Want to build Swift apps? Then, we can tell you from experience that solid code is your foundation. Effective code reviews are key whether aiming for App Store success or simply wanting to ship faster. Utilizing code reviews will help you catch errors early, maintain high performance, and produce an enjoyable codebase to work with. This article showcases a Swift code review checklist that will allow you to streamline your processes and quickly build better apps. We’ll cover all of the essentials, including:
Code Clarity and Style
Treat your Swift code as if you were in conversation with other developers or your future self. Clean code fast-tracks understanding, slashes debugging time, and future-proofs your Swift app. Code style isn’t just about looking pretty; it’s about making your apps rock-solid and your team super-efficient.
Key Best Practices:
- Use the official Swift style guide and coding conventions
- Name clearly and descriptively (camelCase for variables/functions, PascalCase for types)
- Prioritize code readability and simplicity
- Structure code logically using extensions, protocols, and appropriate access control
- Document complex logic and public APIs using Swift-style documentation comments
// Bad practice of function naming
func processData(arr: [Int]) -> [Int] {
// ... some complex data processing
return arr
}// Good practice of function naming
func calculateSquaredValues(inputNumbers: [Int]) -> [Int] {
// ... squares each number in the input array ...
return squaredNumbers
}Safety and Error Handling
Crashes and unexpected behavior are the fastest ways to frustrate users and sink your Swift app. Your reputation is at stake if a user loses data or hits a dead end because of a simple error.
Intelligent error handling in Swift prevents crashes, guides users through issues, and streamlines debugging.
Key Best Practices:
- Utilize Swift’s error handling (do-try-catch, Result) for error management
- Use Optionals to handle the absence of values and avoid forced unwrapping
- Implement input validation to prevent unexpected behavior and crashes
- Log errors and warnings effectively using Swift’s logging or custom logging solutions
- Consider using assertions and preconditions for debugging, as well as enforcing invariants during development
// Bad practice of do-try-catch
enum FileError: Error {
case notFound
case invalidFormat
}
func loadData(fromFile path: String) throws -> String {
// Imagine this function might throw FileError.notFound or FileError.invalidFormat
if path == "bad_path.txt" {
throw FileError.notFound
}
if path == "wrong_format.txt" {
throw FileError.invalidFormat
}
return "Data from \(path)" // Success case
}
func processFile(filePath: String) {
do {
try loadData(fromFile: filePath)
// ... imagine further processing of the loaded data ...
print("File processed successfully!")
} catch {
// Bad: Empty catch block - errors are silently ignored!
// No error handling at all.
}
}
// Example usage:
processFile(filePath: "bad_path.txt") // Prints "File processed successfully!" even though it should have failed!// Good practice of do-try-catch
enum FileErrorGood: Error {
case notFound
case invalidFormat
case unknown(Error) // To capture unexpected errors
}
func loadDataGood(fromFile path: String) throws -> String {
// ... (same file loading logic as before, but using FileErrorGood) ...
if path == "bad_path.txt" {
throw FileErrorGood.notFound
}
if path == "wrong_format.txt" {
throw FileErrorGood.invalidFormat
}
return "Data from \(path)"
}
func processFileGood(filePath: String) {
do {
let data = try loadDataGood(fromFile: filePath)
// ... process data ...
print("File processed successfully with data: \(data)")
} catch let error as FileErrorGood { // Good: Catch specific FileErrorGood type
switch error {
case .notFound:
print("Error: File not found at path: \(filePath)")
case .invalidFormat:
print("Error: File has an invalid format.")
case .unknown(let underlyingError): // Good: Handle unexpected errors
print("An unexpected file error occurred: \(underlyingError)")
}
} catch { // Good: Catch any other unexpected errors (as a fallback)
print("An unexpected error occurred: \(error)") // Good: Log or display a general error message
}
}
// Example usage:
processFileGood(filePath: "bad_path.txt")
// Output: Error: File not found at path: bad_path.txt
processFileGood(filePath: "good_path.txt")
// Output: File processed successfully with data: Data from good_path.txtPerformance and Resource Management
Performance is king in the Swift world, especially on iPhones and Macs. Users expect apps to be lightning-fast and smooth; with efficient code and resource management, you can effectively deliver that experience. Swift resource management supercharges app responsiveness, extends battery life, slims down memory usage, and unlocks effortless scaling.
Key Best Practices:
- Be mindful of value vs. reference types and their performance implications in Swift
- Optimize algorithms and data structures for efficiency
- Employ lazy loading and efficient data-fetching techniques
- Manage memory effectively, understanding Swift’s ARC (Automatic Reference Counting)
- Use profiling tools (like Instruments) to identify performance bottlenecks
- Where appropriate, consider concurrency and parallelism using Swift’s concurrency features (GCD, async/await, Actors)
// Bad practice of eager loading (loading upfront, even if not needed)
class MyViewController: UIViewController {
let largeImage = UIImage(named: "very_large_image.png")! // ❌ Eagerly loaded
override func viewDidLoad() {
super.viewDidLoad()
let imageView = UIImageView(image: largeImage)
// ... rest of setup ...
}
}// Good practice of lazy loading (loading only when needed)
class MyViewController: UIViewController {
lazy var largeImageView: UIImageView = { // ✅ Lazy loading using lazy var
let imageView = UIImageView()
imageView.image = UIImage(named: "very_large_image.png")
return imageView
}()
override func viewDidLoad() {
super.viewDidLoad()
// largeImageView is NOT loaded yet!
// ... later, when you need to display it:
view.addSubview(largeImageView) // ✅ Image is loaded NOW, when imageView is accessed
// ... rest of setup ...
}
}Security and Dependencies
Security is paramount for Swift apps, especially those handling user data or connecting to networks. Managing dependencies is your first line of defense. Swift security and dependency management build user trust, prevent attacks, protect data, and improve app stability.
Key Best Practices:
- Sanitize user input to prevent injection vulnerabilities (especially in web-related Swift contexts or when interacting with external systems)
- Use secure coding practices for data storage (Keychain for sensitive data on Apple platforms)
- Ensure secure network communication (HTTPS)
- Manage dependencies using Swift Package Manager (SPM) or CocoaPods/Carthage
- Regularly audit and update dependencies for security vulnerabilities
- Use dependency lock files (Package.resolved in SPM) for consistent builds
// Bad practice of ignoring package.resolved (not committing to version control)
MySwiftProject/
├── Package.swift // Defines dependencies
├── Sources/
│ └── ...Swift code...
└── .gitignore // ❌ Package.resolved is likely ignored here!// Good practice of committing package.resolved to version control
MySwiftProject/
├── Package.swift // Defines dependencies
├── Sources/
│ └── ...Swift code...
├── Package.resolved // ✅ Package.resolved IS committed!
└── .gitignoreTesting and Accessibility
What’s the point of excellent Swift code if it doesn’t work reliably or if users can’t properly utilize it? Robust Swift testing and accessibility practices empower you to build powerful, reliable, and inclusive apps that delight all users and catch issues early.
Key Best Practices:
- Write unit tests using XCTest to verify individual components
- Implement UI tests to validate user interface behavior
- Aim for reasonable test coverage, focusing on critical paths
- Use semantic UI elements in SwiftUI or UIKit for accessibility
- Incorporate accessibility attributes (UIAccessibility in UIKit, accessibility modifiers in SwiftUI)
- Test accessibility using VoiceOver and other accessibility tools
- Ensure keyboard navigation is supported (especially for macOS apps)
// Bad practice of non-semantic (accessibility Ignored)
import SwiftUI
struct BadAccessibilityButton: View {
var body: some View {
HStack { // ❌ HStack is visually grouping, not semantically a button
Image(systemName: "heart.fill") // ❌ Image alone has no semantic meaning
Text("Like") // ❌ Text alone is just text, not a button's action
}
.onTapGesture {
print("Like button tapped!")
}
}
}// Good practice of semantic SwiftUI with Accessibility Modifiers
import SwiftUI
struct GoodAccessibilityButton: View {
var body: some View {
Button { // ✅ Button is the semantic element for actions
print("Like button tapped!")
} label: {
Label("Like", systemImage: "heart.fill") // ✅ Label combines icon and text semantically
.labelStyle(.iconOnly) // ✅ (Optional) Style to show icon and text visually
}
.accessibilityLabel("Like") // ✅ Explicitly set accessibility label (redundant in this case, but good practice)
.accessibilityHint("Double tap to like this item") // ✅ Provide a hint for interaction
}
}Your Swift Development & Audit Services
Even basic applications can grow your business, and there is an audience of 5 billion mobile phone users worldwide. At Redwerk, we have two decades of mobile development expertise that can convert your idea into a flawless iOS app, an advanced Android app, or both.
Our Redwerk developers, designers, QA engineers, and project managers will jump right in to support your project. We make challenging tasks easier and deadlines less stressful. Here’s how our services empower clients to hit their goals:
- Ideation Development. We build custom software solutions from the ground up. See how we created an e-tutorship app, Gooroo, that matches the right tutors and students based on their profiles and expectations. This app got a 4.4-star App Store ranking.
- Code Refactoring. We specialize in code refactoring and elevate your code through today’s best practices. With a history of over 20 iOS app development projects in 7 countries, our team can modernize your codebase for improved performance and easier maintenance.
- Extending Functionality. We will increase the attractiveness of your product by adding new features or building easily scalable solutions. My Bike Valet, an intelligent bike parking system, leveraged our expertise in creating iOS and Android MVP architecture. We laid the ground for essential functionalities and kept the app scalable for advanced features.
- Hybrid & Cross-Platform App Development. Our Redwerk team builds top-notch native iOS and Android apps that are reliable and exactly what you need. Going native will ensure top speed and features. Going cross-platform will save you money and allow you to reach more users faster. We will guide you in making the best decision for your development and business goals.
We understand what it is like to have deadline pressure, as well as a need to move fast without wrecking your code. Whether you need a deep code audit, best practice advice, support throughout, or an entire development cycle, we’ve got the Swift pros to back you up. Ready to chat? We’re all ears to hear about your project and how we can help you nail it. Reach out anytime.
Read how we helped Quandoo build a fully functional iOS app, which now manages over 18,000 restaurants around the globe!
