This article describes how word and paragraph boundaries are defined, how line breaks are represented, and how you can separate a string by paragraph.
- 本文介紹如何定義單詞和段落邊界书蚪，如何表示換行符庶诡，以及如何按段落分隔字符串。
Word Boundaries
The text system determines word boundaries in a language-specific manner according to Unicode Standard Annex #29 with additional customization for locale as described in that document. On OS X, Cocoa presents APIs related to word boundaries, such as the NSAttributedString methods doubleClickAtIndex: and nextWordFromIndex:forward:, but you cannot modify the way the word-boundary algorithms themselves work.
- 文本系統(tǒng)根據(jù)Unicode標(biāo)準(zhǔn)附件＃29以特定語言的方式確定字邊界，并對(duì)該文檔中描述的區(qū)域設(shè)置進(jìn)行額外定制朝刊。 在OS X上，Cocoa提供了與字邊界相關(guān)的API，例如NSAttributedString方法doubleClickAtIndex：和nextWordFromIndex：forward：，但是您無法修改字邊界算法本身的工作方式坯门。
Line and Paragraph Separator Characters
- 線和段落分隔符
There are a number of ways in which a line or paragraph break can be represented. Historically, \n, \r, and \r\n have been used. Unicode defines an unambiguous paragraph separator, U+2029 (for which Cocoa provides the constant NSParagraphSeparatorCharacter), and an unambiguous line separator, U+2028 (for which Cocoa provides the constant NSLineSeparatorCharacter).
- 可以通過多種方式表示行或段落。 從歷史上看逗扒，已使用\ n古戴，\ r和\ r \ n。 Unicode定義了一個(gè)明確的段落分隔符矩肩，U + 2029（Cocoa為其提供常量NSParagraphSeparatorCharacter）现恼，以及一個(gè)明確的行分隔符U + 2028（Cocoa為其提供常量NSLineSeparatorCharacter）。
- 在Cocoa文本系統(tǒng)中黍檩，NSParagraphSeparatorCharacter被一致地視為段落述暂，并且NSLineSeparatorCharacter被一致地視為不是段落中斷的換行符，即段落中的換行符建炫。 但是，在其他情況下疼蛾，幾乎不能保證如何處理這些字符肛跌。 例如，POSIX級(jí)軟件通常只識(shí)別\ n作為中斷察郁。 某些較舊的Macintosh軟件僅識(shí)別\ r \ n衍慎，某些Windows軟件僅識(shí)別\ r \ n。 通常皮钠，行和段落之間沒有區(qū)別稳捆。
In the Cocoa text system, the NSParagraphSeparatorCharacter is treated consistently as a paragraph break, and NSLineSeparatorCharacter is treated consistently as a line break that is not a paragraph break—that is, a line break within a paragraph. However, in other contexts, there are few guarantees as to how these characters will be treated. POSIX-level software, for example, often recognizes only \n as a break. Some older Macintosh software recognizes only \r, and some Windows software recognizes only \r\n. Often there is no distinction between line and paragraph breaks.
- 在Cocoa文本系統(tǒng)中，NSParagraphSeparatorCharacter被一致地視為段落麦轰，并且NSLineSeparatorCharacter被一致地視為不是段落中斷的換行符乔夯，即段落中的換行符。 但是款侵，在其他情況下末荐，幾乎不能保證如何處理這些字符。 例如新锈，POSIX級(jí)軟件通常只識(shí)別\ n作為中斷甲脏。 某些較舊的Macintosh軟件僅識(shí)別\ r \ n，某些Windows軟件僅識(shí)別\ r \ n。 通常块请，行和段落之間沒有區(qū)別娜氏。
Which line or paragraph break character you should use depends on how your data may be used and on what platforms. The Cocoa text system recognizes \n, \r, or \r\n all as paragraph breaks—equivalent to NSParagraphSeparatorCharacter. When it inserts paragraph breaks, for example with insertNewline:, it uses \n. Ordinarily NSLineSeparatorCharacter is used only for breaks that are specifically line breaks and not paragraph breaks, for example in insertLineBreak:, or for representing HTML <br> elements.
- 您應(yīng)該使用哪個(gè)行或段落中斷字符取決于您的數(shù)據(jù)的使用方式以及在哪些平臺(tái)上。 Cocoa文本系統(tǒng)將\ n墩新，\ n或\ r \ n全部識(shí)別為段落符號(hào) - 相當(dāng)于NSParagraphSeparatorCharacter贸弥。 當(dāng)它插入段落符號(hào)時(shí)，例如insertNewline：抖棘，它使用\ n茂腥。 通常，NSLineSeparatorCharacter僅用于特定換行符而不是段落符的斷點(diǎn)切省，例如在insertLineBreak：中最岗，或用于表示HTML
元素。
If your breaks are specifically intended as line breaks and not paragraph breaks, then you should typically use NSLineSeparatorCharacter. Otherwise, you may use \n, \r, or \r\n depending on what other software is likely to process your text. The default choice for Cocoa is usually \n.
- 如果您的休息時(shí)間是專門用作換行符而不是分段符朝捆，那么您通常應(yīng)該使用NSLineSeparatorCharacter般渡。 否則，您可以使用\ n芙盘，\ r或\ r \ n取決于其他軟件可能處理您的文本驯用。 Cocoa的默認(rèn)選擇通常是\ n。
Separating a String “by Paragraph”
- 按段落分隔字符串
A common approach to separating a string “by paragraph” is simply to use:
- “按段落”分隔字符串的常用方法是使用：
NSArray *arr = [myString componentsSeparatedByString:@"\n"];
This, however, ignores the fact that there are a number of other ways in which a paragraph or line break may be represented in a string—\r, \r\n, or Unicode separators.
- 但是儒老，這忽略了一個(gè)事實(shí)蝴乔，即在字符串 - “\ r \ n”，“\ r \ n”或Unicode分隔符中可以表示段落或換行符驮樊。
Instead you can use methods—such as enumerateSubstringsInRange:options:usingBlock: and enumerateLinesUsingBlock:—that take into account the variety of possible line terminations, as illustrated in the following example.
- 相反薇正，您可以使用諸如enumerateSubstringsInRange：options：usingBlock：和enumerateLinesUsingBlock之類的方法： - 它考慮了各種可能的行終止，如以下示例所示囚衔。
NSString *string = /* assume this exists */;
NSRange range = NSMakeRange(0, string.length);
[string enumerateSubstringsInRange:range
options:NSStringEnumerationByParagraphs
usingBlock:^(NSString * _Nullable paragraph, NSRange paragraphRange, NSRange enclosingRange, BOOL * _Nonnull stop) { // ... }];
