[Issue #85][Issue #87] Adding useHTTPBasicAuthentication property to conditionally encode client credentials in Base64-encoded HTTP Authorization header field, rather than in body of request.

Author: mattt

AFOAuth2Manager/AFOAuth2Manager.h

@@ -49,6 +49,11 @@
  */
 @property (readonly, nonatomic, copy) NSString *clientID;
 
+/**
+ Whether to encode client credentials in a Base64-encoded HTTP `Authorization` header, as opposed to the request body. Defaults to `YES`.
+ */
+@property (nonatomic, assign) BOOL useHTTPBasicAuthentication;
+
 ///------------------------------------------------
 /// @name Creating and Initializing OAuth 2 Clients
 ///------------------------------------------------
@@ -67,7 +72,7 @@
                            secret:(NSString *)secret;
 
 /**
- Initializes an `AFOAuth2Manager` object with the specified base URL, client identifier, and secret.
+ Initializes an `AFOAuth2Manager` object with the specified base URL, client identifier, and secret. The communication to to the server will use HTTP basic auth by default (use `-(id)initWithBaseURL:clientID:secret:withBasicAuth:` to change this).
 
  @param url The base URL for the HTTP client. This argument must not be `nil`.
  @param clientID The client identifier issued by the authorization server, uniquely representing the registration information provided by the client.

AFOAuth2Manager/AFOAuth2Manager.m

@@ -85,6 +85,7 @@ @interface AFOAuth2Manager ()
 @property (readwrite, nonatomic, copy) NSString *serviceProviderIdentifier;
 @property (readwrite, nonatomic, copy) NSString *clientID;
 @property (readwrite, nonatomic, copy) NSString *secret;
+@property (readonly, nonatomic)  BOOL basicAuth;
 @end
 
 @implementation AFOAuth2Manager
@@ -101,23 +102,37 @@ - (id)initWithBaseURL:(NSURL *)url
                secret:(NSString *)secret
 {
     NSParameterAssert(clientID);
-
+    
     self = [super initWithBaseURL:url];
     if (!self) {
         return nil;
     }
-
+    
     self.serviceProviderIdentifier = [self.baseURL host];
     self.clientID = clientID;
     self.secret = secret;
 
-    [self.requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Accept"];
+    self.useHTTPBasicAuthentication = YES;
 
+    [self.requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Accept"];
+    
     return self;
 }
 
 #pragma mark -
 
+- (void)setUseHTTPBasicAuthentication:(BOOL)useHTTPBasicAuthentication {
+    _useHTTPBasicAuthentication = useHTTPBasicAuthentication;
+
+    if (self.useHTTPBasicAuthentication) {
+        [self.requestSerializer setAuthorizationHeaderFieldWithUsername:self.clientID password:self.secret];
+    } else {
+        [self.requestSerializer setValue:nil forHTTPHeaderField:@"Authorization"];
+    }
+}
+
+#pragma mark -
+
 - (AFHTTPRequestOperation *)authenticateUsingOAuthWithURLString:(NSString *)URLString
                                    username:(NSString *)username
                                    password:(NSString *)password
@@ -193,8 +208,10 @@ - (AFHTTPRequestOperation *)authenticateUsingOAuthWithURLString:(NSString *)URLS
                                     failure:(void (^)(NSError *error))failure
 {
     NSMutableDictionary *mutableParameters = [NSMutableDictionary dictionaryWithDictionary:parameters];
-    mutableParameters[@"client_id"] = self.clientID;
-    mutableParameters[@"client_secret"] = self.secret;
+    if (!self.useHTTPBasicAuthentication) {
+        mutableParameters[@"client_id"] = self.clientID;
+        mutableParameters[@"client_secret"] = self.secret;
+    }
     parameters = [NSDictionary dictionaryWithDictionary:mutableParameters];
 
     AFHTTPRequestOperation *requestOperation = [self POST:URLString parameters:parameters success:^(__unused AFHTTPRequestOperation *operation, id responseObject) {