Swift error: missing argument label 'name:' in call
swift
Solution
Swift functions can specify local and external argument names:
func greet(who name: String = "world") {
println("hello \(name)")
}
// prints "hello world"
greet()
// prints "hello jiaaro"
greet(who:"jiaaro")
// error
greet("jiaaro")
// error
greet(name: "jiaaro")
To opt out of this behavior you can use an underscore for the external name. Note that the first parameter implicitly uses the "no external name" behavior:
func greet(name: String = "world", _ hello: String = "hello") {
println("\(hello) \(name)")
}
// prints "hello world"
greet()
// prints "hello jiaaro"
greet("jiaaro")
// prints "hi jiaaro"
greet("jiaaro", "hi")
// error
greet(name: "jiaaro")
The following is now disallowed in Swift 2.0, see below for equivalent code.
You can use the `#` prefix to use the same local and external name for the first parameter:
func greet(#name: String = "world", hello: String = "hello") {
println("\(hello) \(name)")
}
// prints "hi jiaaro"
greet(name: "jiaaro", hello: "hi")
Swift 2.0 code:
func greet(name name: String = "world", hello: String = "hello") {
println("\(hello) \(name)")
}
// prints "hi jiaaro"
greet(name: "jiaaro", hello: "hi")
Problem
I'm learning about default arguments and I ran aground of something weird: ``` import UIKit func greet(name: String = "world") { println("hello \(name)") } greet("jiaaro") ``` this throws an error: ``` Playground execution failed: error: <REPL>:9:7: error: missing argument label 'name:' in call greet("jiaaro") ^ name: ``` I understand that it wants `greet(name: "jiaaro")` but I don't understand why that should be necessary.