#import "ViewController.h"

@interface ViewController ()<NSURLSessionDataDelegate>

@end

@implementation ViewController

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {

    NSURL *url = [NSURL URLWithString:@"https://kyfw.12306.cn/otn/"];

    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[NSOperationQueue mainQueue]];

    [[session dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {

        NSLog(@"%@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);

    }] resume];

}

- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential * _Nullable))completionHandler {

    NSLog(@"%@", challenge.protectionSpace);

    /*

    NSURLSessionAuthChallengeUseCredential = 0,            Use the specified credential, which may be nil

    NSURLSessionAuthChallengePerformDefaultHandling = 1,   Default handling for the challenge - as if this delegate were not implemented; the credential parameter is ignored.

    NSURLSessionAuthChallengeCancelAuthenticationChallenge = 2, The entire request will be canceled; the credential parameter is ignored.

    NSURLSessionAuthChallengeRejectProtectionSpace = 3,         This challenge is rejected and the next authentication protection space should be tried; the credential parameter is ignored.

    */

    NSURLCredential *credentail = [[NSURLCredential alloc] initWithTrust:challenge.protectionSpace.serverTrust];

    completionHandler(NSURLSessionAuthChallengeUseCredential, credentail);

}