准备工作，下载RegexKitLite 软件包，解压后有2个文件，需要加载到project中。

然后还要加载framework libicucore.dylib ，因为RegexKitLite是调用这个里面的API,苹果规定过不能使用私有的api和没有发布的api。实际上RegexKitLite对NSString做了扩展，目前只支持NSString，对我来说也够了…

基本使用的例子（更多信息参看 官方文档 ）

1.

NSString *searchString = @"This is neat.";  
NSString *regexString  = @"(//w+)//s+(//w+)//s+(//w+)";  
NSRange   matchedRange = NSMakeRange(NSNotFound, 0UL);  
NSError  *error        = NULL;  
matchedRange = [searchString rangeOfRegex:regexString options:RKLNoOptions inRange:searchRange capture:2L error:&error];  
NSLog(@"matchedRange: %@", NSStringFromRange(matchedRange));  
// 2008-03-18 03:51:16.530 test[51583:813] matchedRange: {5, 2}，//匹配到‘is‘  
NSString *matchedString = [searchString substringWithRange:matchedRange];  
NSLog(@"matchedString: '%@'", matchedString);  
// 2008-03-18 03:51:16.532 test[51583:813] matchedString: 'is' //生成子字符串  

2.找到第一个匹配并返回一个NSString

NSString *searchString  = @"This is neat.";  
NSString *regexString   = @"(//w+)//s+(//w+)//s+(//w+)";  
NSString *matchedString = [searchString stringByMatching:regexString capture:2L];  
NSLog(@"matchedString: '%@'", matchedString);  
// 2008-03-18 03:53:42.949 test[51583:813] matchedString: 'is'  

3.查找和替换，加括号和概念和Python中的一样，$1指代第一个括号中的内容

NSString *searchString      = @"This is neat.";  
NSString *regexString       = @"//b(//w+)//b";  
NSString *replaceWithString = @"{$1}";  
NSString *replacedString    = NULL;  
replacedString = [searchString stringByReplacingOccurrencesOfRegex:regexString withString:replaceWithString];  
//NSMutableString可以直接替换，并返回替换的次数  
NSLog(@"replaced string: '%@'", replacedString);  
// 2008-07-01 19:03:03.195 test[68775:813] replaced string: '{This} {is} {neat}.'  
NSMutableString *mutableString     = [NSMutableString stringWithString:@"This is neat."];  
NSString        *regexString       = @"//b(//w+)//b";  
NSString        *replaceWithString = @"{$1}";  
NSUInteger       replacedCount     = 0UL;  
replacedCount = [mutableString replaceOccurrencesOfRegex:regexString withString:replaceWithString];  
NSLog(@"count: %lu string: '%@'", (u_long)replacedCount, mutableString);  
// 2008-07-01 21:25:43.433 test[69689:813] count: 3 string: '{This} {is} {neat}.'  

4.用于拆分，返回一个拆分后的字符串数组

NSString *searchString = @"This is neat.";  
NSString *regexString  = @"//s+";  
NSArray  *splitArray   = NULL;  
splitArray = [searchString componentsSeparatedByRegex:regexString];  
// splitArray == { @"This", @"is", @"neat." }  
NSLog(@"splitArray: %@", splitArray);  

5.返回所有匹配的字符串数组，这个例子中虽然有多个括号，但是 componentsMatchedByRegex不管

NSString *searchString = @"$10.23, $1024.42, $3099";  
NSString *regexString  = @"//$((//d+)(?://.(//d+)|//.?))";  
NSArray  *matchArray   = NULL;  
matchArray = [searchString componentsMatchedByRegex:regexString];  
// matchArray == { @"$10.23", @"$1024.42", @"$3099" };  
NSLog(@"matchArray: %@", matchArray);  
6.返回所有匹配的字符串数组处理所有的括号  
NSString *searchString  = @"$10.23, $1024.42, $3099";  
NSString *regexString   = @"//$((//d+)(?://.(//d+)|//.?))";  
NSArray  *capturesArray = NULL;  
capturesArray = [searchString arrayOfCaptureComponentsMatchedByRegex:regexString];  
/* capturesArray == 
[NSArray arrayWithObjects: 
 [NSArray arrayWithObjects:  @"$10.23",   @"10.23",   @"10", @"23", NULL], 
 [NSArray arrayWithObjects:@"$1024.42", @"1024.42", @"1024", @"42", NULL], 
 [NSArray arrayWithObjects:   @"$3099",    @"3099", @"3099",   @"", NULL], 
 NULL]; 
*/  
NSLog(@"capturesArray: %@", capturesArray);  
输出结果：  
shell% ./capturesArray↵  
2009-05-06 03:25:46.852 capturesArray[69981:10b] capturesArray: (  
       (  
       "$10.23",  
       "10.23",  
       10,  
       23  
   ),  
       (  
       "$1024.42",  
       "1024.42",  
       1024,  
       42  
   ),  
       (  
       "$3099",  
       3099,  
       3099,  
       ""  
   )  
)