How to Delay API Calls in SwiftUI Until Required Data Is Available

Learn how to manage API calls in SwiftUI based on user input validation, improving user experience and avoiding default data display.
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Understanding the Problem: SwiftUI API Call Timing

Are you developing a SwiftUI application that fetches data from an API, but the data is being fetched too early, resulting in default data being displayed first? You're not alone! Many developers face similar challenges while managing asynchronous API calls, especially when relying on user input from text fields.

In this guide, we'll walk through a solution that allows you to control when an API request is made based on user input. This ensures that your app only displays relevant data when the necessary information is provided.

The Challenge at Hand

In the code shared by the user, a love calculator app is made using SwiftUI and an external API. The issue is that the API request is being executed as soon as the view appears, regardless of whether the user has entered the required names. This results in default data being shown before the actual data can be displayed.

Key Concerns

How to make the API call conditionally based on user input.

Setting up a variable that flags when both input fields are filled.

Making the -Published variable for storing API results optional.

Solution Breakdown

Let's explore the steps to manage API calls effectively in SwiftUI:

1. Control API Calls with Computed Variables

Instead of using the .task modifier directly on the view, we can create a computed property that evaluates whether both inputs have been filled in.

Example Solution:

[[See Video to Reveal this Text or Code Snippet]]

Key Adjustments:

A computed variable namesAreValid checks that both text fields are populated.

Use the .onChange modifier to trigger the API call only when both names are available.

2. Optionally Initialize Your -Published Variable

If you want to avoid initializing your -Published var loveData with default values, you can make it optional by changing its type to LoveData?.

Modification to LoveViewModel:

[[See Video to Reveal this Text or Code Snippet]]

Handling Optional Data:

In LoveResults, ensure that optional values are guarded, and provide fallback values:

[[See Video to Reveal this Text or Code Snippet]]

Final Thoughts

Managing API calls based on user input can help create a cleaner user experience in your applications. By implementing conditional API requests and using optional data structures, you can prevent displaying irrelevant information to users and enhance the functionality of your SwiftUI app.

Feel free to experiment with this approach and adjust it according to your app's requirements. Happy coding!