DOM是什么时候准备好的，如何枚举它的元素？ [英] When is the DOM ready and how to enumerate its elements?

问题描述

   - （void）webView：（WebView *）sender didFinishLoadForFrame：（WebFrame *）frame {
 DOMDocument * myDOMDocument = [[self.webview mainFrame] DOMDocument]; 
  

看起来像一个很好的起点，但是我发现WebScriptObject类引用有点神秘。显然我不想评估一些Javascript来获取链接。我想直接阅读DOM。

如何查找DOM中的哪些节点是链接，并获取他们指向的地址？

解决方案

查找图像的DOMNodes

请参阅walkNodeTree @ http://cocoadev.com/wiki/DOMCore

- 完整的示例来查找图像节点，获取他们的src和make nsimages

  @implementation DDAppDelegate 
 
  - （void）applicationDidFinishLaunching：（NSNotification *）aNotification {
 [self.webview.mainFrame loadRequest：[NSURLRequest requestWithURL：[NSURL URLWithString：@http://dominik.pich.info/Home.html]]]; 
} 
 
  - （void）webView：（WebView *）sender didFinishLoadForFrame :( WebFrame *）frame {
 DOMDocument * myDOMDocument = [[self.webview mainFrame] DOMDocument]; 
 
 NSMutableArray * imgs = [NSMutableArray数组]; 
 [self walkNodeTree：myDOMDocument imgsCollected：imgs]; 
 
 //坏代码，演示
 NSMutableArray * nsImages = [NSMutableArray数组]; （int i = 0; i< img.attributes.length; i ++）{
 DOMNode * attr = [img.attributes item：$ {
 for（DOMNode * img in imgs）一世]; 
 NSLog（@％@，attr.nodeName）; 
 if（[attr.nodeName.lowercaseString isEqualToString：@src]）{
 NSString * urlstring = [attr nodeValue]; 
 NSURL * url = [NSURL URLWithString：urlstring relativeToURL：[NSURL URLWithString：@http://dominik.pich.info/]]; 
 NSImage * nsimg = [[NSImage alloc] initWithContentsOfURL：url]; 
 if（nsimg）
 [nsImages addObject：nsimg]; 
} 
} 
} 
 
 NSLog（@％@，nsImages）; 
} 
 
  - （void）walkNodeTree：（DOMNode *）parent imgsCollected：（NSMutableArray *）imgs {
 DOMNodeList * nodeList = [parent childNodes]; 
 unsigned i，length = [nodeList length]; （i = 0; i< length; i ++）
 {
 DOMNode * node = [nodeList item：i]; 
 
 NSLog（@％@，node.nodeName）; 
 if（[node.nodeName.lowercaseString isEqualToString：@img]）{
 [imgs addObject：node]; 
} 
 else {
 // recurse 
 [self walkNodeTree：node imgsCollected：imgs]; 
} 
} 
} 
 @end 
  

Using a Webview, I would like to find the links inside this page.

-(void)webView:(WebView *)sender didFinishLoadForFrame:(WebFrame *)frame {
    DOMDocument *myDOMDocument = [[self.webview mainFrame] DOMDocument];

looks like a good starting point, but I find the WebScriptObject Class Reference a little cryptic. Clearly I don't want to evaluate some Javascript to get the links. I want to directly read the DOM.

How may I find which nodes in the DOM are links, and get the address they are pointing to ?

解决方案

Find the DOMNodes for images

see walkNodeTree @ http://cocoadev.com/wiki/DOMCore

-- complete sample to find image nodes, get their src and make nsimages

@implementation DDAppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    [self.webview.mainFrame loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://dominik.pich.info/Home.html"]]];
}

-(void)webView:(WebView *)sender didFinishLoadForFrame:(WebFrame *)frame {
    DOMDocument *myDOMDocument = [[self.webview mainFrame] DOMDocument];

    NSMutableArray *imgs = [NSMutableArray array];
    [self walkNodeTree:myDOMDocument imgsCollected:imgs];

    //bad code, demo
    NSMutableArray *nsImages = [NSMutableArray array];
    for (DOMNode *img in imgs) {
        for(int i = 0; i < img.attributes.length; i++) {
            DOMNode *attr = [img.attributes item:i];
            NSLog(@"%@", attr.nodeName);
            if([attr.nodeName.lowercaseString isEqualToString:@"src"]) {
                NSString *urlstring = [attr nodeValue];
                NSURL *url = [NSURL URLWithString:urlstring relativeToURL:[NSURL URLWithString:@"http://dominik.pich.info/"]];
                NSImage *nsimg = [[NSImage alloc] initWithContentsOfURL:url];
                if(nsimg)
                    [nsImages addObject:nsimg];
            }
        }
    }

    NSLog(@"%@", nsImages);
}

- (void)walkNodeTree:(DOMNode*)parent imgsCollected:(NSMutableArray*)imgs {
    DOMNodeList *nodeList = [parent childNodes];
    unsigned i, length = [nodeList length];
    for (i = 0; i < length; i++) {
        DOMNode *node = [nodeList item:i];

        NSLog(@"%@", node.nodeName);
        if([node.nodeName.lowercaseString isEqualToString:@"img"]) {
            [imgs addObject:node];
        }
        else {
            //recurse
            [self walkNodeTree:node imgsCollected:imgs];
        }
    }
}
@end

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