1  #import <Foundation/Foundation.h>
 2  
 3  NSString * const NSURLAuthenticationMethodClientCertificate = @"NSURLAuthenticationMethodClientCertificate";
 4  NSString * const NSURLAuthenticationMethodDefault = @"NSURLAuthenticationMethodDefault";
 5  NSString * const NSURLAuthenticationMethodHTMLForm = @"NSURLAuthenticationMethodHTMLForm";
 6  NSString * const NSURLAuthenticationMethodHTTPBasic = @"NSURLAuthenticationMethodDefault";
 7  NSString * const NSURLAuthenticationMethodHTTPDigest = @"NSURLAuthenticationMethodHTTPDigest";
 8  NSString * const NSURLAuthenticationMethodNTLM = @"NSURLAuthenticationMethodNTLM";
 9  NSString * const NSURLAuthenticationMethodNegotiate = @"NSURLAuthenticationMethodNegotiate";
10  // NSURLAuthenticationMethodOAuth
11  NSString * const NSURLAuthenticationMethodServerTrust = @"NSURLAuthenticationMethodServerTrust";
12  // NSURLAuthenticationMethodXMobileMeAuthToken
13  
14  NSString * const NSURLProtectionSpaceFTP = @"ftp";
15  NSString * const NSURLProtectionSpaceFTPProxy = @"ftp";
16  NSString * const NSURLProtectionSpaceHTTP = @"http";
17  NSString * const NSURLProtectionSpaceHTTPProxy = @"http";
18  NSString * const NSURLProtectionSpaceHTTPS = @"https";
19  NSString * const NSURLProtectionSpaceHTTPSProxy = @"https";
20  NSString * const NSURLProtectionSpaceSOCKSProxy = @"SOCKS";