What are error handling patterns for SwiftUI in Swift?

SwiftUI provides a variety of ways to handle errors effectively while building user interfaces. Here are some common error handling patterns in SwiftUI:

Using Try-Catch in ViewModels

Encapsulate your state management and error handling within a ViewModel using Swift's traditional try-catch mechanism:


        class MyViewModel: ObservableObject {
            @Published var data: String = ""
            @Published var errorMessage: String?
            
            func fetchData() {
                do {
                    // Example function that can throw an error
                    data = try loadData() 
                } catch {
                    errorMessage = "Failed to load data: \(error.localizedDescription)"
                }
            }
            
            func loadData() throws -> String {
                // Simulate a possible error
                throw NSError(domain: "", code: 1, userInfo: [NSLocalizedDescriptionKey: "Data not found"])
            }
        }

Using Result Type

Another pattern is to use the Result type to encapsulate success or failure in your async operations:


        class MyViewModel: ObservableObject {
            @Published var result: Result?
            
            func fetchData() {
                fetchDataAsync { result in
                    DispatchQueue.main.async {
                        self.result = result
                    }
                }
            }

            func fetchDataAsync(completion: @escaping (Result) -> Void) {
                // Simulate an async fetch operation
                completion(.failure(NSError(domain: "", code: 1, userInfo: [NSLocalizedDescriptionKey: "Data not found"])))
            }
        }

Displaying Errors in the View

In your SwiftUI view, you can conditionally show error messages based on your ViewModel's state:


        struct ContentView: View {
            @StateObject var viewModel = MyViewModel()

            var body: some View {
                VStack {
                    if let errorMessage = viewModel.errorMessage {
                        Text(errorMessage)
                            .foregroundColor(.red)
                    } else {
                        Text(viewModel.data)
                    }
                }
                .onAppear {
                    viewModel.fetchData()
                }
            }
        }

SwiftUI error handling Swift ViewModel try-catch Result type

What are error handling patterns for SwiftUI in Swift?

Using Try-Catch in ViewModels

Using Result Type

Displaying Errors in the View

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What are error handling patterns for SwiftUI in Swift?

Using Try-Catch in ViewModels

Using Result Type

Displaying Errors in the View

Related Questions

Popular Topics

Recent Languages