Question

如果我有一个返回值为的字符串：

<div style="clear:both;"></div>
                <div style="float:left;">
                    <div style="float:left; height:27px; font-size:13px; padding-top:2px;">
                        <div style="float:left;"><a href="http://www.hulkshare.com/ap-nxy2n2wn7ke8.mp3" rel="nofollow" target="_blank" style="color:green;">Download</a></div>

如何从中获取<a href="http://www.hulkshare.com/ap-nxy2n2wn7ke8.mp3"部分？如果有关于此的帖子，我很抱歉，我找不到任何帖子。

Answer 1

我会看一下NSRegularExpression Class

http://developer.apple.com/library/ios/#documentation/Foundation/Reference/NSRegularExpression_Class/Reference/Reference.html

Answer 2

这是使用正则表达式查找子字符串的示例。它查找“href =”，然后查找href =之后的第一个引号（“）。一旦找到这些索引，就会返回之间的字符串。

在我的示例中并不真正需要正则表达式，您可以使用简单的NSString方法来查找子字符串。

这只是一个符合您特定情况的硬编码示例。在实践中，最好使用DOM / XML解析器来执行此类操作。

另外我假设你想要提取实际的URL并且不关心

另请注意，此函数不处理字符串中没有href匹配的情况。

- (NSString *)stringByExtractingAnchorTagURLFromString:(NSString *)dom {
    NSError *error;

    // Find the "href=" part
    NSRegularExpression *firstRegexp = [NSRegularExpression regularExpressionWithPattern:@"href=\"" options:NSRegularExpressionCaseInsensitive error:&error];
    NSTextCheckingResult *firstResult = [firstRegexp firstMatchInString:dom options:NSMatchingReportProgress range:NSMakeRange(0, [dom length])];

    NSUInteger startIndex = firstResult.range.location + firstResult.range.length;

    // Find the first quote (") character after the href=
    NSRegularExpression *secondRegexp = [NSRegularExpression regularExpressionWithPattern:@"\"" options:NSRegularExpressionCaseInsensitive error:&error];
    NSTextCheckingResult *secondResult = [secondRegexp firstMatchInString:dom options:NSMatchingReportProgress range:NSMakeRange(startIndex, [dom length]-startIndex)];

    NSUInteger endIndex = secondResult.range.location;

    // The URL is the string between these two found locations
    return [dom substringWithRange:NSMakeRange(startIndex, endIndex-startIndex)];
}

这是我测试它的方式：

NSString *dom = @"<div style=\"clear:both;\"></div><div style=\"float:left;\"><div style=\"float:left; height:27px; font-size:13px; padding-top:2px;\"><div style=\"float:left;\"><a href=\"http://www.hulkshare.com/ap-nxy2n2wn7ke8.mp3\" rel=\"nofollow\" target=\"_blank\" style=\"color:green;\">Download</a></div>";
NSString *result = [self stringByExtractingAnchorTagURLFromString:dom];
NSLog(@"Result: %@", result);

测试打印：

Result: http://www.hulkshare.com/ap-nxy2n2wn7ke8.mp3

更新 - 多个HREF

对于多个href，请使用此函数，该函数将返回包含URL的NSStrings数组：

- (NSArray *)anchorTagURLsFromString:(NSString *)dom {
    NSError *error;
    NSMutableArray *urls = [NSMutableArray array];

    // First find all matching hrefs in the dom
    NSRegularExpression *firstRegexp = [NSRegularExpression regularExpressionWithPattern:@"href=\"" options:NSRegularExpressionCaseInsensitive error:&error];
    NSArray *matches = [firstRegexp matchesInString:dom options:NSMatchingReportProgress range:NSMakeRange(0, [dom length])];

    // Go through all matches and extrac the URL
    for (NSTextCheckingResult *match in matches) {
        NSUInteger startIndex = match.range.location + match.range.length;

        // Find the first quote (") character after the href=
        NSRegularExpression *secondRegexp = [NSRegularExpression regularExpressionWithPattern:@"\"" options:NSRegularExpressionCaseInsensitive error:&error];
        NSTextCheckingResult *secondResult = [secondRegexp firstMatchInString:dom options:NSMatchingReportProgress range:NSMakeRange(startIndex, [dom length]-startIndex)];

        NSUInteger endIndex = secondResult.range.location;

        [urls addObject:[dom substringWithRange:NSMakeRange(startIndex, endIndex-startIndex)]];
    }

    return urls;
}

这是我测试它的方式：

NSString *dom2 = @"<div style=\"clear:both;\"></div><div style=\"float:left;\"><div style=\"float:left; height:27px; font-size:13px; padding-top:2px;\"><div style=\"float:left;\"><a href=\"http://www.hulkshare.com/ap-nxy2n2wn7ke8.mp3\" rel=\"nofollow\" target=\"_blank\" style=\"color:green;\">Download</a><a href=\"http://www.google.com/blabla\" rel=\"nofollow\" target=\"_blank\" style=\"color:green;\">Download</a></div>";
NSArray *urls = [self anchorTagURLsFromString:dom2];
for (NSString *url in urls) {
    NSLog(@"URL: %@", url);
}

这是测试的输出：

URL: http://www.hulkshare.com/ap-nxy2n2wn7ke8.mp3
URL: http://www.google.com/blabla

获取字符串的某些部分

2 个答案: