mineType 文件类型

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
//获取session对象
NSString *urlStr = @"http://upload.jianshu.io/collections/images/229578/1448374496.jpg?imageMogr/thumbnail/300x300";

NSURLSession *session = [NSURLSession sharedSession];

NSURL *url = [NSURL URLWithString:urlStr];

NSURLSessionTask *task = [session dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
    NSLog(@"%@",response.MIMEType);
}];
//启动任务
[task resume];
}
 输出：image/png