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