10 SwiftUI Best Practices

If you're new to SwiftUI, or just looking to brush up on your skills, these best practices are a great place to start.

SwiftUI is a modern, declarative UI framework for iOS and MacOS development. It’s designed to make it easier to create user interfaces that are both beautiful and functional. SwiftUI is a great tool for developers to use, but it’s important to understand the best practices for using it.

In this article, we’ll discuss 10 SwiftUI best practices that will help you create better apps and make the most of SwiftUI’s features. We’ll cover topics like using the right view types, leveraging data binding, and more. By following these best practices, you’ll be able to create more efficient and maintainable SwiftUI apps.

1. Use @State and @Binding for managing state changes

@State is a property wrapper that allows us to store and manage state changes in our SwiftUI views. It’s used for storing values that can be changed by the user, such as text fields or toggle switches. When the value of a @State variable changes, it triggers an update to the view, which causes the UI to re-render with the new value. This makes it easy to keep track of changes in the UI without having to manually call setNeedsDisplay() every time something changes.

@Binding is similar to @State, but instead of creating its own storage, it uses an existing source of truth. This means that when the value of the binding changes, the view will automatically update with the new value. This is useful for passing data between different parts of the app, such as from a parent view to a child view. By using @Binding, we can ensure that all parts of the app are always up to date with the latest information.

Using @State and @Binding together is a great way to manage state changes in SwiftUI. They make it easy to keep track of changes in the UI and pass data between different parts of the app. Plus, they help ensure that the UI is always up to date with the latest information.

2. Use @EnvironmentObject to share data between views

@EnvironmentObject is a property wrapper that allows us to inject an object into the environment of any view in our SwiftUI hierarchy. This means that we can pass data from one view to another without having to manually pass it through each view in between.

Using @EnvironmentObject also helps keep our code clean and organized, as all of our shared data is stored in one place. We don’t have to worry about passing the same data around multiple times or creating duplicate copies of the same data. Instead, we just need to create one instance of the object and then use @EnvironmentObject to make sure it’s available everywhere.

The way this works is that when we create an instance of an object, we wrap it with the @EnvironmentObject property wrapper. Then, whenever we want to access the object, we simply call the .environmentObject() method on the current view. This will return the object that was injected into the environment earlier.

3. Prefer composition over inheritance

Composition is a way of combining objects or data types into more complex ones. It allows us to create new objects from existing ones without having to modify the existing objects themselves. This makes it easier to reuse code and keep our codebase DRY (Don’t Repeat Yourself).

By contrast, inheritance is a way of creating a class that inherits properties and behavior from another class. While this can be useful in some cases, it can also lead to tight coupling between classes, making them difficult to maintain and extend.

SwiftUI encourages composition over inheritance by providing powerful tools for composing views. For example, SwiftUI’s ViewBuilder lets you easily compose multiple views together into one view hierarchy. You can also use modifiers like padding(), background(), and font() to apply styling to any view. These features make it easy to build complex user interfaces out of simple components.

Furthermore, SwiftUI provides several APIs that make it easy to combine different kinds of data into one view. For example, the List API lets you display an array of items as a list, while the Form API lets you group related fields into a single form. By using these APIs, you can quickly assemble complex user interfaces with minimal effort.

4. Understand how view preferences affect the view hierarchy

View preferences are a way to pass data up the view hierarchy. They allow views lower in the hierarchy to communicate with their parent views, and can be used to customize the behavior of the parent view. For example, if you have a list of items that need to be displayed in a certain order, you could use a view preference to tell the parent view which item should be at the top of the list.

The key to understanding how view preferences affect the view hierarchy is knowing when and where to apply them. View preferences should only be applied to views that will be used as parents for other views. This ensures that the view preferences will be passed down to all child views. It also helps keep the view hierarchy organized and easy to understand.

When using SwiftUI, it’s important to think about how view preferences will affect the view hierarchy before adding them to your code. If you add view preferences without considering how they will affect the view hierarchy, you may end up with an unorganized or inefficient view hierarchy. Additionally, if you don’t consider how view preferences will affect the view hierarchy, you may find yourself having to rewrite large sections of code to accommodate changes in the view hierarchy.

5. Create custom modifiers to apply multiple styles at once

Custom modifiers are a great way to apply multiple styles at once because they allow you to group related styling properties together. This makes it easier to maintain and update the code, as all of the related style changes can be made in one place. For example, if you want to change the font size for a text view, you can create a custom modifier that sets both the font size and color, rather than having to make two separate calls to set each property individually.

Creating custom modifiers is also beneficial when working with complex views, such as lists or grids. By creating a single modifier that applies multiple styles, you can quickly and easily apply those same styles to every item in the list or grid. This saves time and effort compared to manually setting the style for each individual item.

To create a custom modifier, you first need to define a struct that conforms to the ViewModifier protocol. The body of this struct should contain the styling properties you wish to apply. You then call the modifier() method on your view, passing in an instance of the struct you just created. This will apply the styling properties defined in the struct to the view.

You can also use custom modifiers to add additional functionality to a view. For example, you could create a modifier that adds a tap gesture recognizer to a view, allowing it to respond to user input. This allows you to keep your view code clean and organized, while still adding extra features.

6. Leverage type-safe identifiers in ForEach loops

When using ForEach loops, it is important to use type-safe identifiers. This means that the identifier should be of a type that can uniquely identify each element in the loop. A common example of this would be an array of structs or classes with unique IDs. By leveraging type-safe identifiers, we are able to ensure that each item in the loop has a unique identifier and thus can be referenced correctly when needed.

Using type-safe identifiers also helps us avoid potential bugs related to incorrect references. For instance, if we were to use a non-type-safe identifier such as an index number, then there is a chance that two elements could have the same index number, leading to unexpected behavior. By using type-safe identifiers, we can guarantee that each element will have its own unique identifier and thus no confusion will arise.

Furthermore, by using type-safe identifiers, we can make our code more readable and maintainable. Since the identifier is of a specific type, it is easier for other developers to understand what the identifier represents and how it is used. Additionally, since the identifier is of a specific type, it is easier to debug any issues that may arise due to incorrect references.

7. Take advantage of Combine framework for asynchronous operations

The Combine framework is a reactive programming framework that provides an easy-to-use declarative Swift API for processing values over time. It allows developers to easily create and manipulate asynchronous data streams, which are essential when working with SwiftUI. This is because SwiftUI relies heavily on the use of bindings, which require up-to-date information in order to update the UI accordingly. The Combine framework makes it easier to manage these bindings by providing a unified way to handle asynchronous operations.

Using the Combine framework also helps keep code clean and organized. By using publishers and subscribers, developers can separate their logic into distinct components, making it easier to debug and maintain. Additionally, since the Combine framework is built on top of Apple’s Grand Central Dispatch (GCD) technology, it offers better performance than other solutions.

When using the Combine framework with SwiftUI, there are two main steps: creating a publisher and subscribing to it. To create a publisher, developers must first define a type of Publisher they want to use. For example, if they want to fetch data from a web service, they would use a URLSession.DataTaskPublisher. Once the publisher has been created, developers can then subscribe to it using one of the provided operators such as sink or assign. These operators will take care of updating the UI whenever new data is received.

8. Use GeometryReader when working with dynamic layout

GeometryReader is a container view that defines its own coordinate space for its content. It allows us to access the size and position of its frame, which can be used to create dynamic layouts based on the available space. This makes it ideal for creating adaptive user interfaces that adjust their layout depending on the device or orientation.

Using GeometryReader also helps keep our code clean and organized by allowing us to separate out the layout logic from the rest of the view’s code. We can define all of our layout calculations in one place, making them easier to maintain and debug.

When using GeometryReader, we can use the geometry parameter to access the size and position of the view’s frame. This allows us to calculate the sizes and positions of other views relative to the GeometryReader’s frame. For example, if we want to center a view within the GeometryReader’s frame, we can use the width and height properties of the geometry parameter to calculate the exact coordinates needed to do so.

We can also use the safeAreaInsets property of the geometry parameter to account for any additional insets introduced by the system (such as the notch on an iPhone X). This ensures that our UI elements are always positioned correctly regardless of the device or orientation.

9. Avoid force unwrapping optionals unless absolutely necessary

Force unwrapping optionals is a way of accessing the value stored inside an optional without checking if it contains a value or not. This can be done by adding an exclamation mark (!) after the variable name, which will cause the program to attempt to access the value regardless of whether it exists or not. If the optional does not contain a value, this will result in a runtime error and crash the app.

To avoid force unwrapping optionals, SwiftUI provides several methods for safely accessing values from optionals. The most common method is using the “if let” statement, which checks if the optional contains a value before attempting to access it. If the optional does contain a value, then the code within the “if let” block will execute; otherwise, the code will be skipped. This ensures that the app won’t crash due to trying to access a nil value.

SwiftUI also provides the “guard let” statement, which works similarly to the “if let” statement but with one key difference: if the optional does not contain a value, the guard let statement will exit the current scope instead of executing any code. This makes it useful for ensuring that certain conditions are met before continuing with the rest of the code.

The last method provided by SwiftUI for avoiding force unwrapping optionals is the “nil coalescing operator” (??). This operator allows you to provide a default value that will be used if the optional does not contain a value. This is useful for providing a fallback value in case the optional is nil, thus preventing the app from crashing.

10. Prefer SwiftUI’s native components over UIKit/AppKit equivalents

SwiftUI is designed to be a declarative UI framework, meaning that it allows developers to define the desired state of their user interface and then have SwiftUI take care of the rest. This means that when using SwiftUI, developers should strive to use native components whenever possible in order to get the most out of the framework.

Using native components has several advantages over using UIKit/AppKit equivalents. For one, native components are more likely to be optimized for performance since they are built specifically for SwiftUI. Additionally, native components often provide better integration with other parts of the SwiftUI framework, such as data binding and animation. Finally, native components tend to be easier to work with since they are designed to fit into the SwiftUI paradigm.

When working with SwiftUI, developers should always look for ways to use native components instead of UIKit/AppKit equivalents. If there isn’t an existing component that meets the needs of the project, developers can create custom views by combining existing components or creating new ones from scratch. Custom views can also be used to extend the functionality of existing components, allowing developers to customize them to meet their specific needs.


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