Get&Post登录

 #import "MJViewController.h"

 @interface MJViewController ()
 @property (weak, nonatomic) IBOutlet UITextField *userName;
 @property (weak, nonatomic) IBOutlet UITextField *userPwd;

 @property (weak, nonatomic) IBOutlet UILabel *logonResult;

 @end

 @implementation MJViewController
 /**
  所有网络请求,统一使用异步请求!

  在今后的开发中,如果使用简单的get/head请求,可以用NSURLConnction异步方法
  GET查/POST增/PUT改/DELETE删/HEAD

 18  GET
 19  1> URL
 20  2> NSURLRequest
 21  3> NSURLConnction 异步
 22
 23  POST
 24  1> URL
 25  2> NSMutableURLRequest
 26     .HTTPMethod = @"POST";
 27     str 从 firebug直接粘贴,或者自己写
 28     变量名1=数值1&变量名2=数值2
 29
 30     .HTTPBody  = [str dataUsingEncoding:NSUTF8StringEncoding];
 31  3> NSURLConnction 异步

  */
 - (IBAction)userLogon
 {
     [self postLogon];
 }

 #pragma mark - POST登录
 - (void)postLogon
 {
     // 1. URL
     NSURL *url = [NSURL URLWithString:@"http://localhost/login.php"];

     // 2. 请求(可以改的请求)
     NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
     // ? POST
     // 默认就是GET请求
     request.HTTPMethod = @"POST";
     // ? 数据体
     NSString *str = [NSString stringWithFormat:@"username=%@&password=%@", self.userName.text, self.userPwd.text];
     // 将字符串转换成数据
     request.HTTPBody = [str dataUsingEncoding:NSUTF8StringEncoding];

     // 3. 连接,异步
     [NSURLConnection sendAsynchronousRequest:request queue:[[NSOperationQueue alloc] init] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {

         if (connectionError == nil) {
             // 网络请求结束之后执行!
             // 将Data转换成字符串
             NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

             // num = 2
             NSLog(@"%@ %@", str, [NSThread currentThread]);

             // 更新界面
             [[NSOperationQueue mainQueue] addOperationWithBlock:^{
                 self.logonResult.text = str;
             }];
         }
     }];

     // num = 1
     NSLog(@"come here %@", [NSThread currentThread]);
 }

 #pragma mark - GET登录
 - (void)getLogon
 {
     // 1. URL
     NSString *urlStr = [NSString stringWithFormat:@"http://localhost/login.php?username=%@&password=%@", self.userName.text, self.userPwd.text];

     NSURL *url = [NSURL URLWithString:urlStr];

     // 2. Request
     NSURLRequest *request = [NSURLRequest requestWithURL:url];

     // 3. Connection
     // 1> 登录完成之前,不能做后续工作!
     // 2> 登录进行中,可以允许用户干点别的会更好!
     // 3> 让登录操作在其他线程中进行,就不会阻塞主线程的工作
     // 4> 结论:登陆也是异步访问,中间需要阻塞住
     [NSURLConnection sendAsynchronousRequest:request queue:[[NSOperationQueue alloc] init] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {

         if (connectionError == nil) {
             // 网络请求结束之后执行!
             // 将Data转换成字符串
             NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

             // num = 2
             NSLog(@"%@ %@", str, [NSThread currentThread]);

             // 更新界面
             [[NSOperationQueue mainQueue] addOperationWithBlock:^{
                 self.logonResult.text = @"登录完成";
             }];
         }
     }];

     // num = 1
     NSLog(@"come here %@", [NSThread currentThread]);

     NSURLResponse *response = nil;
     // 1. &response真的理解了吗?
     // 2. error:为什么是NULL,而不是nil
     // NULL是C语言的 = 0
     // 在C语言中,如果将指针的地址指向0就不会有危险

     // nil是OC的,是一个空对象发送消息不会出问题
 //    [response MIMEType];
     [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:NULL];
 }

 @end