When adding a method to a class, why do I not have to identify the Type that the result should return?

Question

I completed the challenge for adding the method to the Button class. However, when I initially created the method, I was declaring the Type that the function should return. Here is the first revision:
//
func incrementBy (points: Double) -> Double {
       width = self.width + points
       height = self.height + points
}
//
Why do you not have to include '-> Double' in the method? Up until now I have declared the Type that the function needs to return.
```Button.swift
class Button {
  var width: Double
  var height: Double
  init(width:Double, height:Double){
    self.width = width
    self.height = height
  }
  func incrementBy(points: Double) {
      width = self.width + points
      height = self.height + points
  }
}
```

Joshua Rapoport · Answer

You don't have to add the return typeat the end of the function declaration, mainly because within that function, you don't have to return anything.  If you're using a function to edit of value, and unless you are actually "return"ing  A double value, there's no need for "-> Type"
In this exercise, you're  editing the values of two properties, and while you are returning a new value to those properties, the function itself is returning no value at all.

Welcome to the Treehouse Community

Looking to learn something new?

Matt Frerichs

Matt Frerichs

When adding a method to a class, why do I not have to identify the Type that the result should return?

1 Answer

Joshua Rapoport

Joshua Rapoport

Matt Frerichs

Matt Frerichs