Use the Nil Coalescing Operator in Swift to assign default values to properties

One of the new operators that comes with Swift is the Nil Coalescing Operator. In the documentation it is explained as: The nil coalescing operator (a ?? b) unwraps an optional a if it contains a value, or returns a default value b if a is nil.

This operator already exited in C but for Objective-C developers it is kind of new (more about that at the bottom of this post).

With this operator assigning values to a property with a fallback to a default value becomes really concise:

Instead of doing this:

func setupBackgroundColor(color: UIColor?) {
   if (color != nil) {
      backgroundColor = color
   } else {
      backgroundColor = UIColor.whiteColor()
   }
}

You can simply do this:

func setupBackgroundColor(color: UIColor?) {
        backgroundColor = color ?? UIColor.whiteColor()
}

Pretty cool, isn’t it?

Actually something like this was already possible with Objective C:

- (void)setupBackgroundColor:(UIColor *)color {
   self.backgroundColor = color ? : [UIColor whiteColor];
}