////  ViewController.m//  10-掌握-MD5加密#import "ViewController.h"#import "NSString+Hash.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];        // 用户输入的还是520it    // 加密：21bfcc4c2625469d8ec6f3d710dcb0fe    // 乱序：21bfcc4c2625469d8ec6f3d710dcb0fe        NSString *text = @"520it";    NSString *md = [text md5String];        NSLog(@"%@", md);}@end

////  ViewController.m//  11-掌握-HTTPS#import "ViewController.h"@interface ViewController () <NSURLSessionTaskDelegate>@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];        NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];        NSURLSessionDataTask *task = [session dataTaskWithURL:[NSURL URLWithString:@"https://www.apple.com/"] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {        NSLog(@"%@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);    }];        [task resume];}#pragma mark - <NSURLSessionTaskDelegate>/** * challenge ： 挑战、质询 * completionHandler : 通过调用这个block，来告诉URLSession要不要接收这个证书 */- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential *))completionHandler{    // 如果不是服务器信任类型的证书，直接返回    if (![challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) return;        // void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential *)    // NSURLSessionAuthChallengeDisposition ： 如何处理这个安全证书    // NSURLCredential ：安全证书        // 根据服务器的信任信息创建证书对象//    NSURLCredential *crdential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];    // 利用这个block说明使用这个证书//    if (completionHandler) {//        completionHandler(NSURLSessionAuthChallengeUseCredential, crdential);//    }        !completionHandler ? : completionHandler(NSURLSessionAuthChallengeUseCredential, challenge.proposedCredential);}@end