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

    //Request
    NSMutableURLRequest *urlRequest = [NSMutableURLRequest new];
    [urlRequest setURL:[NSURL URLWithString:@"http://XXXX.sinaapp.com/test/test.php"]];
    [urlRequest setTimeoutInterval:10.0f];
    [urlRequest setHTTPMethod:@"POST"];
    [urlRequest setCachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData];
    [urlRequest setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];//这句没有也没关系

    NSDictionary *dicRequest = @{@"name":@"leo",
                                 @"id":@"456"};
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dicRequest options:NSJSONWritingPrettyPrinted error:nil];
    [urlRequest setHTTPBody:jsonData];

    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);
         }

     }];

　　

服务器端的处理与返回（将request的值末尾加上_appending，然后返回）

<?php
	header('Access-Control-Allow-Origin:*');
	$json_string = $GLOBALS['HTTP_RAW_POST_DATA'];
	$obj = json_decode($json_string);
	//echo $obj->name;
	//echo $obj->id;
	$arr = array(
        "name"=>$obj->name."_appending",
        "id"=>$obj->id."_appending");
	echo json_encode($arr);

　　

(5)从服务器下载图片（启示就是普通的GET请求，只是将response中的data转为Image而已）

 //Request
    NSMutableURLRequest *urlRequest = [NSMutableURLRequest new];
    [urlRequest setURL:[NSURL URLWithString:@"https://res.wx.qq.com/mpres/htmledition/images/pic/case-detail/nfhk_l23b6fe.jpg"]];
    [urlRequest setTimeoutInterval:10.0f];
    [urlRequest setHTTPMethod:@"GET"];
    [urlRequest setCachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData];

    [NSURLConnection
     sendAsynchronousRequest:urlRequest
     queue:[NSOperationQueue mainQueue]
     completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
         UIImage *img = [UIImage imageWithData:data];
         [self.imgView setImage:img];
     }];

（6）以上所有动作都可以使用代理来做，原理上都是一样的

NSURLConnectionDataDelegate,

NSURLConnectionDelegate,

NSURLConnectionDownloadDelegate