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
Framework 就可以了。在这里下载RegexKitLite。
解压 RegexKitLite-4.0.tar.bz2 ：
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RegexKitLite.h
RegexKitLite.m
RegexKitLite.html
examples
RKLMatchEnumerator.h
RKLMatchEnumerator.m
NSString-HexConversion.h
NSString-HexConversion.m
link_example.m
main.m |
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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：
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NSString *searchString = @"This is neat.";
NSString *regexString = @"\\b(\\w+)\\b";
NSString *replaceWithString = @"{$1}";
NSString *replacedString = NULL;
replacedString = [searchString stringByReplacingOccurrencesOfRegex:regexString withString:replaceWithString];
NSLog(@"replaced string: ''%@''", replacedString); |
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输出结果为：
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replaced string: ''{This} {is} {neat}.'' |
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同时，也可以使用 Enumerator 来取得每个匹配的项。
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#import <Foundation/NSAutoreleasePool.h>
#import "RegexKitLite.h"
#import "RKLMatchEnumerator.h"
int main(int argc, char *argv[]) {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSString *searchString = @"one\ntwo\n\nfour\n";
NSEnumerator *matchEnumerator = NULL;
NSString *regexString = @"(?m)^.*$";
NSLog(@"searchString: ''%@''", searchString);
NSLog(@"regexString : ''%@''", regexString);
matchEnumerator = [searchString matchEnumeratorWithRegex:regexString];
NSUInteger line = 0;
NSString *matchedString = NULL;
while((matchedString = [matchEnumerator nextObject]) != NULL) {
NSLog(@"%d: %d ''%@''", ++line, [matchedString length], matchedString);
}
[pool release];
return(0);
} |
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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。
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<img src="/img/icon_new_b.gif" alt="test1" width="13" height="13" />
<img src="/img/icon_news_b.gif" alt="test2" width="13" height="13" /> |
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NSString *details = [item objectForKey:@"description"];
if ([details length] > 0) {
NSString *searchString = [details stringByHalfwideningLatinCharacters];
NSEnumerator *matchEnumerator = NULL;
NSString *regex = @"<img[^>]+alt=\"([^>]+)\"[^>]*>";
matchEnumerator = [searchString matchEnumeratorWithRegex:regex];
NSUInteger line = 0;
NSString *matchedString = NULL;
while((matchedString = [matchEnumerator nextObject]) != NULL) {
NSString *imgTag = matchedString;
NSMutableString *alt = [NSMutableString stringWithString:imgTag];
NSString *replaceWithString = @"$1";
NSUInteger replacedCount = [alt replaceOccurrencesOfRegex:regex withString:replaceWithString];
if (replacedCount) {
NSString *abbr = [abbreviationMappings objectForKey:alt];
if (!abbr) {
abbr = [NSString stringWithFormat:@"[%@]", alt];
}
searchString = [searchString stringByReplacingOccurrencesOfString:imgTag withString:abbr];
}
line++;
}
program.details = searchString;
} |
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置换字符串
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NSString *result;
NSString *sample = @"Phone Num : 010-123-456-789";
NSString *regex = @"(\\d{3})-";
NSString *replace = @"$1,";
result = [sample stringByReplacingOccurrencesOfRegex:regex withString:replace];
NSLog(@"replace: %@", result); |
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如上所示的例子，数字间的“-”被置换为“,”输出结果为：
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replace: Phone Num : 010,123,456,789 |
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分割字符串
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NSString *sample = @"This is sample";
NSString *regex = @"\\s+";
NSArray *results = [sample componentsSeparatedByRegex:regex];
NSLog(@"results: %@", results); |
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结果如下：
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results: (
This,
is,
sample
) |
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除此之外，还有许多实用的地方，有兴趣的可以继续研究。
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