URLComponents is missing percentEncodedQueryItems.

stdlib/public/SDK/Foundation/URLComponents.swift

@@ -291,6 +291,15 @@ public struct URLComponents : ReferenceConvertible, Hashable, Equatable, _Mutabl
         set { _applyMutation { $0.queryItems = newValue } }
     }
 
+    /// Returns an array of query items for this `URLComponents`, in the order in which they appear in the original query string. Any percent-encoding in a query item name or value is retained
+    ///
+    /// The setter combines an array containing any number of `URLQueryItem`s, each of which represents a single key-value pair, into a query string and sets the `URLComponents` query property. This property assumes the query item names and values are already correctly percent-encoded, and that the query item names do not contain the query item delimiter characters '&' and '='. Attempting to set an incorrectly percent-encoded query item or a query item name with the query item delimiter characters '&' and '=' will cause a `fatalError`.
+    @available(macOS 10.13, iOS 11.0, tvOS 11.0, watchOS 4.0, *)
+    public var percentEncodedQueryItems: [URLQueryItem]? {
+        get { return _handle.map { $0.percentEncodedQueryItems } }
+        set { _applyMutation { $0.percentEncodedQueryItems = newValue } }
+    }
+
     public var hashValue: Int {
         return _handle.map { $0.hash }
     }

test/stdlib/TestURL.swift

@@ -178,8 +178,8 @@ class TestURL : TestURLSuper {
 
     func testURLComponents() {
         // Not meant to be a test of all URL components functionality, just some basic bridging stuff
-        let s = "http://www.apple.com/us/search/ipad?src=globalnav"
-        let components = URLComponents(string: s)!
+        let s = "http://www.apple.com/us/search/ipad?src=global%7Cnav"
+        var components = URLComponents(string: s)!
         expectNotNil(components)
 
         expectNotNil(components.host)
@@ -201,7 +201,45 @@ class TestURL : TestURLSuper {
 
             expectEqual("src", first.name)
             expectNotNil(first.value)
-            expectEqual("globalnav", first.value)
+            expectEqual("global|nav", first.value)
+        }
+
+        if #available(OSX 10.13, iOS 11.0, tvOS 11.0, watchOS 4.0, *) {
+            components.percentEncodedQuery = "name1%E2%80%A2=value1%E2%80%A2&name2%E2%80%A2=value2%E2%80%A2"
+            var qi = components.queryItems!
+            expectNotNil(qi)
+
+            expectEqual(2, qi.count)
+
+            expectEqual("name1•", qi[0].name)
+            expectNotNil(qi[0].value)
+            expectEqual("value1•", qi[0].value)
+
+            expectEqual("name2•", qi[1].name)
+            expectNotNil(qi[1].value)
+            expectEqual("value2•", qi[1].value)
+
+            qi = components.percentEncodedQueryItems!
+            expectNotNil(qi)
+
+            expectEqual(2, qi.count)
+
+            expectEqual("name1%E2%80%A2", qi[0].name)
+            expectNotNil(qi[0].value)
+            expectEqual("value1%E2%80%A2", qi[0].value)
+
+            expectEqual("name2%E2%80%A2", qi[1].name)
+            expectNotNil(qi[0].value)
+            expectEqual("value2%E2%80%A2", qi[1].value)
+
+            qi[0].name = "%E2%80%A2name1"
+            qi[0].value = "%E2%80%A2value1"
+            qi[1].name = "%E2%80%A2name2"
+            qi[1].value = "%E2%80%A2value2"
+
+            components.percentEncodedQueryItems = qi
+
+            expectEqual("%E2%80%A2name1=%E2%80%A2value1&%E2%80%A2name2=%E2%80%A2value2", components.percentEncodedQuery)
         }
     }