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Checking whether an element was inserted into a set
Discover page available: The Standard LibrarySwift’s Set returns a tuple every time we insert a new element, which both contains the element that was inserted, but also — and this is really useful — a Bool indicating whether the element was actually inserted or not.
A great example of using tuples as lightweight types.
// BEFORE
class FavoriteManager {
private var favoriteIDs = Set<Article.ID>()
func markArticleAsFavorite(_ article: Article) -> Outcome {
guard !favoriteIDs.contains(article.id) else {
return .failure
}
favoriteIDs.insert(article.id)
return .success
}
}
// AFTER
class FavoriteManager {
private var favoriteIDs = Set<Article.ID>()
func markArticleAsFavorite(_ article: Article) -> Outcome {
let wasInserted = favoriteIDs.insert(article.id).inserted
return wasInserted ? .success : .failure
}
}
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