demo
1.http请求，get同步异步，post同步异步
get同步

//先把中文编码
    NSString *str = @"http://apis.juhe.cn/cook/query?key=5c7bb350799fb1b79485e2c040c3289a&menu=红烧肉";
    NSCharacterSet *set = [NSCharacterSet URLQueryAllowedCharacterSet];
    NSString *result = [str stringByAddingPercentEncodingWithAllowedCharacters:set];
//处理请求
    NSURL *url = [NSURL URLWithString:result];
    NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60];
    NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
    NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];

get异步

//把中文编码代码
    NSString *str = @"http://apis.juhe.cn/cook/query?key=5c7bb350799fb1b79485e2c040c3289a&menu=红烧肉";
    NSCharacterSet *set = [NSCharacterSet URLQueryAllowedCharacterSet];
    NSString *result = [str stringByAddingPercentEncodingWithAllowedCharacters:set];
//处理请求
    NSURL *url = [NSURL URLWithString:result];
    NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
        if(data!=nil){
            NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
            
        }
        if(connectionError!=nil){
            NSLog(@"%@",[connectionError description]);
        }
        if(data==nil&&connectionError==nil){
                   NSInteger responseCode = [(NSHTTPURLResponse *)response statusCode];
                   NSString *responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
                   NSLog(@"HttpResponseCode:%ld", responseCode);
                   NSLog(@"HttpResponseBody %@",responseString);
        }
    }];

post异步

//把中文编码代码
    NSString *str = @"http://apis.juhe.cn/cook/query?key=5c7bb350799fb1b79485e2c040c3289a&menu=红烧肉";
    NSCharacterSet *set = [NSCharacterSet URLQueryAllowedCharacterSet];
    NSString *result = [str stringByAddingPercentEncodingWithAllowedCharacters:set];
//处理请求
    NSURL *url = [NSURL URLWithString:result];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
    [request setHTTPMethod:@"POST"];
    NSString *str1 = @"type=focus-c";
    NSData *data = [str1 dataUsingEncoding:NSUTF8StringEncoding];
    [request setHTTPBody:data];
    [NSURLConnection sendAsynchronousRequest:request queue:   [NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
        if(data!=nil){
            NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
            
        }
        if(connectionError!=nil){
            NSLog(@"%@",[connectionError description]);
        }
        if(data==nil&&connectionError==nil)
            NSLog(@"null data");
    }];

2.session解析
（1）.类似于NSURLConnection

NSString *a = [NSString stringWithFormat:@"page=%d",i+1];
NSString *st =@"http://apis.baidu.com/showapi_open_bus/weixin/weixin_article_list?";
NSString *str = [NSString stringWithFormat:@"%@%@",st,a];
//中文编码
NSCharacterSet *set = [NSCharacterSet URLQueryAllowedCharacterSet];
NSString *result = [str stringByAddingPercentEncodingWithAllowedCharacters:set];
//处理请求
NSURL *url = [NSURL URLWithString:result];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL: url cachePolicy: NSURLRequestUseProtocolCachePolicy timeoutInterval: 10];
[request setHTTPMethod: @"GET"];
[request addValue: @"ebdce978ac5a698d60d4048fce2d50cb" forHTTPHeaderField: @"apikey"];
NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];

}];
//发送
[task resume];

（2）.服从协议，代理方法获取数据

//协议
<NSURLSessionDataDelegate>
//data属性
@property(nonatomic,retain)NSMutableData *mutableData;
//把中文编码代码
    NSString *str = @"http://apis.juhe.cn/cook/query?key=5c7bb350799fb1b79485e2c040c3289a&menu=红烧肉";
    NSCharacterSet *set = [NSCharacterSet URLQueryAllowedCharacterSet];
    NSString *result = [str stringByAddingPercentEncodingWithAllowedCharacters:set];
//处理请求
    NSURL *url = [NSURL URLWithString:result];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
    [request setHTTPMethod:@"POST"];
    NSString *str1 = @"type=focus-c";
    NSData *data = [str1 dataUsingEncoding:NSUTF8StringEncoding];
    [request setHTTPBody:data];
//SessionConfiguration 
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
    NSURLSession *session = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:nil];
    NSURLSessionTask *task =[session dataTaskWithRequest:request];
    self.mutableData = [NSMutableData data];
    [task resume];

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data{
    [self.mutableData appendData:data];
}
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask willCacheResponse:(NSCachedURLResponse *)proposedResponse completionHandler:(void (^)(NSCachedURLResponse * _Nullable))completionHandler{
        NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:self.mutableData options:0 error:nil];

}

3.AFNetworking

    NSString *str=@"http://apis.juhe.cn/cook/query";
    NSDictionary *dic=@{@"menu":@"红烧肉",@"key":@"5c7bb350799fb1b79485e2c040c3289a"};
    NSMutableURLRequest *requrst=[[AFHTTPRequestSerializer serializer]requestWithMethod:@"GET" URLString:str parameters:dic error:nil];
    NSURLSessionConfiguration *con=[NSURLSessionConfiguration defaultSessionConfiguration];
    AFHTTPSessionManager *manager=[[AFHTTPSessionManager alloc]initWithSessionConfiguration:con];
    NSURLSessionDataTask *dataTast=[manager dataTaskWithRequest:requrst completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
        if (error) {
            NSLog(@"Error:%@",error);
        }
        else
        {
            NSDictionary *dic=responseObject;
            //NSLog(@"dic1==%@",dic1);
           // NSString *ss=[[NSString alloc]initWithData:dic1 encoding:NSUTF8StringEncoding];
        }
    }];
    [dataTast resume];