Array+Unique.swift

extension Array {
	func unique(predicate: (Element, Element) -> Bool) -> [Element] {
		var result: [Element] = []
		forEach { e -> Void in
			guard !result.contains({ r -> Bool in
				return predicate(r, e)
			}) else { return }
			result.append(e)
		}
		return result
	}
}

//Usage
/*
class Post {
    let id: Int
    let text: String
    
    init(id: Int, text: String) {
        self.id = id
        self.text = text
    }
}

let posts = (0...100).flatMap { Post(id: $0, text: "text\($0)") } + (20...50).flatMap { Post(id: $0, text: "text\($0)") } //132 items
let uniquePosts = posts.unique { $0.id == $1.id } //101 items
 */

the syntax not updated to the current swift version