Objective-C中的NSRegularExpression

Question

NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(\\[(\\d{2}):(\\d{2})\\.(\\d{2})\\])+(.+)" options:NSRegularExpressionAllowCommentsAndWhitespace error:&error];

[regex enumerateMatchesInString:self options:NSMatchingReportProgress range:NSMakeRange(0, [self length]) usingBlock:^(NSTextCheckingResult *match, NSMatchingFlags flags, BOOL *stop){
        [*lyricObject addObject:[self substringWithRange:[match rangeAtIndex:5]]];
        NSLog(@"%@",[self substringWithRange:[match rangeAtIndex:1]]);
        [*stamp addObject:[NSString stringWithFormat:@"%d", ([[self substringWithRange:[match rangeAtIndex:2]] intValue] * 60  +  [[self substringWithRange:[match rangeAtIndex:3]] intValue] ) * 100 + [[self substringWithRange:[match rangeAtIndex:4]] intValue]]];
}];

Just like the code above the input string(self) is:

[04:30.50]There are pepole dying
[04:32.50]If you care enough for the living
[04:35.50]Make a better place for you and for me
[04:51.50][04:45.50][04:43.50][04:39.50]You and for me

and I want to get the for groups for [04:51.50][04:45.50][04:43.50][04:39.50] but I can only get the last on [04:39.50]

Is the NSRegularExpression can only get the last group when I search (($1)($2)($3)){2}

Answer 1

A repeated backreference only captures the last repetition. Your regex does match all four instances in that last line, but it overwrites each match with the next one, leaving only [04:39.50] at the end.

Solution: Repeat a non-capturing group, and put the repeated result into the capturing group:

((?:\\[(\\d{2}):(\\d{2})\\.(\\d{2})\\])+)(.+)

You still can only access $2 through $4 for the last repetition, of course - but this is a general limitation of regexes. If you need to access each match individually, down to the minutes/seconds/frames parts, then use

((?:\\[\\d{2}:\\d{2}\\.\\d{2}\\])+)(.+)

to match each line first, and then apply a second regex to $1 in iteration to extract the minutes etc.:

\\[(\\d{2}):(\\d{2})\\.(\\d{2})\\]