Enhance Debugging in Swift with #file, #line, and #function

Published at

12/4/2024

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Swift provides three special literals: #file, #line, and #function. These are automatically set to the current file name, line number, and function name, respectively. They are especially handy when creating custom logging functions or test predicates.

import Foundation

func log(_ message: String, _ file: String = #file, _ line: Int = #line, _ function: String = #function) {
    print("[\(file):\(line)] \(function) - \(message)")
}

func foo() {
    log("Hello world!")
}

foo() // [TryDebug.playground:8] foo() - Hello world!

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Enhance Debugging in Swift with #file, #line, and #function