How to Handle Fetch Requests in One View with SwiftUI: Merging Earnings and Spendings

Описание: Discover how to efficiently combine `Earnings` and `Spendings` views in SwiftUI into a unified structure by leveraging Core Data and fetch requests.
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Combining Fetch Requests in SwiftUI: A Guide to Merging Earnings and Spendings

When developing iOS applications, you may encounter situations where you have multiple views that serve similar functions but handle different data entities. This can lead to repeated code and increased maintenance efforts. In this guide, we’ll explore how to effectively merge two identical views—EarningsView and SpendingsView—into a single view in SwiftUI using Core Data, streamlining your code and enhancing manageability.

The Challenge

In our scenario, we initially have two views handling separate Core Data entities:

Earnings - Managed by EarningsView that deals with the Earning entity.

Spendings - Managed by SpendingsView that deals with the Spending entity.

Aside from their distinct data handling, both views share a significant amount of functionality, such as displaying lists and handling additional data input. Our goal is to create a unified CombinedView that can accommodate both types of transactions without modifying the high-level structure.

The Solution

Step 1: Create a Transaction Model

To facilitate this consolidation, we can introduce a general data model to encapsulate both earnings and spendings. Here’s a simple structure to represent our transactions:

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

Step 2: Update ContentView with Fetch Requests

Next, we modify the ContentView to include both fetch requests. Instead of managing two separate views directly, we will filter and display both earnings and spendings using a single structure.

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

Step 3: Implement the CombinedView

In the CombinedView, we can create a generic implementation that works with either type of transaction. Here’s how you can set it up:

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

Important Considerations

Dynamic Code Handling: Make sure to dynamically handle adding new transactions, including distinguishing between earnings and spendings based on the selected tab.

Core Data Classes: Note that enum types cannot be stored directly in Core Data. Instead, you could use the enum’s rawValue for your predicates and data handling.

Conclusion

By combining different fetch requests into a single view, we simplify our SwiftUI application’s structure and reduce redundancy. The approach demonstrated here serves as a robust framework that can easily be expanded for more complex scenarios.

Whether you're developing a financial tracking app or any similar use case, this method will help streamline your views while maintaining clear separations of responsibilities for different data entities. Now you can create engaging and efficient interfaces in SwiftUI with ease!