[Solved] Swift 4 custom argument labels – required? [closed]

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In Swift each function parameter can have both argument label and a parameter name.

  1. argument label: used in function call
  2. parameter name: used inside the function definition

By default, parameters use their parameter name as their argument label.

These are the possible function declarations that can be used in swift:

Case 1: parameter name is same as the argument label

func greet (person: String, day: String) -> String {
    return "Hello \(person) on \(day)"
}

Function Call: greet(person: "John", day: "23")

Case 2: different parameter name and argument label

func greet (person person: String, on day: String) -> String {
    return "Hello \(person) on \(day)"
}

Function Call: greet(person: "John", on: "23")

Case 3: using _ as argument label

func greet (_ person: String, _ day: String) -> String {
    return "Hello \(person) on \(day)"
}

Function Call: greet("John", "23")

For more on how function parameters work, you can refer to: https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Functions.html

Let me know if you still face any issues.

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solved Swift 4 custom argument labels – required? [closed]