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根据文本语言自动对齐UILabel中的文本

objective-cios6localizationalignmentright-to-left
7

我想将一些文本设置到UILabel中，并根据语言的方向性（例如，希伯来语-从右到左[RTL]，英语-从左到右[LTR]）设置UILabel的对齐方式。

请注意，使用iOS 6的NSTextAlignmentNatural并不能解决问题，因为它根据当前环境选择对齐方式，实验证明。

6个回答
12

最终按照此SO答案的建议：编写一个简短的脚本，解析此处公开的Unicode数据并生成代码以确定字符码点是否具有强R或AL方向属性。然后，在字符串中搜索第一个这样的字符。 这正是ICU软件包中的ubidi_getBaseDirection所做的。

由于NSString的内部表示为UTF16（可变长度编码），因此首先将其转换为UTF32以简化扫描代码。另一种方法是即时解码字符串，这需要处理BOM和Unicode代理项。还有一种方法是简单地忽略不能用一个unichar表示的字符。有关更多详细信息，请参见维基百科的UTF16文章。

简短回答

@interface NSString (TextDirectionality)

/* Return 1 if the string is strongly LTR, -1 if strongly RTL, or 0 if neutral. */
/* See http://icu-project.org/apiref/icu4c/ubidi_8h.html#aeb1fd15743833278cc11906cd5a48aef */
-(int)getBaseDirection;

@end

@implementation NSString (TextDirectionality)

// Function takes UTF32 character, and not a unichar (=UTF16 character),
// because some Unicode characters need full 32 bits to represent.
BOOL isCodePointStrongRTL(UTF32Char c) {
  return ((c == 0x5BE) || (c == 0x5C0) || (c == 0x5C3) || (c == 0x5C6) || (c >= 0x5D0 && c <= 0x5EA) || (c >= 0x5F0 && c <= 0x5F4) || (c == 0x608) || (c == 0x60B) || (c == 0x60D) || (c == 0x61B) || (c >= 0x61E && c <= 0x64A) || (c >= 0x66D && c <= 0x66F) || (c >= 0x671 && c <= 0x6D5) || (c >= 0x6E5 && c <= 0x6E6) || (c >= 0x6EE && c <= 0x6EF) || (c >= 0x6FA && c <= 0x70D) || (c >= 0x70F && c <= 0x710) || (c >= 0x712 && c <= 0x72F) || (c >= 0x74D && c <= 0x7A5) || (c == 0x7B1) || (c >= 0x7C0 && c <= 0x7EA) || (c >= 0x7F4 && c <= 0x7F5) || (c == 0x7FA) || (c >= 0x800 && c <= 0x815) || (c == 0x81A) || (c == 0x824) || (c == 0x828) || (c >= 0x830 && c <= 0x83E) || (c >= 0x840 && c <= 0x858) || (c == 0x85E) || (c == 0x8A0) || (c >= 0x8A2 && c <= 0x8AC) || (c == 0x200F) || (c == 0xFB1D) || (c >= 0xFB1F && c <= 0xFB28) || (c >= 0xFB2A && c <= 0xFB36) || (c >= 0xFB38 && c <= 0xFB3C) || (c == 0xFB3E) || (c >= 0xFB40 && c <= 0xFB41) || (c >= 0xFB43 && c <= 0xFB44) || (c >= 0xFB46 && c <= 0xFBC1) || (c >= 0xFBD3 && c <= 0xFD3D) || (c >= 0xFD50 && c <= 0xFD8F) || (c >= 0xFD92 && c <= 0xFDC7) || (c >= 0xFDF0 && c <= 0xFDFC) || (c >= 0xFE70 && c <= 0xFE74) || (c >= 0xFE76 && c <= 0xFEFC) || (c >= 0x10800 && c <= 0x10805) || (c == 0x10808) || (c >= 0x1080A && c <= 0x10835) || (c >= 0x10837 && c <= 0x10838) || (c == 0x1083C) || (c >= 0x1083F && c <= 0x10855) || (c >= 0x10857 && c <= 0x1085F) || (c >= 0x10900 && c <= 0x1091B) || (c >= 0x10920 && c <= 0x10939) || (c == 0x1093F) || (c >= 0x10980 && c <= 0x109B7) || (c >= 0x109BE && c <= 0x109BF) || (c == 0x10A00) || (c >= 0x10A10 && c <= 0x10A13) || (c >= 0x10A15 && c <= 0x10A17) || (c >= 0x10A19 && c <= 0x10A33) || (c >= 0x10A40 && c <= 0x10A47) || (c >= 0x10A50 && c <= 0x10A58) || (c >= 0x10A60 && c <= 0x10A7F) || (c >= 0x10B00 && c <= 0x10B35) || (c >= 0x10B40 && c <= 0x10B55) || (c >= 0x10B58 && c <= 0x10B72) || (c >= 0x10B78 && c <= 0x10B7F) || (c >= 0x10C00 && c <= 0x10C48) || (c >= 0x1EE00 && c <= 0x1EE03) || (c >= 0x1EE05 && c <= 0x1EE1F) || (c >= 0x1EE21 && c <= 0x1EE22) || (c == 0x1EE24) || (c == 0x1EE27) || (c >= 0x1EE29 && c <= 0x1EE32) || (c >= 0x1EE34 && c <= 0x1EE37) || (c == 0x1EE39) || (c == 0x1EE3B) || (c == 0x1EE42) || (c == 0x1EE47) || (c == 0x1EE49) || (c == 0x1EE4B) || (c >= 0x1EE4D && c <= 0x1EE4F) || (c >= 0x1EE51 && c <= 0x1EE52) || (c == 0x1EE54) || (c == 0x1EE57) || (c == 0x1EE59) || (c == 0x1EE5B) || (c == 0x1EE5D) || (c == 0x1EE5F) || (c >= 0x1EE61 && c <= 0x1EE62) || (c == 0x1EE64) || (c >= 0x1EE67 && c <= 0x1EE6A) || (c >= 0x1EE6C && c <= 0x1EE72) || (c >= 0x1EE74 && c <= 0x1EE77) || (c >= 0x1EE79 && c <= 0x1EE7C) || (c == 0x1EE7E) || (c >= 0x1EE80 && c <= 0x1EE89) || (c >= 0x1EE8B && c <= 0x1EE9B) || (c >= 0x1EEA1 && c <= 0x1EEA3) || (c >= 0x1EEA5 && c <= 0x1EEA9) || (c >= 0x1EEAB && c <= 0x1EEBB));
}

BOOL isCodePointStrongLTR(UTF32Char c) {
  return (c >= 0x41 && c <= 0x5A) || (c >= 0x61 && c <= 0x7A) || (c == 0xAA) || (c == 0xB5) || (c == 0xBA) || (c >= 0xC0 && c <= 0xD6) || (c >= 0xD8 && c <= 0xF6) || (c >= 0xF8 && c <= 0x2B8) || (c >= 0x2BB && c <= 0x2C1) || (c >= 0x2D0 && c <= 0x2D1) || (c >= 0x2E0 && c <= 0x2E4) || (c == 0x2EE) || (c >= 0x370 && c <= 0x373) || (c >= 0x376 && c <= 0x377) || (c >= 0x37A && c <= 0x37D) || (c == 0x386) || (c >= 0x388 && c <= 0x38A) || (c == 0x38C) || (c >= 0x38E && c <= 0x3A1) || (c >= 0x3A3 && c <= 0x3F5) || (c >= 0x3F7 && c <= 0x482) || (c >= 0x48A && c <= 0x527) || (c >= 0x531 && c <= 0x556) || (c >= 0x559 && c <= 0x55F) || (c >= 0x561 && c <= 0x587) || (c == 0x589) || (c >= 0x903 && c <= 0x939) || (c == 0x93B) || (c >= 0x93D && c <= 0x940) || (c >= 0x949 && c <= 0x94C) || (c >= 0x94E && c <= 0x950) || (c >= 0x958 && c <= 0x961) || (c >= 0x964 && c <= 0x977) || (c >= 0x979 && c <= 0x97F) || (c >= 0x982 && c <= 0x983) || (c >= 0x985 && c <= 0x98C) || (c >= 0x98F && c <= 0x990) || (c >= 0x993 && c <= 0x9A8) || (c >= 0x9AA && c <= 0x9B0) || (c == 0x9B2) || (c >= 0x9B6 && c <= 0x9B9) || (c >= 0x9BD && c <= 0x9C0) || (c >= 0x9C7 && c <= 0x9C8) || (c >= 0x9CB && c <= 0x9CC) || (c == 0x9CE) || (c == 0x9D7) || (c >= 0x9DC && c <= 0x9DD) || (c >= 0x9DF && c <= 0x9E1) || (c >= 0x9E6 && c <= 0x9F1) || (c >= 0x9F4 && c <= 0x9FA) || (c == 0xA03) || (c >= 0xA05 && c <= 0xA0A) || (c >= 0xA0F && c <= 0xA10) || (c >= 0xA13 && c <= 0xA28) || (c >= 0xA2A && c <= 0xA30) || (c >= 0xA32 && c <= 0xA33) || (c >= 0xA35 && c <= 0xA36) || (c >= 0xA38 && c <= 0xA39) || (c >= 0xA3E && c <= 0xA40) || (c >= 0xA59 && c <= 0xA5C) || (c == 0xA5E) || (c >= 0xA66 && c <= 0xA6F) || (c >= 0xA72 && c <= 0xA74) || (c == 0xA83) || (c >= 0xA85 && c <= 0xA8D) || (c >= 0xA8F && c <= 0xA91) || (c >= 0xA93 && c <= 0xAA8) || (c >= 0xAAA && c <= 0xAB0) || (c >= 0xAB2 && c <= 0xAB3) || (c >= 0xAB5 && c <= 0xAB9) || (c >= 0xABD && c <= 0xAC0) || (c == 0xAC9) || (c >= 0xACB && c <= 0xACC) || (c == 0xAD0) || (c >= 0xAE0 && c <= 0xAE1) || (c >= 0xAE6 && c <= 0xAF0) || (c >= 0xB02 && c <= 0xB03) || (c >= 0xB05 && c <= 0xB0C) || (c >= 0xB0F && c <= 0xB10) || (c >= 0xB13 && c <= 0xB28) || (c >= 0xB2A && c <= 0xB30) || (c >= 0xB32 && c <= 0xB33) || (c >= 0xB35 && c <= 0xB39) || (c >= 0xB3D && c <= 0xB3E) || (c == 0xB40) || (c >= 0xB47 && c <= 0xB48) || (c >= 0xB4B && c <= 0xB4C) || (c == 0xB57) || (c >= 0xB5C && c <= 0xB5D) || (c >= 0xB5F && c <= 0xB61) || (c >= 0xB66 && c <= 0xB77) || (c == 0xB83) || (c >= 0xB85 && c <= 0xB8A) || (c >= 0xB8E && c <= 0xB90) || (c >= 0xB92 && c <= 0xB95) || (c >= 0xB99 && c <= 0xB9A) || (c == 0xB9C) || (c >= 0xB9E && c <= 0xB9F) || (c >= 0xBA3 && c <= 0xBA4) || (c >= 0xBA8 && c <= 0xBAA) || (c >= 0xBAE && c <= 0xBB9) || (c >= 0xBBE && c <= 0xBBF) || (c >= 0xBC1 && c <= 0xBC2) || (c >= 0xBC6 && c <= 0xBC8) || (c >= 0xBCA && c <= 0xBCC) || (c == 0xBD0) || (c == 0xBD7) || (c >= 0xBE6 && c <= 0xBF2) || (c >= 0xC01 && c <= 0xC03) || (c >= 0xC05 && c <= 0xC0C) || (c >= 0xC0E && c <= 0xC10) || (c >= 0xC12 && c <= 0xC28) || (c >= 0xC2A && c <= 0xC33) || (c >= 0xC35 && c <= 0xC39) || (c == 0xC3D) || (c >= 0xC41 && c <= 0xC44) || (c >= 0xC58 && c <= 0xC59) || (c >= 0xC60 && c <= 0xC61) || (c >= 0xC66 && c <= 0xC6F) || (c == 0xC7F) || (c >= 0xC82 && c <= 0xC83) || (c >= 0xC85 && c <= 0xC8C) || (c >= 0xC8E && c <= 0xC90) || (c >= 0xC92 && c <= 0xCA8) || (c >= 0xCAA && c <= 0xCB3) || (c >= 0xCB5 && c <= 0xCB9) || (c >= 0xCBD && c <= 0xCC4) || (c >= 0xCC6 && c <= 0xCC8) || (c >= 0xCCA && c <= 0xCCB) || (c >= 0xCD5 && c <= 0xCD6) || (c == 0xCDE) || (c >= 0xCE0 && c <= 0xCE1) || (c >= 0xCE6 && c <= 0xCEF) || (c >= 0xCF1 && c <= 0xCF2) || (c >= 0xD02 && c <= 0xD03) || (c >= 0xD05 && c <= 0xD0C) || (c >= 0xD0E && c <= 0xD10) || (c >= 0xD12 && c <= 0xD3A) || (c >= 0xD3D && c <= 0xD40) || (c >= 0xD46 && c <= 0xD48) || (c >= 0xD4A && c <= 0xD4C) || (c == 0xD4E) || (c == 0xD57) || (c >= 0xD60 && c <= 0xD61) || (c >= 0xD66 && c <= 0xD75) || (c >= 0xD79 && c <= 0xD7F) || (c >= 0xD82 && c <= 0xD83) || (c >= 0xD85 && c <= 0xD96) || (c >= 0xD9A && c <= 0xDB1) || (c >= 0xDB3 && c <= 0xDBB) || (c == 0xDBD) || (c >= 0xDC0 && c <= 0xDC6) || (c >= 0xDCF && c <= 0xDD1) || (c >= 0xDD8 && c <= 0xDDF) || (c >= 0xDF2 && c <= 0xDF4) || (c >= 0xE01 && c <= 0xE30) || (c >= 0xE32 && c <= 0xE33) || (c >= 0xE40 && c <= 0xE46) || (c >= 0xE4F && c <= 0xE5B) || (c >= 0xE81 && c <= 0xE82) || (c == 0xE84) || (c >= 0xE87 && c <= 0xE88) || (c == 0xE8A) || (c == 0xE8D) || (c >= 0xE94 && c <= 0xE97) || (c >= 0xE99 && c <= 0xE9F) || (c >= 0xEA1 && c <= 0xEA3) || (c == 0xEA5) || (c == 0xEA7) || (c >= 0xEAA && c <= 0xEAB) || (c >= 0xEAD && c <= 0xEB0) || (c >= 0xEB2 && c <= 0xEB3) || (c == 0xEBD) || (c >= 0xEC0 && c <= 0xEC4) || (c == 0xEC6) || (c >= 0xED0 && c <= 0xED9) || (c >= 0xEDC && c <= 0xEDF) || (c >= 0xF00 && c <= 0xF17) || (c >= 0xF1A && c <= 0xF34) || (c == 0xF36) || (c == 0xF38) || (c >= 0xF3E && c <= 0xF47) || (c >= 0xF49 && c <= 0xF6C) || (c == 0xF7F) || (c == 0xF85) || (c >= 0xF88 && c <= 0xF8C) || (c >= 0xFBE && c <= 0xFC5) || (c >= 0xFC7 && c <= 0xFCC) || (c >= 0xFCE && c <= 0xFDA) || (c >= 0x1000 && c <= 0x102C) || (c == 0x1031) || (c == 0x1038) || (c >= 0x103B && c <= 0x103C) || (c >= 0x103F && c <= 0x1057) || (c >= 0x105A && c <= 0x105D) || (c >= 0x1061 && c <= 0x1070) || (c >= 0x1075 && c <= 0x1081) || (c >= 0x1083 && c <= 0x1084) || (c >= 0x1087 && c <= 0x108C) || (c >= 0x108E && c <= 0x109C) || (c >= 0x109E && c <= 0x10C5) || (c == 0x10C7) || (c == 0x10CD) || (c >= 0x10D0 && c <= 0x1248) || (c >= 0x124A && c <= 0x124D) || (c >= 0x1250 && c <= 0x1256) || (c == 0x1258) || (c >= 0x125A && c <= 0x125D) || (c >= 0x1260 && c <= 0x1288) || (c >= 0x128A && c <= 0x128D) || (c >= 0x1290 && c <= 0x12B0) || (c >= 0x12B2 && c <= 0x12B5) || (c >= 0x12B8 && c <= 0x12BE) || (c == 0x12C0) || (c >= 0x12C2 && c <= 0x12C5) || (c >= 0x12C8 && c <= 0x12D6) || (c >= 0x12D8 && c <= 0x1310) || (c >= 0x1312 && c <= 0x1315) || (c >= 0x1318 && c <= 0x135A) || (c >= 0x1360 && c <= 0x137C) || (c >= 0x1380 && c <= 0x138F) || (c >= 0x13A0 && c <= 0x13F4) || (c >= 0x1401 && c <= 0x167F) || (c >= 0x1681 && c <= 0x169A) || (c >= 0x16A0 && c <= 0x16F0) || (c >= 0x1700 && c <= 0x170C) || (c >= 0x170E && c <= 0x1711) || (c >= 0x1720 && c <= 0x1731) || (c >= 0x1735 && c <= 0x1736) || (c >= 0x1740 && c <= 0x1751) || (c >= 0x1760 && c <= 0x176C) || (c >= 0x176E && c <= 0x1770) || (c >= 0x1780 && c <= 0x17B3) || (c == 0x17B6) || (c >= 0x17BE && c <= 0x17C5) || (c >= 0x17C7 && c <= 0x17C8) || (c >= 0x17D4 && c <= 0x17DA) || (c == 0x17DC) || (c >= 0x17E0 && c <= 0x17E9) || (c >= 0x1810 && c <= 0x1819) || (c >= 0x1820 && c <= 0x1877) || (c >= 0x1880 && c <= 0x18A8) || (c == 0x18AA) || (c >= 0x18B0 && c <= 0x18F5) || (c >= 0x1900 && c <= 0x191C) || (c >= 0x1923 && c <= 0x1926) || (c >= 0x1929 && c <= 0x192B) || (c >= 0x1930 && c <= 0x1931) || (c >= 0x1933 && c <= 0x1938) || (c >= 0x1946 && c <= 0x196D) || (c >= 0x1970 && c <= 0x1974) || (c >= 0x1980 && c <= 0x19AB) || (c >= 0x19B0 && c <= 0x19C9) || (c >= 0x19D0 && c <= 0x19DA) || (c >= 0x1A00 && c <= 0x1A16) || (c >= 0x1A19 && c <= 0x1A1B) || (c >= 0x1A1E && c <= 0x1A55) || (c == 0x1A57) || (c == 0x1A61) || (c >= 0x1A63 && c <= 0x1A64) || (c >= 0x1A6D && c <= 0x1A72) || (c >= 0x1A80 && c <= 0x1A89) || (c >= 0x1A90 && c <= 0x1A99) || (c >= 0x1AA0 && c <= 0x1AAD) || (c >= 0x1B04 && c <= 0x1B33) || (c == 0x1B35) || (c == 0x1B3B) || (c >= 0x1B3D && c <= 0x1B41) || (c >= 0x1B43 && c <= 0x1B4B) || (c >= 0x1B50 && c <= 0x1B6A) || (c >= 0x1B74 && c <= 0x1B7C) || (c >= 0x1B82 && c <= 0x1BA1) || (c >= 0x1BA6 && c <= 0x1BA7) || (c == 0x1BAA) || (c >= 0x1BAC && c <= 0x1BE5) || (c == 0x1BE7) || (c >= 0x1BEA && c <= 0x1BEC) || (c == 0x1BEE) || (c >= 0x1BF2 && c <= 0x1BF3) || (c >= 0x1BFC && c <= 0x1C2B) || (c >= 0x1C34 && c <= 0x1C35) || (c >= 0x1C3B && c <= 0x1C49) || (c >= 0x1C4D && c <= 0x1C7F) || (c >= 0x1CC0 && c <= 0x1CC7) || (c == 0x1CD3) || (c == 0x1CE1) || (c >= 0x1CE9 && c <= 0x1CEC) || (c >= 0x1CEE && c <= 0x1CF3) || (c >= 0x1CF5 && c <= 0x1CF6) || (c >= 0x1D00 && c <= 0x1DBF) || (c >= 0x1E00 && c <= 0x1F15) || (c >= 0x1F18 && c <= 0x1F1D) || (c >= 0x1F20 && c <= 0x1F45) || (c >= 0x1F48 && c <= 0x1F4D) || (c >= 0x1F50 && c <= 0x1F57) || (c == 0x1F59) || (c == 0x1F5B) || (c == 0x1F5D) || (c >= 0x1F5F && c <= 0x1F7D) || (c >= 0x1F80 && c <= 0x1FB4) || (c >= 0x1FB6 && c <= 0x1FBC) || (c == 0x1FBE) || (c >= 0x1FC2 && c <= 0x1FC4) || (c >= 0x1FC6 && c <= 0x1FCC) || (c >= 0x1FD0 && c <= 0x1FD3) || (c >= 0x1FD6 && c <= 0x1FDB) || (c >= 0x1FE0 && c <= 0x1FEC) || (c >= 0x1FF2 && c <= 0x1FF4) || (c >= 0x1FF6 && c <= 0x1FFC) || (c == 0x200E) || (c == 0x2071) || (c == 0x207F) || (c >= 0x2090 && c <= 0x209C) || (c == 0x2102) || (c == 0x2107) || (c >= 0x210A && c <= 0x2113) || (c == 0x2115) || (c >= 0x2119 && c <= 0x211D) || (c == 0x2124) || (c == 0x2126) || (c == 0x2128) || (c >= 0x212A && c <= 0x212D) || (c >= 0x212F && c <= 0x2139) || (c >= 0x213C && c <= 0x213F) || (c >= 0x2145 && c <= 0x2149) || (c >= 0x214E && c <= 0x214F) || (c >= 0x2160 && c <= 0x2188) || (c >= 0x2336 && c <= 0x237A) || (c == 0x2395) || (c >= 0x249C && c <= 0x24E9) || (c == 0x26AC) || (c >= 0x2800 && c <= 0x28FF) || (c >= 0x2C00 && c <= 0x2C2E) || (c >= 0x2C30 && c <= 0x2C5E) || (c >= 0x2C60 && c <= 0x2CE4) || (c >= 0x2CEB && c <= 0x2CEE) || (c >= 0x2CF2 && c <= 0x2CF3) || (c >= 0x2D00 && c <= 0x2D25) || (c == 0x2D27) || (c == 0x2D2D) || (c >= 0x2D30 && c <= 0x2D67) || (c >= 0x2D6F && c <= 0x2D70) || (c >= 0x2D80 && c <= 0x2D96) || (c >= 0x2DA0 && c <= 0x2DA6) || (c >= 0x2DA8 && c <= 0x2DAE) || (c >= 0x2DB0 && c <= 0x2DB6) || (c >= 0x2DB8 && c <= 0x2DBE) || (c >= 0x2DC0 && c <= 0x2DC6) || (c >= 0x2DC8 && c <= 0x2DCE) || (c >= 0x2DD0 && c <= 0x2DD6) || (c >= 0x2DD8 && c <= 0x2DDE) || (c >= 0x3005 && c <= 0x3007) || (c >= 0x3021 && c <= 0x3029) || (c >= 0x302E && c <= 0x302F) || (c >= 0x3031 && c <= 0x3035) || (c >= 0x3038 && c <= 0x303C) || (c >= 0x3041 && c <= 0x3096) || (c >= 0x309D && c <= 0x309F) || (c >= 0x30A1 && c <= 0x30FA) || (c >= 0x30FC && c <= 0x30FF) || (c >= 0x3105 && c <= 0x312D) || (c >= 0x3131 && c <= 0x318E) || (c >= 0x3190 && c <= 0x31BA) || (c >= 0x31F0 && c <= 0x321C) || (c >= 0x3220 && c <= 0x324F) || (c >= 0x3260 && c <= 0x327B) || (c >= 0x327F && c <= 0x32B0) || (c >= 0x32C0 && c <= 0x32CB) || (c >= 0x32D0 && c <= 0x32FE) || (c >= 0x3300 && c <= 0x3376) || (c >= 0x337B && c <= 0x33DD) || (c >= 0x33E0 && c <= 0x33FE) || (c == 0x3400) || (c == 0x4DB5) || (c == 0x4E00) || (c == 0x9FCC) || (c >= 0xA000 && c <= 0xA48C) || (c >= 0xA4D0 && c <= 0xA60C) || (c >= 0xA610 && c <= 0xA62B) || (c >= 0xA640 && c <= 0xA66E) || (c >= 0xA680 && c <= 0xA697) || (c >= 0xA6A0 && c <= 0xA6EF) || (c >= 0xA6F2 && c <= 0xA6F7) || (c >= 0xA722 && c <= 0xA787) || (c >= 0xA789 && c <= 0xA78E) || (c >= 0xA790 && c <= 0xA793) || (c >= 0xA7A0 && c <= 0xA7AA) || (c >= 0xA7F8 && c <= 0xA801) || (c >= 0xA803 && c <= 0xA805) || (c >= 0xA807 && c <= 0xA80A) || (c >= 0xA80C && c <= 0xA824) || (c == 0xA827) || (c >= 0xA830 && c <= 0xA837) || (c >= 0xA840 && c <= 0xA873) || (c >= 0xA880 && c <= 0xA8C3) || (c >= 0xA8CE && c <= 0xA8D9) || (c >= 0xA8F2 && c <= 0xA8FB) || (c >= 0xA900 && c <= 0xA925) || (c >= 0xA92E && c <= 0xA946) || (c >= 0xA952 && c <= 0xA953) || (c >= 0xA95F && c <= 0xA97C) || (c >= 0xA983 && c <= 0xA9B2) || (c >= 0xA9B4 && c <= 0xA9B5) || (c >= 0xA9BA && c <= 0xA9BB) || (c >= 0xA9BD && c <= 0xA9CD) || (c >= 0xA9CF && c <= 0xA9D9) || (c >= 0xA9DE && c <= 0xA9DF) || (c >= 0xAA00 && c <= 0xAA28) || (c >= 0xAA2F && c <= 0xAA30) || (c >= 0xAA33 && c <= 0xAA34) || (c >= 0xAA40 && c <= 0xAA42) || (c >= 0xAA44 && c <= 0xAA4B) || (c == 0xAA4D) || (c >= 0xAA50 && c <= 0xAA59) || (c >= 0xAA5C && c <= 0xAA7B) || (c >= 0xAA80 && c <= 0xAAAF) || (c == 0xAAB1) || (c >= 0xAAB5 && c <= 0xAAB6) || (c >= 0xAAB9 && c <= 0xAABD) || (c == 0xAAC0) || (c == 0xAAC2) || (c >= 0xAADB && c <= 0xAAEB) || (c >= 0xAAEE && c <= 0xAAF5) || (c >= 0xAB01 && c <= 0xAB06) || (c >= 0xAB09 && c <= 0xAB0E) || (c >= 0xAB11 && c <= 0xAB16) || (c >= 0xAB20 && c <= 0xAB26) || (c >= 0xAB28 && c <= 0xAB2E) || (c >= 0xABC0 && c <= 0xABE4) || (c >= 0xABE6 && c <= 0xABE7) || (c >= 0xABE9 && c <= 0xABEC) || (c >= 0xABF0 && c <= 0xABF9) || (c == 0xAC00) || (c == 0xD7A3) || (c >= 0xD7B0 && c <= 0xD7C6) || (c >= 0xD7CB && c <= 0xD7FB) || (c == 0xD800) || (c >= 0xDB7F && c <= 0xDB80) || (c >= 0xDBFF && c <= 0xDC00) || (c >= 0xDFFF && c <= 0xE000) || (c >= 0xF8FF && c <= 0xFA6D) || (c >= 0xFA70 && c <= 0xFAD9) || (c >= 0xFB00 && c <= 0xFB06) || (c >= 0xFB13 && c <= 0xFB17) || (c >= 0xFF21 && c <= 0xFF3A) || (c >= 0xFF41 && c <= 0xFF5A) || (c >= 0xFF66 && c <= 0xFFBE) || (c >= 0xFFC2 && c <= 0xFFC7) || (c >= 0xFFCA && c <= 0xFFCF) || (c >= 0xFFD2 && c <= 0xFFD7) || (c >= 0xFFDA && c <= 0xFFDC) || (c >= 0x10000 && c <= 0x1000B) || (c >= 0x1000D && c <= 0x10026) || (c >= 0x10028 && c <= 0x1003A) || (c >= 0x1003C && c <= 0x1003D) || (c >= 0x1003F && c <= 0x1004D) || (c >= 0x10050 && c <= 0x1005D) || (c >= 0x10080 && c <= 0x100FA) || (c == 0x10100) || (c == 0x10102) || (c >= 0x10107 && c <= 0x10133) || (c >= 0x10137 && c <= 0x1013F) || (c >= 0x101D0 && c <= 0x101FC) || (c >= 0x10280 && c <= 0x1029C) || (c >= 0x102A0 && c <= 0x102D0) || (c >= 0x10300 && c <= 0x1031E) || (c >= 0x10320 && c <= 0x10323) || (c >= 0x10330 && c <= 0x1034A) || (c >= 0x10380 && c <= 0x1039D) || (c >= 0x1039F && c <= 0x103C3) || (c >= 0x103C8 && c <= 0x103D5) || (c >= 0x10400 && c <= 0x1049D) || (c >= 0x104A0 && c <= 0x104A9) || (c == 0x11000) || (c >= 0x11002 && c <= 0x11037) || (c >= 0x11047 && c <= 0x1104D) || (c >= 0x11066 && c <= 0x1106F) || (c >= 0x11082 && c <= 0x110B2) || (c >= 0x110B7 && c <= 0x110B8) || (c >= 0x110BB && c <= 0x110C1) || (c >= 0x110D0 && c <= 0x110E8) || (c >= 0x110F0 && c <= 0x110F9) || (c >= 0x11103 && c <= 0x11126) || (c == 0x1112C) || (c >= 0x11136 && c <= 0x11143) || (c >= 0x11182 && c <= 0x111B5) || (c >= 0x111BF && c <= 0x111C8) || (c >= 0x111D0 && c <= 0x111D9) || (c >= 0x11680 && c <= 0x116AA) || (c == 0x116AC) || (c >= 0x116AE && c <= 0x116AF) || (c == 0x116B6) || (c >= 0x116C0 && c <= 0x116C9) || (c >= 0x12000 && c <= 0x1236E) || (c >= 0x12400 && c <= 0x12462) || (c >= 0x12470 && c <= 0x12473) || (c >= 0x13000 && c <= 0x1342E) || (c >= 0x16800 && c <= 0x16A38) || (c >= 0x16F00 && c <= 0x16F44) || (c >= 0x16F50 && c <= 0x16F7E) || (c >= 0x16F93 && c <= 0x16F9F) || (c >= 0x1B000 && c <= 0x1B001) || (c >= 0x1D000 && c <= 0x1D0F5) || (c >= 0x1D100 && c <= 0x1D126) || (c >= 0x1D129 && c <= 0x1D166) || (c >= 0x1D16A && c <= 0x1D172) || (c >= 0x1D183 && c <= 0x1D184) || (c >= 0x1D18C && c <= 0x1D1A9) || (c >= 0x1D1AE && c <= 0x1D1DD) || (c >= 0x1D360 && c <= 0x1D371) || (c >= 0x1D400 && c <= 0x1D454) || (c >= 0x1D456 && c <= 0x1D49C) || (c >= 0x1D49E && c <= 0x1D49F) || (c == 0x1D4A2) || (c >= 0x1D4A5 && c <= 0x1D4A6) || (c >= 0x1D4A9 && c <= 0x1D4AC) || (c >= 0x1D4AE && c <= 0x1D4B9) || (c == 0x1D4BB) || (c >= 0x1D4BD && c <= 0x1D4C3) || (c >= 0x1D4C5 && c <= 0x1D505) || (c >= 0x1D507 && c <= 0x1D50A) || (c >= 0x1D50D && c <= 0x1D514) || (c >= 0x1D516 && c <= 0x1D51C) || (c >= 0x1D51E && c <= 0x1D539) || (c >= 0x1D53B && c <= 0x1D53E) || (c >= 0x1D540 && c <= 0x1D544) || (c == 0x1D546) || (c >= 0x1D54A && c <= 0x1D550) || (c >= 0x1D552 && c <= 0x1D6A5) || (c >= 0x1D6A8 && c <= 0x1D6DA) || (c >= 0x1D6DC && c <= 0x1D714) || (c >= 0x1D716 && c <= 0x1D74E) || (c >= 0x1D750 && c <= 0x1D788) || (c >= 0x1D78A && c <= 0x1D7C2) || (c >= 0x1D7C4 && c <= 0x1D7CB) || (c >= 0x1F110 && c <= 0x1F12E) || (c >= 0x1F130 && c <= 0x1F169) || (c >= 0x1F170 && c <= 0x1F19A) || (c >= 0x1F1E6 && c <= 0x1F202) || (c >= 0x1F210 && c <= 0x1F23A) || (c >= 0x1F240 && c <= 0x1F248) || (c >= 0x1F250 && c <= 0x1F251) || (c == 0x20000) || (c == 0x2A6D6) || (c == 0x2A700) || (c == 0x2B734) || (c == 0x2B740) || (c == 0x2B81D) || (c >= 0x2F800 && c <= 0x2FA1D) || (c == 0xF0000) || (c == 0xFFFFD) || (c == 0x100000) || (c == 0x10FFFD);
}   

-(int)getBaseDirection {
  // Decode string into UTF32.
  NSData *utf32data = [self dataUsingEncoding:NSUTF32StringEncoding];
  // NSUTF32StringEncoding has the platform's byte-order, which should
  // be the same as UTF32Char's.
  UTF32Char *utf32chars = (UTF32Char *)[utf32data bytes];

  for (NSUInteger i = 0; i < self.length; i++) {
    // UTF32 is a fixed-length encoding, so utf32chars[i] will
    // always give us the i'th character.
    if (isCodePointStrongRTL(utf32chars[i]))
      return -1;
    if (isCodePointStrongLTR(utf32chars[i]))
      return 1;
  }
  return 0;
}

@end

更长的回答：生成函数 isCodePointStrong{RTL，LTR}

  1. Create a script hex_numbers_to_dec_ranges_py,

    import sys
from itertools import groupby, count

numberlist = []
for line in sys.stdin:
    numberlist.append(int(line, 16));

def as_range(iterable): # not sure how to do this part elegantly
    l = list(iterable)
    if len(l) > 1:
        return '(c >= 0x{0:X} && c <= 0x{1:X})'.format(l[0], l[-1])
    else:
        return '(c == 0x{0:X})'.format(l[0])

print ' || '.join(as_range(g) for _, g in groupby(numberlist, lambda n, c=count(): n-next(c)))

    (code shamelessly stolen from this excellent answer at StackExhange's Code Review).

  2. Run from a terminal:

    curl http://www.unicode.org/Public/UNIDATA/UnicodeData.txt > /tmp/UnicodeData.txt
cat /tmp/UnicodeData.txt | awk -F';' '$5 == "R" || $5 == "AL"' | cut -d';' -f1 | python hex_numbers_to_dec_ranges.py > rtl.m
cat /tmp/UnicodeData.txt | awk -F';' '$5 == "L"' | cut -d';' -f1 | python hex_numbers_to_dec_ranges.py > ltr.m
rm /tmp/UnicodeData.txt

编辑：正如@masmor正确指出的那样，在getBaseDirection中的for循环扫描字符而不是字节。因此，它应该在“字符”迭代次数之后终止，而不是“字节”迭代次数之后。换句话说，应该是self.length次而不是utf32data.length次。代码现已更正。

我一直在使用这段代码，但是最新的编译器开始出现了很多警告，指出其中一些比较语句将始终返回false：return ... (c >= 0x10800 && c <= 0x10805)...。这是因为unichar是unsigned short类型，其最大值为0xFFFF，而这些常量的值大于此范围。这些常量来自哪里？也许我应该创建一个新的问题来解决。 - progrmr
嗯...看起来unichar代表UTF-16字符，而我解析的数据描述了Unicode码点（每个码点需要32位）。因此，我的代码可能会对需要使用多个unichar表示的Unicode代理项字符得出错误结果。代码应该被修改以考虑代理项字符；我可能会在周末处理这个问题。 - user1071136
有什么建议如何处理这个问题吗？ - progrmr
1
据我所知，警告已得到解决（我无法让我的XCode输出警告），扫描功能也已纠正。如果修复内容不明确，请让我知道。 - user1071136
那个完美运作。更新得很好！顺便说一句，我只在XCode 5中收到警告。 - progrmr
2
我认为在已接受的答案中，-getBaseDirection 中的扫描循环应该是针对 self.length 而不是 utf32data.length 的。 utf32data.length 是以字节为单位的大小，而 sizeof(UTF32Char) == 4，这将导致溢出。
实际上，当前代码会间歇性地对相同输入返回错误结果，这取决于它溢出到了什么位置（也许在某个非常糟糕的日子里会导致段错误）。除此之外，修复后似乎一切都正常运作。
你说得对！我会修正答案。但是，这不应该是一个答案；你能把它改成评论吗？ - user1071136
我看到你已经尝试过一次进行这个编辑了 - 我很抱歉错过了它，也感谢你没有放弃 :) - user1071136
是的，我猜测它被拒绝是因为试图编辑您的代码。评论是我的最初想法，但遗憾的是我没有足够的声望... 我还是 SO 贡献方面的新手！ - voxlet
1
在HTML5中，可以通过将dir="auto"应用于元素来实现。它已经在WebKit中实现了，但我不完全确定它是否在iOS中可用。
dir="auto"非常简单，您可能可以自己实现它-只需搜索具有强方向性的第一个字符，并将其方向性应用于整个内容。
如果在iOS中找不到任何东西，您可以尝试从StatusNet实现它的方式中获取一些更聪明的想法：http://status.net/sites/default/files/issues/1346_jquery.directionDetector.js
这实际上是一个好主意 - 只需检查第一个字符。我猜有指定这个的表格，但问题是是否已经有用c/objective-c编写的代码了。 - user1071136
0

ICU 项目提供了实现您所需功能的方法。在 Xcode 11 中，可以将 ICU 库链接到 iOS 应用程序或 iOS 框架目标中。要这样做，请打开您的目标，在“常规”选项卡下的“框架和库”中添加libicucore.tbd。

Adding libicucore in Xcode

有时候，如果你这样做，Xcode可能会选择macOS版本的库，这种情况下，你会在项目文件中看到类似于这样的内容。

ABCDEFGHIJKLMNOPQRSTUVWX /* libicucore.tbd */ = {isa = PBXFileReference; lastKnownFileType = "sourcecode.text-based-dylib-definition"; name = libicucore.tbd; path = Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/lib/libicucore.tbd; sourceTree = DEVELOPER_DIR; };

要强制使用iOS变体，只需使用文本编辑器编辑项目文件，使该行看起来像这样

ABCDEFGHIJKLMNOPQRSTUVWX /* libicucore.tbd */ = {isa = PBXFileReference; lastKnownFileType = "sourcecode.text-based-dylib-definition"; name = libicucore.tbd; path = usr/lib/libicucore.tbd; sourceTree = SDKROOT; };

不幸的是，iOS附带的库版本有点旧，不包括ubidi_getBaseDirection。但是，有一个方法u_charDirection可以用来重建ubidi_getBaseDirection。只需遍历字符串中的字符并返回具有强方向性的第一个字符的方向即可。以下是在Swift中执行此操作的示例（Objective-C端口应该很简单）。

enum Direction {
    case leftToRight
    case rightToLeft
    case neutral
}

func ubidi_getBaseDirection(of string: String) -> Direction {
    guard let data = string.data(using: .utf32) else {
        return .leftToRight
    }
    let chars = data.withUnsafeBytes { $0.bindMemory(to: UChar32.self) }
    for c in chars {
        let direction = u_charDirection(c)
        if direction == U_RIGHT_TO_LEFT || direction == U_RIGHT_TO_LEFT_ARABIC {
            return .rightToLeft
        } else if direction == U_LEFT_TO_RIGHT {
            return .leftToRight
        }
    }
    return .neutral
}

请注意，由于libicucore是一个纯C库，如果您在Swift中工作，则需要将其添加到您的桥接头文件/伞形头文件中。我发现以下内容就足够了。
#include "unicode/utypes.h"
0

2022 更新

您可以使用自 iOS 12 开始提供的 NLLanguageRecognizer：

import NaturalLanguage

extension String {
    var isRightToLeft: Bool {
        guard let language = NLLanguageRecognizer.dominantLanguage(for: self) else {
            return false
        }

        switch language {
        case .arabic, .hebrew, .persian, .urdu:
            return true
        default:
            return false
        }
    }
}
0

有一种解决方案是基于字符串的语言检测。

如果无法确定方向，则该方法返回NSTextAlignmentNatural。

@implementation NSString (StringAlignmentDetection)

- (NSTextAlignment)naturalTextAligment
{
    NSArray *tagschemes = [NSArray arrayWithObjects:NSLinguisticTagSchemeLanguage, nil];
    NSLinguisticTagger *tagger = [[NSLinguisticTagger alloc] initWithTagSchemes:tagschemes options:0];
    [tagger setString:self];
    NSString *language = [tagger tagAtIndex:0 scheme:NSLinguisticTagSchemeLanguage tokenRange:NULL sentenceRange:NULL];

    NSTextAlignment alignment = NSTextAlignmentNatural;

    if(!language)
    {
        return alignment;
    }

    NSLocaleLanguageDirection direction = [NSLocale characterDirectionForLanguage: language];

    switch (direction)
    {
        case NSLocaleLanguageDirectionLeftToRight:
            alignment = NSTextAlignmentLeft;
            break;

        case NSLocaleLanguageDirectionRightToLeft:
            alignment = NSTextAlignmentRight;
            break;

        default:
            alignment = NSTextAlignmentNatural;
            break;
    }

    return alignment;
}

@end
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