Welcome to the Treehouse Community
Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.
Looking to learn something new?
Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.
Start your free trial![](https://ecs-static.teamtreehouse.com/assets/views/marketing/shared/community-banner-white-47072046c51352fe6a69f5e691ff5700b28bb11d45197d7bdf066d9ea3f72d0c.webp)
![Raphael Varquez](https://secure.gravatar.com/avatar/f05149b7ecd27d4d8b1c18e90c56ed17?s=96&d=https%3A%2F%2Fecs-static.teamtreehouse.com%2Fassets%2Fcontent%2Fdefault_avatar-445fbbabfc8dc9188fb5967fe43322ee0c3e0dd1e10f378bf8343784af5a13eb.webp&r=pg)
Raphael Varquez
4,758 PointsCreating a Generic Type Challenge 4/5
Need help trying to make an instance method that appends a number to the end of the array.
struct Queue<Element>{
var array: [Element] = []
var isEmpty: Bool {
if array.count == 0 {
return true
} else {
return false
}
}
var count: Int {
let index = array.count
return index
}
func enqueue(_ number: Element) {
array.append(number)
}
}
1 Answer
![nickyp](https://secure.gravatar.com/avatar/2e079cf24966fb0d324e1d23e17aba5b?s=96&d=https%3A%2F%2Fecs-static.teamtreehouse.com%2Fassets%2Fcontent%2Fdefault_avatar-445fbbabfc8dc9188fb5967fe43322ee0c3e0dd1e10f378bf8343784af5a13eb.webp&r=pg)
nickyp
2,140 PointsYou have to put the keyword mutating in front of your instance method
mutating func enqueue(_ element: Element) {
array.append(element)
}