Question

我有以下XML：

<?xml version="1.0" encoding="UTF-8" ?>
<root>
    <total_count>6640</total_count>
    <song id="5075">
        <title><![CDATA["Babysitting Blues"]]></title>
        <name><![CDATA["Babysitting Blues"]]></name>
        <artist id="1547"><![CDATA[Albert Collins]]></artist>
        <album id="2097"><![CDATA[Adventures In Babysitting]]></album>
        <albumartist id="1546"><![CDATA[Michael Kamen]]></albumartist>
        <tag id="11" count="1" ><![CDATA[Pop Rock]]></tag>
        <filename><![CDATA[/Volumes/data/My Documents/My Music/iTunes Media/Music/Michael Kamen/Adventures In Babysitting/09 _Babysitting Blues_.mp3]]></filename>
        <track>9</track>
        <time>247</time>
        <year>1988</year>
        <bitrate>128000</bitrate>
        <rate>44100</rate>
        <mode>cbr</mode>
        <mime>audio/mpeg</mime>
        <url><![CDATA[http://phirestalker.strangled.net:5555/play/index.php?ssid=faec0117bac5875e1aeb8b15f1826bdf&type=song&oid=5075&uid=3&player=api&name=Albert%20Collins%20-%20-Babysitting%20Blues-.m4a]]></url>
        <size>4119468</size>
        <mbid>4a8b4607-0f7e-4e04-8c62-a9280bb1ff1e</mbid>
        <album_mbid>e80a4221-e21c-4505-af97-27fede6100f4</album_mbid>
        <artist_mbid>5ea2c7d2-cd9c-41ba-a1c2-42889e9c4584</artist_mbid>
        <albumartist_mbid>adcc6c98-0bf1-4d54-84aa-2249cf5e46bf</albumartist_mbid>
        <art><![CDATA[http://phirestalker.strangled.net:5555/image.php?object_id=2097&object_type=album&auth=faec0117bac5875e1aeb8b15f1826bdf]]></art>
        <preciserating>0</preciserating>
        <rating>0</rating>
        <averagerating>0</averagerating>
        <composer><![CDATA[]]></composer>
        <channels></channels>
        <comment><![CDATA[00000000 00000210 00000C24 0000000000A6884C 02000003 003C6398 00000000 00000000 00000000 00000000 00000000 00000000]]></comment>
        <publisher><![CDATA[Intrada]]></publisher>
        <language>eng</language>
        <replaygain_album_gain>0.000000</replaygain_album_gain>
        <replaygain_album_peak>0.000000</replaygain_album_peak>
        <replaygain_track_gain>-0.520000</replaygain_track_gain>
        <replaygain_track_peak>0.540040</replaygain_track_peak>
        <genre><![CDATA[Pop Rock]]></genre>
    </song>
    <song>
        ...
    </song>
    ...
</root>

我正在尝试使用此代码来获取包含特定标题的所有<song>个节点（这是正确的术语吗？）。

Return = [[NSXMLDocument alloc] initWithContentsOfURL:documentsURL options:(NSXMLDocumentTidyXML) error:&err];
if(err)
{
    NSLog(@"Error parsing xml file: %@",err);
    err = nil;
}
NSArray* results = [Return nodesForXPath:@"//root/song[@title='1-2-3']" error:&err];
if(err)
{
    NSLog(@"Error searching songs: %@",err);
    err = nil;
}
NSLog(@"we got this far\n%@",results);
if(results)
{
[results enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
    NSXMLElement* node = (NSXMLElement *)obj;
    NSString *artist = [[node attributeForName:@"artist"] stringValue];
    NSString *album = [[node attributeForName:@"album"] stringValue];
    NSLog(@"artist:%@\talbum:%@",artist,album);
}];
}

问题是整个results数组是空的，所以我的XPath查询根本不起作用。我尝试了很多来源，试图拼凑如何进行查询。我甚至尝试过W3C的XPath 2.0规范，但那是WAAAAAAY太复杂了。

有谁能告诉我在查询中我做错了什么？

Answer 1

＆＃34;我正在尝试使用此代码获取包含特定标题的所有<song>个节点（这是正确的术语？）。＆＃34;

@用于引用XML属性。由于title是元素，因此您的案例的正确XPath将是：

//root/song[child::title='1-2-3']

并且由于child是XPath中的默认轴，因此可以暗示：

//root/song[title='1-2-3']

将XPath与NSXMLDocument Objective-C一起使用

1 个答案: