Building SwiftUI Debugging Utilities

In this post, we will explore how to create debugging utilities in SwiftUI to help diagnose and fix issues in your app.

Printing values

As you may know already you cannot use print() directly in your SwiftUI code.

struct ContentView: View {
    var body: some View {
        Text("Hello, World!")
        let _ = print("This is a debug message") // Print in the supported way
    }
}

A way to achieve this functionality is creating a extension on View.

extension View {
    func print(_ value: Any) -> Self {
        Swift.print(value) // Swift.print to tell Swift that we want to use the native print function
        return self
    }
}

now we can use:

struct ContentView: View {
    var body: some View {
        Text("Hello, World!")
            .print("This is a debug message")
    }
}

Perform custom debugging actions

Sometimes you want to execute code only on the debug build.
One way is:

struct ContentView: View {
    var body: some View {
        Text("Hello, World!")
#if DEBUG
            .print("This is a debug message")
#endif
    }
}

A better way to achieve this functionality is creating a extension on View.

extension View {
    func debugAction(_ closure: () -> Void) -> Self {
        #if DEBUG
        closure()
        #endif

        return self
    }
}

now we can use:

struct ContentView: View {
    var body: some View {
        Text("Hello, World!")
            .debugAction {
                print("This is a debug message")
            }
    }
}

Debugging view borders

Sometimes you want to see where the views are located on the screen. You can achieve this by adding borders to your views.

extension View {
    func debugBorder(_ color: Color = .red) -> some View {
#if DEBUG
        self.border(color, width: 2)
#else
        self
#endif
    }
}

Now we can use:

struct ContentView: View {
    var body: some View {
        Text("Hello, World!")
            .debugBorder()
    }
}

Conclusion

Writing a pair of functions to print debug messages and add borders to views can greatly enhance the debugging experience in SwiftUI. By using conditional compilation and view extensions, we can create a clean and efficient debugging workflow.

Read more

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• SwiftUI ViewModifiers • 6 minutes reading time.

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