Скачать или смотреть A Step-by-Step Guide to Creating a SwiftUI Calculator with Continuous Calculation

Learn how to build a SwiftUI calculator that performs continuous calculations just like a regular calculator. In this post, we will walk through the required code changes to enable seamless calculations.
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A Step-by-Step Guide to Creating a SwiftUI Calculator with Continuous Calculation

Introduction

Creating an iOS calculator app in SwiftUI is an exciting project, especially when aiming for a smooth and realistic user experience similar to that of an actual calculator. One of the critical functionalities of a calculator is the ability to perform continuous calculations without having to press the equals button after every operation. In this guide, we will discuss how to implement this feature and solve a common issue related to updating the displayed value upon tapping the operation buttons.

The Problem: Continuous Calculation

When developing your calculator, you may find that after pressing an operation button (like add or subtract), the result isn't displayed automatically. Instead, users have to press the equals button to see the calculated result. This breaks the flow of use and creates an inconvenient experience.

Current Code Behavior

In the existing setup, tapping an operation button only sets the state for the current operation but does not perform any calculation. As a result, the display will not show partial results, leading to confusion and frustration for users trying to perform consecutive calculations.

Solution Overview

To create a SwiftUI calculator that allows for continuous calculations, we need to modify the code in the following ways:

Track Current Operation and Values: Introduce variables that keep track of the last result, the current operation, and whether a new number is being input after an operation.

Calculate Partial Results: Whenever an operation button is pressed, calculate and display the intermediate result, allowing users to immediately see the impact of their actions.

Update Number Input Logic: Adjust the logic for how numbers are input to facilitate continuous calculations seamlessly.

Implementing the Changes

Now, let's walk through the required code changes step-by-step.

Step 1: Modify State Variables

We will change some state variables to improve clarity and manageability:

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

Step 2: Update the Button Logic

In the didTap function, we must ensure that each time we press an operator, we set the current result and prepare for a new number entry:

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

Step 3: Implement the Result Calculation

Create a function to calculate and update the display number based on previous results and the selected operations:

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

Final Code

After implementing all necessary changes, you will have a functioning calculator that can perform continuous calculations with ease. Here’s what your final ContentView might look like:

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

Conclusion

With these modifications, your SwiftUI calculator will now behave more intuitively, allowing users to see partial results immediately after performing operations. This presents a more modern and responsive user experience, similar to that of traditional calculators.

Feel free to expand this basic framework by adding more complex operations or features, such as backspace functionality or displaying past calculations. Happy coding!