Array Extensions like unique, categorise

Author: piotrbernad

ArrayExtensions.swift

@@ -0,0 +1,16 @@
+public extension Sequence where Iterator.Element: Hashable {
+    func unique() -> [Iterator.Element] {
+        return Array(Set(self))
+    }
+}
+
+public extension Sequence {
+    func categorise<U : Hashable>(_ key: (Iterator.Element) -> U) -> [U:[Iterator.Element]] {
+        var dict: [U:[Iterator.Element]] = [:]
+        for el in self {
+            let key = key(el)
+            if case nil = dict[key]?.append(el) { dict[key] = [el] }
+        }
+        return dict
+    }
+}