objective-c - 使用 Objective C 解析 SRT 文件

Question

文本示例:

1
00:00:00,000 --> 00:00:01,000
This is the first line

2
00:00:01,000 --> 00:00:02,000
This is the second line

3
00:00:02,000 --> 00:00:03,000
This is the last line

在 JavaScript 中，我当然会用正则表达式解析它。我只是想知道，这是在 Obj C 中执行此操作的最佳方法吗？我确信我可以想出一种方式来做到这一点，但我想以一种适当的方式来做到这一点。

我只需要知道从哪里开始，我很乐意做剩下的事情，但为了便于理解，我将以这样的方式结束(伪代码):

NSDictionary
index -> [0-9]+
start -> hh:mm:ss,mmm
end -> hh:mm:ss,mmm
text -> one of the lines of text

在这种情况下，我会将三个条目解析到我的字典中。

Answer 1

一些背景:我写了一个小应用程序并创建了一个名为 stuff.srt 的文件，其中包含驻留在包中的示例；因此，我的访问方式。

这只是一个快速而肮脏的事情，一个概念验证。请注意，它不检查结果。实际应用程序总是检查它们的结果。如您所见，工作发生在 -applicationDidFinishLaunching: 方法中(我在 Mac OS X 中工作，而不是 iOS)。

编辑:

有人指出，最初发布的代码没有正确处理多行文本。为了解决这个问题，我利用了 SRT files use CRLF as their line breaks , 并搜索此序列的两次出现。然后，根据我观察到的情况，我将文本字符串中所有出现的 CRLF 更改为空格 here .这不考虑文本每一行中的前导或尾随空格。

我将 stuff.srt 文件的内容更改为:

1
00:00:00,000 --> 00:00:01,000
This is the first line
and it has a secondary line

2
00:00:01,000 --> 00:00:02,000
This is the second line

3
00:00:02,000 --> 00:00:03,000
This is the last line
and it has a secondary line too

并且代码已修改如下(我还将所有内容都放入@autoreleasepool 指令中；在解析文件的过程中可能会生成很多 autoreleased 对象!):

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    NSString *path = [[NSBundle mainBundle] pathForResource:@"stuff" ofType:@"srt"];

    NSString *string = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:NULL];

    NSScanner *scanner = [NSScanner scannerWithString:string];

    while (![scanner isAtEnd])
    {
        @autoreleasepool
        {
            NSString *indexString;
            (void) [scanner scanUpToCharactersFromSet:[NSCharacterSet newlineCharacterSet] intoString:&indexString];

            NSString *startString;
            (void) [scanner scanUpToString:@" --> " intoString:&startString];

            // My string constant doesn't begin with spaces because scanners
            // skip spaces and newlines by default.
            (void) [scanner scanString:@"-->" intoString:NULL];

            NSString *endString;
            (void) [scanner scanUpToCharactersFromSet:[NSCharacterSet newlineCharacterSet] intoString:&endString];

            NSString *textString;
            // (void) [scanner scanUpToCharactersFromSet:[NSCharacterSet newlineCharacterSet] intoString:&textString];
            // BEGIN EDIT
            (void) [scanner scanUpToString:@"\r\n\r\n" intoString:&textString];
            textString = [textString stringByReplacingOccurrencesOfString:@"\r\n" withString:@" "];
            // Addresses trailing space added if CRLF is on a line by itself at the end of the SRT file
            textString = [textString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
            // END EDIT

            NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:
                                        indexString, @"index",
                                        startString, @"start",
                                        endString , @"end",
                                        textString , @"text",
                                        nil];

            NSLog(@"%@", dictionary);
        }
    }
}

修改后的输出如下所示:

2013-02-09 16:10:17.727 SRTFileScan[4846:303] {
    end = "00:00:01,000";
    index = 1;
    start = "00:00:00,000";
    text = "This is the first line and it has a secondary line";
}
2013-02-09 16:10:17.729 SRTFileScan[4846:303] {
    end = "00:00:02,000";
    index = 2;
    start = "00:00:01,000";
    text = "This is the second line";
}
2013-02-09 16:10:17.730 SRTFileScan[4846:303] {
    end = "00:00:03,000";
    index = 3;
    start = "00:00:02,000";
    text = "This is the last line and it has a secondary line too";
}

我今天读到的另一件事是:SRT 文件格式起源于法国，输入中看到的逗号是那里使用的小数点分隔符。