Скачать или смотреть How to Show an Alert in SwiftUI MVVM After a Login Function Failure

Learn how to effectively manage alerts in `SwiftUI` using the MVVM architecture, specifically after a user login attempt fails due to invalid credentials.
---
This video is based on the question https://stackoverflow.com/q/65913214/ asked by the user 'Charas' ( https://stackoverflow.com/u/4608714/ ) and on the answer https://stackoverflow.com/a/65913307/ provided by the user 'Asperi' ( https://stackoverflow.com/u/12299030/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: SwiftUI MVVM how to show alert after a function

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Handling Alerts in SwiftUI MVVM

Creating a user-friendly login page is an essential part of app development. One common challenge developers face is displaying alerts when login attempts fail, especially when using the MVVM architecture in SwiftUI. This guide will walk you through how to handle alerts properly so that you can guide users when they enter incorrect login information.

The Problem

You might have encountered a situation where you've built a login page using SwiftUI's MVVM architecture. After users click the login button, you want to show an alert if they have entered an empty text field or if their username/password combination is incorrect. However, if you've noticed that your alert does not display despite setting a state variable, you're not alone. This is a common issue, and we can solve it.

Example Code

Here's a simplified code snippet of what you might have:

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

The Solution

The main issue revolves around how you're handling the login functionality and how you notify SwiftUI of state changes. Here are some important steps to ensure your alert displays correctly:

Step 1: Update the Login Logic

You need to make sure that you call the completion handler for failure cases in your login function, so that the LoginView can properly update the alert state.

Modify your login function within the LoginViewModel class like this:

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

Step 2: Ensure UI State Updates on the Main Queue

Always make sure that UI updates happen on the main dispatch queue. This is crucial since UI operations need to be executed on the main thread to avoid any race conditions or inconsistencies in your app.

Summary

By incorporating these modifications, you will set your app up to display alerts correctly when login attempts fail due to invalid credentials. Always test your implementations and ensure that your view reflects the intended logic accurately.

Now, you have a robust way to inform users when login attempts do not succeed, enhancing user experience and guiding them smoothly through the login process.

If you have any further questions or need additional assistance with SwiftUI or MVVM design patterns, feel free to ask in the comments below!