网络：NSURLSession 使用 HTTPS

#import "ViewController.h"@interface ViewController ()<NSURLSessionDelegate,NSURLSessionDataDelegate>@property (nonatomic, strong) NSURLSession *session;// 自定义会话@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.}- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {    NSURL *url = [NSURL URLWithString:@"https://mail.itcast.cn"];    [[self.session dataTaskWithURL:url] resume];}//    NSURLSessionAuthChallengeUseCredential = 0, 使用（信任）证书//    NSURLSessionAuthChallengePerformDefaultHandling = 1, 默认，忽略//    NSURLSessionAuthChallengeCancelAuthenticationChallenge = 2,   取消//    NSURLSessionAuthChallengeRejectProtectionSpace = 3,      这次取消，下载次还来问// 工作中直接复制这一段代理Ok了// 金融公司- (void)URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential * __nullable credential))completionHandler {    NSLog(@"%@",challenge.protectionSpace);    // 如果是请求证书信任，我们再来处理，其他的不需要处理    if (challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust) {        NSURLCredential *cre = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];        // 调用block        completionHandler(NSURLSessionAuthChallengeUseCredential,cre);    }}- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {    NSLog(@"%@",[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]);}//- (void)demo:(void(^)())block {//    block();//}- (NSURLSession *)session {    if (_session == nil) {        _session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:nil];    }    return _session;}@end