NSURLSession实践（结合POST和GET请求JSON和XML数据）

GET方法解析JSON数据，使用NSJSONSerialization

    NSString *appkey = @"bf1d95bd730f031fb019ba80ffabb89d";
    NSString *baseURL = @"http://op.juhe.cn/onebox/weather/query";
    NSString *url = [baseURL stringByAppendingString:[NSString stringWithFormat:@"?cityname=%@&dtype=&key=%@", @"上海", appkey]];
    NSString *urlStr = [url stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:urlStr]];
    request.HTTPMethod =@"GET";
    request.timeoutInterval = 20;
    request.cachePolicy = NSURLRequestReturnCacheDataElseLoad;
    
    NSURLSession *session = [NSURLSession sharedSession];
    NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
        NSLog(@"%@", [dict allKeys]);
    }];
    [task resume];

POST方法解析JSON数据，使用NSJSONSerialization，其他参数和之前一样

    //设置请求体
    NSString *bodyStr = [NSString stringWithFormat:@"cityname=%@&dtype=&key=%@", @"上海", appkey];
    NSString *body = [bodyStr stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:baseURL]];
    request.HTTPBody = [body dataUsingEncoding:NSUTF8StringEncoding];
    request.HTTPMethod =@"POST";
    request.timeoutInterval = 20;
    request.cachePolicy = NSURLRequestReturnCacheDataElseLoad;
    
    NSURLSession *session = [NSURLSession sharedSession];
    NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
        NSLog(@"%@", [dict allKeys]);
    }];
    [task resume];