分享三个正则表达式：话题、URL、表情

（1）#话题#

+ (NSRegularExpression *)regexTopic {

       staticNSRegularExpression *regex;

       staticdispatch_once_t onceToken;

       dispatch_once(&onceToken, ^{

           // #[^#]+#  // #[^@#]+?# 话题

            regex = [NSRegularExpression regularExpressionWithPattern:@"#([^@]+?)#"options:kNilOptions error:NULL];

        });

       returnregex;

    }

（2）URL

#define TTRegexHttp    @"([hH]ttp[s]{0,1})://[a-zA-Z0-9\\.\\-]+\\.([a-zA-Z]{2,4})(:\\d+)?(/[a-zA-Z0-9\\-~!@#$%^&*+?:_/=<>.',;]*)?"

+ (NSRegularExpression *)regexURL {

       staticNSRegularExpression *regex;

       staticdispatch_once_t onceToken;

       dispatch_once(&onceToken, ^{

            regex = [NSRegularExpression regularExpressionWithPattern:TTRegexHttp options:kNilOptions error:NULL];

        });

       returnregex;

    }

（3）表情

 + (NSRegularExpression *)regexEmoticon {

       staticNSRegularExpression *regex;

       staticdispatch_once_t onceToken;

       dispatch_once(&onceToken, ^{

            regex = [NSRegularExpression regularExpressionWithPattern:@"\\[/[^ \\[\\]]+?\\]"options:kNilOptions error:NULL];

        });

       returnregex;

    }