ios开发网络篇—Get请求和Post请求

简单说明：建议提交用户的隐私数据一定要使用Post请求 
相对Post请求而言，Get请求的所有参数都直接暴露在URL中，请求的URL一般会记录在服务器的访问日志中，而服务器的访问日志是黑客攻击的重点对象之一 
用户的隐私数据如登录密码，银行帐号等

示例代码

#define CURRENT_SCREEN_WIDTH     [UIScreen mainScreen].bounds.size.width
#define CURRENT_SCREEN_HEIGHT     ([UIScreen mainScreen].bounds.size.height - 64)
#define BUTTON_WIDTH     80
#define BUTTON_HEIGHT    40

@interface ViewController ()
//GET 请求
@property(nonatomic,strong) UIButton *getButton;
//POST 请求
@property(nonatomic,strong) UIButton *postButton;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    _getButton = [[UIButton alloc] initWithFrame:CGRectMake(CURRENT_SCREEN_WIDTH/2 - BUTTON_WIDTH/2,
                                                             CURRENT_SCREEN_HEIGHT/2 - BUTTON_HEIGHT,
                                                             BUTTON_WIDTH,
                                                             BUTTON_HEIGHT)];
    [_getButton setTitle:@"GET 请求" forState:UIControlStateNormal];
    [_getButton setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [_getButton addTarget:self
                    action:@selector(getClick)
          forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:_getButton];
    
    _postButton = [[UIButton alloc] initWithFrame:CGRectMake(CURRENT_SCREEN_WIDTH/2 - BUTTON_WIDTH/2,
                                                             _getButton.frame.origin.y + _getButton.frame.size.height + 60,
                                                             BUTTON_WIDTH,
                                                             BUTTON_HEIGHT)];
    [_postButton setTitle:@"POST 请求" forState:UIControlStateNormal];
    [_postButton setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [_postButton addTarget:self
                    action:@selector(postClick)
          forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:_postButton];
}

/* get 请求 */
-(void)getClick{
    //请求 URL
    NSString* urlStr = [NSString stringWithFormat:@"https://m.che168.com/beijing/?pvareaid=%d",110100];
    //封装成 NSURL
    NSURL* url = [NSURL URLWithString:urlStr];

    //初始化 请求对象
    NSURLRequest* request = [[NSURLRequest alloc] initWithURL:url];
    //也可以这样初始化对象
    //NSURLRequest* request = [NSURLRequest requestWithURL:url];
    
    //发送请求  默认为 GET 请求
    //1 、获得会话对象
    NSURLSession *session = [NSURLSession sharedSession];
    // 2、第一个参数：请求对象
    //      第二个参数：completionHandler回调（请求完成【成功|失败】的回调）
    //      data：响应体信息（期望的数据）
    //      response：响应头信息，主要是对服务器端的描述
    //      error：错误信息，如果请求失败，则error有值
    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        if(!error){
            NSLog(@"请求加载成功。。。");
            //说明：（此处返回的数据是JSON格式的，因此使用NSJSONSerialization进行反序列化处理）
            // NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
            //如果是字符串则直接取出
            NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
            NSLog(@"GET 请求返回的结果是：%@",[str substringToIndex: 300]);
        }
    }];
    //执行任务
    [dataTask resume];
    
    /* ------------ ios9 之前请求方法，之后改成 NSURLSession 请求  --------------
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
        if(!connectionError){
            NSLog(@"加载成功。。。");
            NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
            NSLog(@"加载的内容是：%@",[str substringToIndex:200]);
        }else{
            NSLog(@"加载失败");
        }
    }];
    */
}


/* POST 请求 */
-(void)postClick{
    NSString *urlStr = [NSString stringWithFormat:@"https://m.che168.com/"];
    //转码
    // stringByAddingPercentEscapesUsingEncoding 只对 `#%^{}[]|"<> 加空格共14个字符编码，不包括”&?”等符号), ios9将淘汰
    // ios9 以后要换成 stringByAddingPercentEncodingWithAllowedCharacters 这个方法进行转码
    urlStr = [urlStr stringByAddingPercentEncodingWithAllowedCharacters:[[NSCharacterSet characterSetWithCharactersInString:@"?!@#$^&%*+,:;='"`<>()[]{}/\| "] invertedSet]];
    NSURL *url = [NSURL URLWithString:urlStr];
    
    //创建会话对象
    NSURLSession *session = [NSURLSession sharedSession];
    
    //创建请求对象
    NSMutableURLRequest *request =[[NSMutableURLRequest alloc] initWithURL:url];
    [request setHTTPMethod:@"POST"];
    [request setHTTPBody:[@"a=1&b=2&c=3&type=json" dataUsingEncoding:NSUTF8StringEncoding]];
    
    //根据会话对象创建一个 Task（发送请求）
    NSURLSessionDataTask* dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        if(!error){
            //8.解析数据
            // NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
            // NSLog(@"%@",dict);
            NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
            NSLog(@"POST 加载的内容是：%@",[str substringToIndex:200]);
        }else{
            NSLog(@"请求发生错误：%@", [error description]);
        }
    }];
    [dataTask resume]; //执行任务
}