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 *)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