Fixed deprecation warning on IOS

Author: stigi

Sources/OAuth2Client/NXOAuth2PostBodyPart.m

@@ -71,7 +71,7 @@ - (id)initWithName:(NSString *)name fileContent:(NSString *)path;
     [headers appendString:@"Content-Type: application/octet-stream\r\n"];
 	[headers appendString:@"\r\n"];
 
-#if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_6
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_6 || TARGET_OS_IPHONE
 	NSDictionary *fileAttributes = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];
 #else
     NSDictionary *fileAttributes = [[NSFileManager defaultManager] fileAttributesAtPath:path traverseLink:YES];