IOS使用NSURLConnection实现文件上传

//字典里面装的是你要上传的内容
NSDictionary *parameters = @{@"content": @"此为内容"};

NSString *strURL = [NSString stringWithFormat:@"%@/Upload.php",SERVER_HOST];
//分界线的标识符
NSString *TWITTERFON_FORM_BOUNDARY = @"---------------------------JHMLY622510";

//根据url初始化request
NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:strURL]
cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
timeoutInterval:10];

//分界线
NSString *MPboundary=[[NSString alloc]initWithFormat:@"--%@",TWITTERFON_FORM_BOUNDARY];

//结束符
NSString *endMPboundary=[[NSString alloc]initWithFormat:@"%@--",MPboundary];
//	//要上传的图片
//	UIImage *image=[params objectForKey:@"pic"];
//得到图片的data
NSData *data = UIImagePNGRepresentation(nil);
//http body的字符串
NSMutableString *body=[[NSMutableString alloc]init];
//参数的集合的所有key的集合
NSArray *keys= [parameters allKeys];
//遍历keys
for(int i=0;i<[keys count];i++)
{
//得到当前key
NSString *key=[keys objectAtIndex:i];
//如果key不是pic，说明value是字符类型，比如name：Boris
if(![key isEqualToString:@"pic"])
{
//添加分界线，换行
[body appendFormat:@"%@\r\n",MPboundary];
//添加字段名称，换2行
[body appendFormat:@"Content-Disposition: form-data; name=\"%@\"\r\n\r\n",key];
//添加字段的值
[body appendFormat:@"%@\r\n",[parameters objectForKey:key]];
}
}

////添加分界线，换行
[body appendFormat:@"%@\r\n",MPboundary];
//声明pic字段，文件名为boris.png
[body appendFormat:@"Content-Disposition: form-data; name=\"pic\"; filename=\"boris.png\"\r\n"];
//声明上传文件的格式
[body appendFormat:@"Content-Type: image/png\r\n\r\n"];
//声明结束符：--AaB03x--
NSString *end=[[NSString alloc]initWithFormat:@"\r\n%@",endMPboundary];
//声明myRequestData，用来放入http body
NSMutableData *myRequestData=[NSMutableData data];
//将body字符串转化为UTF8格式的二进制
[myRequestData appendData:[body dataUsingEncoding:NSUTF8StringEncoding]];
//将image的data加入
[myRequestData appendData:data];
//加入结束符--
[myRequestData appendData:[end dataUsingEncoding:NSUTF8StringEncoding]];
//设置HTTPHeader中Content-Type的值
NSString *content=[[NSString alloc]initWithFormat:@"multipart/form-data; boundary=%@",TWITTERFON_FORM_BOUNDARY];
//设置HTTPHeader
[request setValue:content forHTTPHeaderField:@"Content-Type"];
//设置Content-Length
[request setValue:[NSString stringWithFormat:@"%d", (int)[myRequestData length]] forHTTPHeaderField:@"Content-Length"];
//设置http body
[request setHTTPBody:myRequestData];
//http method
[request setHTTPMethod:@"POST"];
//建立连接，设置代理
NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self];
//设置接受response的data
if (conn) {

}