How to create a filtered search experience in Swift

Oscar de la Hera Gomez
A flower that represents Swift next to a flower that represents XCode. Beneath it sits the text that states 'Filtered Search'.

A step by step tutorial on making a filtered search experience in Swift (iOS). Github repository included.

The following tutorial walks you through how to filter through the data of a UICollectionView and present it to the user. It builds off our Swift Open Source starter project and starts on the tutorial/custom/searchbar branch with all relevant changes found on the tutorial/custom/filtered-search branch.

Please note that this tutorial builds of a series of tutorials listed below destined at creating a Swift starter project, setting it up for API calls, making a GraphQL API call and visualizing the results through a data driven UICollectionView.

Please note this tutorial uses the TinyConstraints Swift package, which we added using the Swift Package Manager.

Tutorial

Step One: Declare your filtered data variable

A screenshot showing how we declared the filtered data array within the CustomUIView.swift.

In CustomUIView.swift, declare your filtered data variable.

Please note that you are now required to import the API generated by the GraphQL and that the schema has changed since the original writing of this post.

This is reflected by the code provided in the repo.

Step Two: Alter UICollectionView dataset based on state

A screenshot showing the code that is described step by step below that demonstrates how to alter the data that a collection view shows depending on the search bar search state.

The following step is aims to alter the data that's offered by the collection view depending on the search query. For this, we must alter the number of items offered and the data that is shown by the UICollectionView.

A | Alter the number of items

A screenshot showing you how to alter the number of items displayed by the collection view depending on the search bar search state.

In CustomUIView+CollectionView.swift, alter the number of items offered by the UICollectionview depending on the search state.

This can be found on line 26 in the collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int function.

B | Alter the data that is displayed

A screenshot demonstrating the code that is required to alter the data that is shown by the UICollectionView depending on the search bar search state.

In CustomUIView+CollectionView.swift, alter the data offered by the UICollectionview depending on the search state.

This can be found on line 43 in the func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell function.

The complete code can be found below.

Step Three: Create the filtered search algorithm

A screenshot of the code behind the filter algorithm. In this case we chose to filter the data based on whether the name or type of the Pokemon appears within the search query.

In the CustomUIView+Update.swift file, add a new function for your filtered data. We have made our complete extension available below.

Step Four: Create, send & receive the search query was update notification

A screenshot of the code that we used to create, send and receive the notification. This is detailed step by step below.

The following step aims to create a notification whose purpose is to let the system know that the search query was updated. We then send it, when the search text is updated and use it to process the new filter - via the function created in the previous step.

A | Create the notification

A screenshot of the code that we used to create the notification.

In SystemNotifications.swift, create a new notification called onSearchQueryWasUpdated.

B | Send the notification

A screenshot showing you the code of how we sent the notification when the search query is edited. We did this within the CustomUIView+TextField extension, within the function that is called every time the text changes. Additionally, its important to note that we sent the notification after updating the state.

In SearchBar+TextField.swift, in the onTextFieldDidUpdate function, after updating the state, send the notification that the query was updated.

Please note that this code has been updated to use our NotificationCoordinator.

C | Receive and Process the Notification

A screenshot of the observer and selector that was created in order to process the notification that gets sent when the search bar text gets updated.

In CustomUIView+Notifications.swift, create a new notification observer and selector. Within the selector, tell the app to update the data.

Step Five: Verify

A screenshot of an iPhone 13 demonstrating the product of the tutorial.

Run the app and see the UICollectionView change itself depending on the data.

Any Questions ?

We are actively looking for feedback on how to improve this resource. Please send us a note to inquiries@delasign.com with any thoughts or feedback you may have.
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