iPhone开发技巧之数据篇（1）--- 使用正则表达式

在处理字符串的时候，常常会用到正则表达式，在iphone os上也不例外。使用 RegexKit Frameworkhttp://regexkit.sourceforge.net/RegexKitLite/index.html 就可以了。在这里http://downloads.sourceforge.net/regexkit/RegexKitLite-4.0.tar.bz2 下载RegexKitLite。
解压 RegexKitLite-4.0.tar.bz2 ：
1. RegexKitLite.h
2. RegexKitLite.m
3. RegexKitLite.html
4. examples
5. RKLMatchEnumerator.h
6. RKLMatchEnumerator.m
7. NSString-HexConversion.h
8. NSString-HexConversion.m
9. link_example.m
10. main.m

使用这里，我们只需要 RegexKitLite.h 和 RegexKitLite.m 两个文件，将其加入到你的工程中。另外加入 -licucore 链接开关。简单的例子如下：
1. NSString *searchString      = @"This is neat.";
2. NSString *regexString       = @"\\b(\\w+)\\b";
3. NSString *replaceWithString = @"{$1}";
4. NSString *replacedString    = NULL;
5.
6. replacedString = [searchString stringByReplacingOccurrencesOfRegex:regexString withString:replaceWithString];
7. NSLog(@"replaced string: '%@'", replacedString);

出结果为：
1. replaced string: '{This} {is} {neat}.'

时，也可以使用 Enumerator 来取得每个匹配的项。
1. #import <Foundation/NSAutoreleasePool.h>
2. #import "RegexKitLite.h"
3. #import "RKLMatchEnumerator.h"
4.
5. int main(int argc, char *argv[]) {
6.   NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
7.
8.   NSString     *searchString    = @"one\ntwo\n\nfour\n";
9.   NSEnumerator *matchEnumerator = NULL;
10.   NSString     *regexString     = @"(?m)^.*[        DISCUZ_CODE_3        ]quot;;
11.
12.   NSLog(@"searchString: '%@'", searchString);
13.   NSLog(@"regexString : '%@'", regexString);
14.
15.   matchEnumerator = [searchString matchEnumeratorWithRegex:regexString];
16.
17.   NSUInteger line          = 0;
18.   NSString   *matchedString = NULL;
19.
20.   while((matchedString = [matchEnumerator nextObject]) != NULL) {
21.     NSLog(@"%d: %d '%@'", ++line, [matchedString length], matchedString);
22.   }
23.
24.   [pool release];
25.   return(0);
26. }

例子解析HTML下面用一个例子，来举例匹配HTML中字符串的方法。从img-tag中抽出alt属性的值。
1. <img src="/img/icon_new_b.gif" alt="test1" width="13" height="13" />
2. <img src="/img/icon_news_b.gif" alt="test2" width="13" height="13" />

1. NSString *details = [item objectForKey:@"description"];
2. if ([details length] > 0) {
3.     NSString *searchString = [details stringByHalfwideningLatinCharacters];
4.
5.     NSEnumerator *matchEnumerator = NULL;
6.     NSString *regex = @"<img[^>]+alt=\"([^>]+)\"[^>]*>";
7.     matchEnumerator = [searchString matchEnumeratorWithRegex:regex];
8.     NSUInteger line = 0;
9.     NSString *matchedString = NULL;
10.     while((matchedString = [matchEnumerator nextObject]) != NULL) {
11.         NSString *imgTag = matchedString;
12.         NSMutableString *alt = [NSMutableString stringWithString:imgTag];
13.
14.         NSString *replaceWithString = @"$1";
15.         NSUInteger replacedCount = [alt replaceOccurrencesOfRegex:regex withString:replaceWithString];
16.         if (replacedCount) {
17.             NSString *abbr = [abbreviationMappings objectForKey:alt];
18.             if (!abbr) {
19.                 abbr = [NSString stringWithFormat:@"[%@]", alt];
20.             }
21.             searchString = [searchString stringByReplacingOccurrencesOfString:imgTag withString:abbr];
22.         }
23.         line++;
24.     }
25.     program.details = searchString;
26. }

变换字符串
1. NSString *result;
2. NSString *sample = @"Phone Num : 010-123-456-789";
3. NSString *regex = @"(\\d{3})-";
4. NSString *replace = @"$1,";
5.
6. result = [sample stringByReplacingOccurrencesOfRegex:regex withString:replace];
7. NSLog(@"replace: %@", result);

如上所示的例子，数字间的“-”被置换为“,”输出结果为：
1. replace: Phone Num : 010,123,456,789

分割字符串
1. NSString *sample = @"This is sample";
2. NSString *regex = @"\\s+";
3. NSArray *results = [sample componentsSeparatedByRegex:regex];
4. NSLog(@"results: %@", results);

结果如下：
1. results: (
2.    This,
3.    is,
4.    sample
5. )

除此之外，还有许多实用的地方，有兴趣的可以继续研究。

摘自 ioser

补充：移动开发 , IOS ,