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cameron swenson
9,951 Points.contains() on an array of a struct
Running the .contians() method on an array of basic types such as Int, String, etc. is fairly straight forward:
let array = [1, 2, 3, 4]
if array.contains(4) {
print("true")
}
but what about an array of a custom type such as a struct?
struct Dude {
var dudeName: String
var dudeAge: Int
}
let steve = Dude(dudeName: "Steve", dudeAge: 24)
let arrayOfDudes = [steve , Dude(dudeName: "Josh", dudeAge: 42)]
arrayOfDudes.contains(steve) gives an error.
I found a post on a forum showing me how to do .filter() but I'm not sure that is the cleanest/best method:
struct Dude {
var dudeName: String
var dudeAge: Int
}
let steve = Dude(dudeName: "Steve", dudeAge: 24)
let arrayOfDudes = [steve , Dude(dudeName: "Josh", dudeAge: 42)]
let found = arrayOfDudes.filter{ $0.name == "Steve"}.count > 0
Following the same logic I found that .contains() would be ran the same way and "throw" the same true flag I'm looking for:
struct Dude {
var dudeName: String
var dudeAge: Int
}
let steve = Dude(dudeName: "Steve", dudeAge: 24)
let arrayOfDudes = [steve , Dude(dudeName: "Josh", dudeAge: 42)]
let found = arrayOfDudes.contains{ $0.name == "Steve"}
What are the advantages of one or the other? What does the "$0" signify? Is there a smarter way of handling this?
1 Answer
Michael Reining
10,101 PointsThe $0 is shorthand code that can be used for closures. It can be confusing at times.
There is an example here:
http://fuckingswiftblocksyntax.com/
Filter is using functional programming. There are some good references here to learn more about imperative vs. functional programming. They both have their pros and cons.
http://jamesonquave.com/blog/functional-programming-in-swift/
http://www.raywenderlich.com/82599/swift-functional-programming-tutorial
I hope that helps,
Mike
PS: Thanks to the awesome resources on Team Treehouse, I launched my first app.
Now you can practice writing Swift code directly on your iPhone :-)