问如何在NSString中查找某个格式的匹配项

EN

NSString *feed = @"Feed for 03/02/2012";

NSError *error;

NSRegularExpression *regex = [NSRegularExpression         
    regularExpressionWithPattern:@"([0-9]{1,2})/([0-9]{1,2})/([0-2][0-9]{3})"
    options:NSRegularExpressionCaseInsensitive
    error:&error];

[regex enumerateMatchesInString:feed options:0 range:NSMakeRange(0, [feed length])    usingBlock:^(NSTextCheckingResult *match, NSMatchingFlags flags, BOOL *stop){
    NSString *month = [feed substringWithRange:[match rangeAtIndex:1]];
    NSString *day = [feed substringWithRange:[match rangeAtIndex:2]];
    NSString *year = [feed substringWithRange:[match rangeAtIndex:3]];
    //...
}];