The swift version I will be talking about is 5.9. As every year, Apple continues to develop the Swift language this year. And Swift is stronger and more performant this year, just like every year. Below I will talk about the striking features of the new version of Swift with examples. Let&#8217;s start.
<h2><code class="language-text">if</code> and <code class="language-text">switch</code> Expressions (<a href="https://github.com/apple/swift-evolution/blob/main/proposals/0380-if-switch-expressions.md" target="_blank" rel="noopener">SE-0380</a>)</h2>
This feature introduces the ability to use if and switch statements as expressions, for the purpose of:
<ul class="ul1">
<li class="li1">Returning values from functions, properties, and closures (either implicit or explicit)</li>
<li class="li1">Assigning values to variables</li>
<li class="li1">Declaring variables</li>
</ul>
<img class="alignnone wp-image-4841" src="https://ac.appcircle.io/wp-content/uploads/2023/06/if-300x167.png" alt="if and switch Expressions" width="620" height="345" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/if-300x167.png 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/if-1030x574.png 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/if-768x428.png 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/if-705x393.png 705w, https://ac.appcircle.io/wp-content/uploads/2023/06/if.png 1120w" sizes="(max-width: 620px) 100vw, 620px" />
<img class="alignnone wp-image-4842" src="https://ac.appcircle.io/wp-content/uploads/2023/06/switch-300x284.png" alt="if and switch Expressions" width="621" height="588" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/switch-300x284.png 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/switch-1030x975.png 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/switch-768x727.png 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/switch-705x667.png 705w, https://ac.appcircle.io/wp-content/uploads/2023/06/switch.png 1040w" sizes="(max-width: 621px) 100vw, 621px" />
For an <code class="language-text">if</code> or <code class="language-text">switch</code> to be used as an expression, it would need to meet these criteria:
<ul>
<li>Each branch of the <code class="language-text">if</code>, or each case of the <code class="language-text">switch</code>, must be a single expression.</li>
<li>Each of those expressions, when type checked independently, must produce the same type.</li>
<li>In the case of <code class="language-text">if</code> statements, the branches must include an <code class="language-text">else</code>.</li>
</ul>
<h2>Generic improvement</h2>
Type inference makes APIs using parameter packs natural to use, without needing to know that the API is using them, i.e call-side might not even aware you are using type parameter pack under the hood.
<img class="alignnone wp-image-5811" src="https://ac.appcircle.io/wp-content/uploads/2023/06/ray-so-export-1-300x204.png" alt="Generic improvement" width="544" height="370" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/ray-so-export-1-300x204.png 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/ray-so-export-1-1030x702.png 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/ray-so-export-1-768x523.png 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/ray-so-export-1-1536x1047.png 1536w, https://ac.appcircle.io/wp-content/uploads/2023/06/ray-so-export-1-1500x1022.png 1500w, https://ac.appcircle.io/wp-content/uploads/2023/06/ray-so-export-1-705x480.png 705w, https://ac.appcircle.io/wp-content/uploads/2023/06/ray-so-export-1.png 1840w" sizes="(max-width: 544px) 100vw, 544px" />
Enabling generic abstraction over argument length <code>&lt;each Result&gt;</code> know as type parameter pack (multiple individual type parameters that are “packed” together)
<h2>Convenience AsyncStream.makeStream methods (<a href="https://github.com/apple/swift-evolution/blob/main/proposals/0388-async-stream-factory.md" target="_blank" rel="noopener">SE-0388</a>)</h2>
This feature adds a new static method makeStream on AsyncStream and AsyncThrowingStream that returns both the stream and the continuation, which make the stream’s continuation easier to access.
<img class="alignnone wp-image-4844" src="https://ac.appcircle.io/wp-content/uploads/2023/06/make-stream-300x223.png" alt="Convenience AsyncStream.makeStream methods" width="545" height="405" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/make-stream-300x223.png 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/make-stream-1030x766.png 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/make-stream-768x571.png 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/make-stream-1500x1115.png 1500w, https://ac.appcircle.io/wp-content/uploads/2023/06/make-stream-705x524.png 705w, https://ac.appcircle.io/wp-content/uploads/2023/06/make-stream.png 1504w" sizes="(max-width: 545px) 100vw, 545px" />
<h2>Custom Actor Executors (<a href="https://github.com/apple/swift-evolution/blob/main/proposals/0392-custom-actor-executors.md" target="_blank" rel="noopener">SE-0392</a>)</h2>
This proposal proposes a way to customize the executors of actors in Swift, which are responsible for scheduling and running tasks on actors. Executors are abstract types that conform to the Executor protocol and provide a enqueue(_:) method to submit tasks to be executed.
<img class="alignnone wp-image-4846" src="https://ac.appcircle.io/wp-content/uploads/2023/06/executors-300x160.png" alt="Custom Actor Executors" width="549" height="293" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/executors-300x160.png 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/executors-1030x551.png 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/executors-768x411.png 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/executors-1536x821.png 1536w, https://ac.appcircle.io/wp-content/uploads/2023/06/executors-1500x802.png 1500w, https://ac.appcircle.io/wp-content/uploads/2023/06/executors-705x377.png 705w, https://ac.appcircle.io/wp-content/uploads/2023/06/executors.png 1840w" sizes="(max-width: 549px) 100vw, 549px" />
This proposal also defines a SerialExecutor protocol, which is what actors use to guarantee their serial execution of tasks (jobs).
<img class="alignnone wp-image-4847" src="https://ac.appcircle.io/wp-content/uploads/2023/06/serial-executors-300x270.png" alt="SerialExecutor" width="547" height="492" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/serial-executors-300x270.png 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/serial-executors-1030x928.png 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/serial-executors-768x692.png 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/serial-executors-1536x1384.png 1536w, https://ac.appcircle.io/wp-content/uploads/2023/06/serial-executors-1500x1352.png 1500w, https://ac.appcircle.io/wp-content/uploads/2023/06/serial-executors-705x635.png 705w, https://ac.appcircle.io/wp-content/uploads/2023/06/serial-executors.png 1840w" sizes="(max-width: 547px) 100vw, 547px" />
All actors implicitly conform to the Actor (or DistributedActor) protocols. Those protocols include the customization point for the executor they are required to run on in form of the the unownedExecutor property.
<h2>Add sleep(for:) to Clock (<a href="https://github.com/apple/swift-evolution/blob/main/proposals/0374-clock-sleep-for.md" target="_blank" rel="noopener">SE-0374</a>)</h2>
There is currently a slight imbalance between the sleep APIs for clocks and tasks, and it causes some troubles when dealing with Clock existentials.<img class="alignnone wp-image-4848" src="https://ac.appcircle.io/wp-content/uploads/2023/06/clock-ex-300x94.png" alt="Add sleep(for:) to Clock" width="552" height="173" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/clock-ex-300x94.png 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-ex-1030x324.png 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-ex-768x241.png 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-ex-1536x483.png 1536w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-ex-1500x471.png 1500w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-ex-705x221.png 705w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-ex.png 1840w" sizes="(max-width: 552px) 100vw, 552px" />
This release introduce a <code class="language-text">sleep(for:)</code> method that only dealt with durations, and not instants, then we could invoke that API on an existential:
<img class="alignnone wp-image-4849" src="https://ac.appcircle.io/wp-content/uploads/2023/06/clock-300x131.png" alt="Add sleep(for:) to Clock" width="552" height="241" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/clock-300x131.png 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-1030x450.png 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-768x336.png 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-1536x671.png 1536w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-1500x655.png 1500w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock-705x308.png 705w, https://ac.appcircle.io/wp-content/uploads/2023/06/clock.png 1840w" sizes="(max-width: 552px) 100vw, 552px" />
<h2>C++ Interoperability</h2>
We used to implement Swift ↔ Objective-C ↔ C++ to use C++ language. Swift now has direct access to C++. In this way, we will be able to benefit from the power of the C++ language more easily and quickly.
<img class="alignnone wp-image-5809" src="https://ac.appcircle.io/wp-content/uploads/2023/06/cplus-plus-300x131.jpeg" alt="C++ Interoperability" width="550" height="240" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/cplus-plus-300x131.jpeg 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/cplus-plus-1030x449.jpeg 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/cplus-plus-768x335.jpeg 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/cplus-plus-1536x670.jpeg 1536w, https://ac.appcircle.io/wp-content/uploads/2023/06/cplus-plus-2048x893.jpeg 2048w, https://ac.appcircle.io/wp-content/uploads/2023/06/cplus-plus-1500x654.jpeg 1500w, https://ac.appcircle.io/wp-content/uploads/2023/06/cplus-plus-705x308.jpeg 705w" sizes="(max-width: 550px) 100vw, 550px" />
Its use is as simple as shown below!
<img class="alignnone wp-image-5810" src="https://ac.appcircle.io/wp-content/uploads/2023/06/plus-plus-300x161.jpg" alt="C++ Interoperability example" width="551" height="296" srcset="https://ac.appcircle.io/wp-content/uploads/2023/06/plus-plus-300x161.jpg 300w, https://ac.appcircle.io/wp-content/uploads/2023/06/plus-plus-1030x553.jpg 1030w, https://ac.appcircle.io/wp-content/uploads/2023/06/plus-plus-768x412.jpg 768w, https://ac.appcircle.io/wp-content/uploads/2023/06/plus-plus-1536x825.jpg 1536w, https://ac.appcircle.io/wp-content/uploads/2023/06/plus-plus-2048x1099.jpg 2048w, https://ac.appcircle.io/wp-content/uploads/2023/06/plus-plus-1500x805.jpg 1500w, https://ac.appcircle.io/wp-content/uploads/2023/06/plus-plus-705x378.jpg 705w" sizes="(max-width: 551px) 100vw, 551px" />
Yes, that&#8217;s how some standout headers were in Swift. Swift has many more improvements. To see more details, you can watch the <a href="https://developer.apple.com/videos/play/wwdc2023/10164" target="_blank" rel="noopener">session video</a> or read the <a href="https://www.swift.org/swift-evolution/" target="_blank" rel="noopener">swift-evoulation</a> document.
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