ios - 从网页获取图片URL

Question

我正在尝试从该网站获取图像，但我遇到了困难。我所需要的只是图像的 URL，当我打印 URL 时，我得到了回复。这是 URL，我试图在中间看到主图像，http://theoldrussuanbum.vsco.co/media/555722fde555153e3e8b4591

我一直在尝试以下代码，但没有成功。

NSURL *URL = [NSURL URLWithString:_urlTextField.text];

NSURLSession *session = [NSURLSession sharedSession];
[[session dataTaskWithURL:URL completionHandler:
  ^(NSData *data, NSURLResponse *response, NSError *error) {
      NSString *contentType = nil;
      if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
          NSDictionary *headers = [(NSHTTPURLResponse *)response allHeaderFields];


          contentType = headers[@"Content-Type"];
      }
      HTMLDocument *document = [HTMLDocument documentWithData:data
                                        contentTypeHeader:contentType];

      HTMLElement *element = [document firstNodeMatchingSelector:@"img"];

      NSString *urlString = element.attributes[@"src"];

      NSLog(@"URL: %@", urlString);

  }] resume];

有人能帮忙吗？

Answer 1

可以先用正则表达式
找到正则表达式的开头:@"twitter:image\"\\s+content=\""
然后
使用正则表达式提取 URL:@"[^>]+"

您可以在 ICU 用户指南中找到有关正则表达式语法的信息:Regular Expressions .

示例代码:

NSString *urlString = @"http://theoldrussuanbum.vsco.co/media/555722fde555153e3e8b4591";
NSURL *URL = [NSURL URLWithString:urlString];

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *sessionTask;
sessionTask = [session dataTaskWithURL:URL completionHandler:
               ^(NSData *data, NSURLResponse *response, NSError *error) {

                   NSString *html = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
                   NSRange preambleRange = [html rangeOfString:@"twitter:image\"\\s+content=\"" options:NSRegularExpressionSearch];
                   if (preambleRange.location != NSNotFound) {
                       NSString *htmlOffset = [html substringFromIndex:preambleRange.location + preambleRange.length];
                       NSRange imgUrlRange = [htmlOffset rangeOfString:@"[^>]+" options:NSRegularExpressionSearch];
                       if (imgUrlRange.location != NSNotFound) {
                           NSString *imgURLString = [htmlOffset substringWithRange:imgUrlRange];
                           NSLog(@"URL: %@", imgURLString);
                       }
                   }

               }];
[sessionTask resume];

输出:

URL: http://image.vsco.co/1/548c6a64020e11517164/555722fde555153e3e8b4591/600x800/vsco_051615.jpg"

当然，生产代码必须处理此示例代码无法处理的所有错误。