NSURLConnection的使用

一：NSURLConnection（IOS9.0已经弃用）是早期apple提供的http访问方式。以下列出了常用的几个场景：GET请求，POST请求，Response中带有json数据

对于NSURLConnection有以下注意事项：（1）sendAsynchronourequest: queue: completionHandler:函数中的queue参数表示的是“handler 这个block运行在queue中，如果queue为mainThread，那么hanlder就运行在主线程；所以在处理UI的时候需要注意这个参数”

（1）Get请求（返回文本）

  //Request
    NSMutableURLRequest *urlRequest = [NSMutableURLRequest new];
    [urlRequest setURL:[NSURL URLWithString:@"http://XXX.sinaapp.com/test/test.php?namr&id=43"]];
    [urlRequest setTimeoutInterval:10.0f];
    [urlRequest setHTTPMethod:@"GET"];
    [urlRequest setCachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData];

    NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    [NSURLConnection sendAsynchronousRequest:urlRequest
                                       queue:queue
                           completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
    　　　　//根据回复Headers，确认是是否为NSHTTPURLResponse的对象
  　　  if([response isKindOfClass:[NSHTTPURLResponse class]]){
    　　      NSHTTPURLResponse *resHttp = (NSHTTPURLResponse *)response;
      　　    NSLog(@"status = %ld",resHttp.statusCode);//200 304 401......
        　　  NSDictionary *dicHeader = resHttp.allHeaderFields;
          　　NSLog(@"headers = %@",dicHeader);
　　    }
   　　 else{
     　　     NSLog(@"not http");
    　　}
　　    if(data){
   　　       NSString *html = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
      　　    NSLog(@"%@",html);
　　    }
    }];

（2）POST请求（返回文本）

    //Request

    NSMutableURLRequest *urlRequest = [NSMutableURLRequest new];

    [urlRequest setURL:[NSURL URLWithString:@"http://XXX.sinaapp.com/test/test.php"]];
    [urlRequest setTimeoutInterval:10.0f];
    [urlRequest setHTTPMethod:@"POST"];
    [urlRequest setCachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData];
    NSString *strBody = @"p1=abc&p2=12";
    [urlRequest setHTTPBody:[strBody dataUsingEncoding:NSUTF8StringEncoding]];

    NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    [NSURLConnection
     sendAsynchronousRequest:urlRequest
     queue:queue
     completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
         //确认是http
         if([response isKindOfClass:[NSHTTPURLResponse class]]){
             NSHTTPURLResponse *resHttp = (NSHTTPURLResponse *)response;
             NSLog(@"status = %ld",resHttp.statusCode);//200 304 401......
             NSDictionary *dicHeader = resHttp.allHeaderFields;
             NSLog(@"headers = %@",dicHeader);
         }
         else{
             NSLog(@"not http");
         }
         if(data){
             NSString *html = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
             NSLog(@"%@",html);
         }
    }];

（3）Response中有Json数据

    //Request

    NSMutableURLRequest *urlRequest = [NSMutableURLRequest new];

    [urlRequest setURL:[NSURL URLWithString:@"http://XXX.sinaapp.com/test/test.php"]];
    [urlRequest setTimeoutInterval:10.0f];
    [urlRequest setHTTPMethod:@"POST"];
    [urlRequest setCachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData];
    NSString *strBody = @"p1=abc&p2=12";
    [urlRequest setHTTPBody:[strBody dataUsingEncoding:NSUTF8StringEncoding]];

    NSOperationQueue *queue = [[NSOperationQueue alloc]init];

    [NSURLConnection
     sendAsynchronousRequest:urlRequest
     queue:queue
     completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
         NSError *err2 = nil;
         id jsonObject = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&err2];

         if([jsonObject isKindOfClass:[NSDictionary class]]){
             NSLog(@"NSDictionary");
             NSDictionary *dic = jsonObject;
             NSLog(@"dic = %@",dic);
         }
         else if([jsonObject isKindOfClass:[NSArray class]]){
             NSLog(@"NSDictionary");
             NSDictionary *arr = jsonObject;
             NSLog(@"arr = %@",arr);
         }
     }];

（4）Request中带有Json格式数据