Update 'Home'

Home.md

@@ -452,7 +452,10 @@ Swift is strongly-typed, so we need to use the same number type for every argume
 
 ## Building the menu
 
-Back in our `updateIcon()` function, we're first going to create a new dictionary to hold our filter results. Then we're going to populate this dictionary by calling [`Dictionary.filter()`](https://developer.apple.com/documentation/swift/dictionary/filter(_:)) with our fitler function, `findPhase()`.
+Back in our `updateIcon()` function, we're first going to create a new dictionary to hold our filter results. Then we're going to populate this dictionary by calling [`Dictionary.filter()`](https://developer.apple.com/documentation/swift/dictionary/filter(_:)) with our filter function, `findPhase()`.
+
+We can use the special variable `$0` to access the array element currently running through our `findPhase()` filter function. Since our function takes [`Double`](https://developer.apple.com/documentation/swift/double) numbers as arguments, we'll convert the string value in `phaseArray` to a [`Double`](https://developer.apple.com/documentation/swift/double) - this is why we used [`NSString`](https://developer.apple.com/documentation/foundation/nsstring) instead of [`String`](https://developer.apple.com/documentation/swift/string) as the values in `phaseArray`.
+
 ```swift
 @objc func updateIcon() {
 	...