iOS NSMutableURLRequest 上传图片

- (void)postImage:(UIImage *)_image
{
//分界线的标识符
NSString *TWITTERFON_FORM_BOUNDARY = @"AaB03x";
//根据url初始化request
NSInteger schoolID = [[BaseUser shareInstance].userIdentity.school_id integerValue];
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:[NSString stringWithFormat:@"url"]
cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
timeoutInterval:10];
//分界线 --AaB03x
NSString *MPboundary=[[NSString alloc]initWithFormat:@"--%@",TWITTERFON_FORM_BOUNDARY];
//结束符 AaB03x--
NSString *endMPboundary=[[NSString alloc]initWithFormat:@"%@--",MPboundary];
//要上传的图片
UIImage *image= _image;
//得到图片的data
NSData* data = UIImagePNGRepresentation(image);
//http body的字符串
NSMutableString *body=[[NSMutableString alloc]init];
//参数的集合的所有key的集合
NSDictionary *param = @{};
NSArray *keys = [[param keyValues] 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",[[param keyValues] 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--AaB03x--
[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", [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 sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
if (connectionError) {

}else{
NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
NSLog(@"上传成功");
}
}];

}