iOS NSURLSession实现网络请求

发送POST请求 NSURL *url = [NSURL URLWithString:@”http://127.0.0.1/demo.json”]; NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; request.HTTPMethod = @”post”; NSString *body = @”username=123&password=123′′; request.HTTPBody = [body dataUsingEncoding:NSUTF8String