Free AI web copilot to create summaries, insights and extended knowledge, download it at here
3392
Abstract
er">17</span>]</pre></div><blockquote id="c020"><p>Compact Map()</p></blockquote><p id="b1c2"><code>compactMap</code> function is similar to <code>map</code>, but it also includes an additional step, it filters out any <code>nil</code> values that result from applying the transformation closure. This is particularly useful when you have an array of optional values and you want to transform them while simultaneously filtering out the <code>nil</code> elements.</p><div id="9cf9"><pre><span class="hljs-keyword">extension</span> <span class="hljs-title class_">Array</span> {
<span class="hljs-keyword">func</span> <span class="hljs-title function_">compactMap</span><<span class="hljs-type">T</span>>(<span class="hljs-keyword">_</span> <span class="hljs-params">transforms</span>: (<span class="hljs-type">Element</span>) -> <span class="hljs-type">T</span>?) -> [<span class="hljs-type">T</span>] {
<span class="hljs-keyword">var</span> result <span class="hljs-operator">=</span> <span class="hljs-type">T</span>
<span class="hljs-keyword">for</span> element <span class="hljs-keyword">in</span> <span class="hljs-keyword">self</span> {
<span class="hljs-keyword">if</span> <span class="hljs-keyword">let</span> element <span class="hljs-operator">=</span> element {
result.append(transform(element))
}
}
<span class="hljs-keyword">return</span> result
}
}</pre></div><p id="fe9c">Here the only change from <code>Map</code> and <code>Compact Map</code> is avoiding the nil value with a condition.</p><p id="3b42">In the above code</p><ul><li>It takes a closure <code>transform</code> as an argument, which specifies how each element should be transformed.</li><li>Inside <code>compactMap</code>, a new array <code>result</code> is created to store the transformed non-nil elements.</li><li>It then iterates over each element of the original array (<code>self</code>), applies the transformation closure to each element, and checks if the result is non-nil.</li><li>If the result is non-nil, it appends the transformed element to the <code>result</code> array.</li><li>Finally, it returns the <code>result</code> array containing all the non-nil transformed elements.</li></ul><blockquote id="9909"><p>How to consume it?</p></blockquote><div id="41f1"><pre><span class="hljs-keyword">let</span> mapArray <span class="hljs-operator">=</span> [<span class="hljs-number">23</span>, <span class="hljs-number">43</span>, <span class="hljs-number">56</span>, <span class="hljs-literal">nil</span>, <span class="hljs-number">75</span>, <span class="hljs-number">9</span>, <span class="hljs-number">14</span>]
<span class="hljs-keyword">let</span> result<span class="hljs-operator">=</span> mapArray.compactMap { <span class="hljs-variable">$0</span> }
<span class="hljs-built_in">debugPrint</span>(result)
output: [<span class="hljs-number">23</span>, <span class="hljs-number">43</span>, <span class="hljs-number">56</span>, <span class="hljs-number">75</span>, <span class="hljs-number">9</span>, <span class="hljs-number">14</span>]</pre></div><blockquote id="854c"><p>Flat Map()</p></blockquote><p id="b656">FlatMap is typically the same as <code>map</code> does, only difference is that it always return flatten array joining all elements. Typically used to collect specific data in n
Options
ested array, dictionary or set</p><div id="6431"><pre><span class="hljs-keyword">extension</span> <span class="hljs-title class_">Array</span> {
<span class="hljs-keyword">func</span> <span class="hljs-title function_">flatMap</span><<span class="hljs-type">T</span>>(<span class="hljs-keyword">_</span> <span class="hljs-params">transform</span>: (<span class="hljs-type">Element</span>) -> [<span class="hljs-type">T</span>]) -> [<span class="hljs-type">T</span>] {
<span class="hljs-keyword">var</span> result <span class="hljs-operator">=</span> <span class="hljs-type">T</span>
<span class="hljs-keyword">for</span> element <span class="hljs-keyword">in</span> <span class="hljs-keyword">self</span> {
result.append(contentsOf: transform(element))
}
<span class="hljs-keyword">return</span> result
}
}</pre></div><p id="75fa">In the above code</p><ul><li>It takes a closure <code>transform</code> as an argument, which specifies how each element should be transformed into a sequence.</li><li>Inside <code>flatMap</code>, a new array <code>result</code> is created to store the flattened elements.</li><li>It then iterates over each element of the original array (<code>self</code>), applies the transformation closure to each element, and concatenates the resulting sequences into the <code>result</code> array.</li><li><code>append(contentsOf: )</code> will add the elements of a sequence to the end of the array.</li><li>Finally, it returns the <code>result</code> array containing all the flattened elements.</li></ul><blockquote id="2285"><p>How to consume it?</p></blockquote><div id="117f"><pre><span class="hljs-keyword">let</span> arrayOfArrays <span class="hljs-operator">=</span> [[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>], [<span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>], [<span class="hljs-number">7</span>, <span class="hljs-number">8</span>, <span class="hljs-number">9</span>]]
<span class="hljs-keyword">let</span> transformedArray <span class="hljs-operator">=</span> arrayOfArrays.flatMap { <span class="hljs-variable">$0</span> }
<span class="hljs-built_in">print</span>(transformedArray)
output: [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>, <span class="hljs-number">9</span>]</pre></div><h1 id="3bda">Conclusion</h1><p id="057c">There are plenty of other use cases for higher-order functions. This is a gist of what we have discovered today:</p><ul><li>If you need to simply transform a value to another value, then use <code>map</code>.</li><li>If you need to remove nil values, then use <code>compactMap</code>.</li><li>If you need to flatten your result one level down, then use <code>flatMap</code>.</li></ul><p id="0a10">Thank you for your time and attention! 👏👏👏</p><p id="33e6">Do clap👏 if you like this and comment your suggestions!!! <i>Happy coding</i>!!!</p><blockquote id="1e0c"><p>Source Code: <a href="https://github.com/Vikassingamsetty/HigherOrderFunctions.git">GitHub</a></p></blockquote></article></body>
