 5.3 department. In case you are curious what are these you’ll be able to attempt it out by putting in the newest snapshot utilizing swiftenv for instance, you’ll be able to seize them from swift.org.

Bundle Supervisor updates

Swift Bundle instruments model 5.3 will function some actually nice additions.


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

Localized assets

SE-0278 extends the useful resource assist, with this implementation you’ll be able to declare localized assets to your Swift packages. The outline explains nicely the proposed construction, you need to have a look in case you are interested by transport localized information along with your bundle.

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 need to ship closed supply code can now benefit from this function. This may make it doable to have a binaryTarget dependency at a given path or location and you should use the binary as a product in a library or executable.

Conditional Goal Dependencies

SE-0273 provides us a pleasant little addition so we are able to use dependencies based mostly on given platforms. Which means that you should use a product for a goal whenever you construct for a selected platform.

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

Language options

There are various new fascinating proposals that obtained into the 5.3 model.

A number of Trailing Closures

SE-0279 is among 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 remove a number 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 largely a syntactic sugar, however I satisfied myself that it’s good to have.

Synthesized Comparable conformance for enum varieties

Enum varieties do not must explicitly implement the Comparable protocol due to SE-0266.

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

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

Enum instances as protocol witnesses

Swift enums are loopy highly effective constructing blocks and now they only obtained higher. ?

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

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

The principle objective of SE-0280 to elevate an current restriction, this manner enum instances might be protocol witnesses if they supply the identical case names and arguments because the protocol requires.

Kind-Based mostly Program Entry Factors

SE-0281 provides us a brand new @important attribute that you should use to outline entry factors to your apps. It is a welcome boost, you do not have to jot down the MyApp.important() methodology anymore, however merely mark the MyApp object with the primary attribute as a substitute.

class AppDelegate: UIResponder, UIApplicationDelegate {

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

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

Multi-Sample Catch Clauses

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

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

This eliminates the necessity of utilizing a swap 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 capabilities are additionally coming quickly…

Self modifications

SE-0269 aka. Improve availability of implicit self in @escaping closures when reference cycles are unlikely to happen is a pleasant addition for individuals who do not like 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)

This may permit us to jot down self within the seize record solely and omit it afterward contained in the block.

Refine didSet Semantics

SE-0268 is an beneath the hood enchancment to make didSet conduct 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’s going to be solely invoked if we use to the oldValue parameter in our didSet block.

Add Assortment Operations on Noncontiguous Parts

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, you need to have a look in case you are working lots with ranges. ?

The place clauses on contextually generic declarations

With SE-0267 you can implement capabilities 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 may not compile on older variations, nevertheless 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 short 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 methodology you do not have to fiddle with unsafe pointers anymore.

Future evolution of Swift

At present there are 6 extra accepted proposals on the Swift evolution dasboard and one is beneath evaluate. Swift 5.3 goes to comprise some wonderful new options that had been lengthy awaited by the neighborhood. I am actually comfortable that the language is evolving in the proper course. ?


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