NSMutableURLRequest HTTPHeaderFields are now stored case sensitive but evaluated insensitively

Author: ChrisChares

Foundation/NSURLRequest.swift

@@ -389,7 +389,13 @@ public class NSMutableURLRequest : NSURLRequest {
         if _httpHeaderFields == nil {
             _httpHeaderFields = [:]
         }
-        _httpHeaderFields?[field.lowercaseString] = value
+        if let existingHeader = _httpHeaderFields?.filter({ (existingField, _) -> Bool in
+            return existingField.lowercaseString == field.lowercaseString
+        }).first {
+            let (existingField, _) = existingHeader
+            _httpHeaderFields?.removeValueForKey(existingField)
+        }
+        _httpHeaderFields?[field] = value
     }
 
     /*! 
@@ -410,10 +416,13 @@ public class NSMutableURLRequest : NSURLRequest {
         if _httpHeaderFields == nil {
             _httpHeaderFields = [:]
         }
-        if let oldValue = _httpHeaderFields?[field.lowercaseString] {
-            _httpHeaderFields?[field.lowercaseString] = "\(oldValue),\(value)"
+        if let existingHeader = _httpHeaderFields?.filter({ (existingField, _) -> Bool in
+            return existingField.lowercaseString == field.lowercaseString
+        }).first {
+            let (existingField, existingValue) = existingHeader
+            _httpHeaderFields?[existingField] = "\(existingValue),\(value)"
         } else {
-            _httpHeaderFields?[field.lowercaseString] = value
+            _httpHeaderFields?[field] = value
         }
     }
 }

TestFoundation/TestNSURLRequest.swift

@@ -41,6 +41,7 @@ class TestNSURLRequest : XCTestCase {
     func test_mutableConstruction() {
         let URL = NSURL(string: "http://swift.org")!
         let request = NSMutableURLRequest(URL: URL)
+        
         //Confirm initial state matches NSURLRequest responses
         XCTAssertNotNil(request)
         XCTAssertEqual(request.URL, URL)
@@ -61,11 +62,18 @@ class TestNSURLRequest : XCTestCase {
 
     func test_headerFields() {
         let request = NSMutableURLRequest(URL: URL)
-        request.setValue("application/json", forHTTPHeaderField: "accept")
+        
+        request.setValue("application/json", forHTTPHeaderField: "Accept")
         XCTAssertNotNil(request.allHTTPHeaderFields)
-        XCTAssertEqual(request.allHTTPHeaderFields?["accept"], "application/json")
-        //HTTP Header fields should be case insensitive
+        XCTAssertEqual(request.allHTTPHeaderFields?["Accept"], "application/json")
+
+        // Setting "accept" should remove "Accept"
+        request.setValue("application/xml", forHTTPHeaderField: "accept")
+        XCTAssertNil(request.allHTTPHeaderFields?["Accept"])
+        XCTAssertEqual(request.allHTTPHeaderFields?["accept"], "application/xml")
+        
+        // Adding to "Accept" should add to "accept"
         request.addValue("text/html", forHTTPHeaderField: "Accept")
-        XCTAssertEqual(request.allHTTPHeaderFields?["accept"], "application/json,text/html")
+        XCTAssertEqual(request.allHTTPHeaderFields?["accept"], "application/xml,text/html")
     }
 }