xcode 目标 c 不喜欢我的 unichars？

Objective c doesn't like my unichars?

提问by corydoras

Xcode complaints about "multi-character character contant"'s when I try to do the following:

当我尝试执行以下操作时，Xcode 会抱怨“多字符字符常量”：

static unichar accent characters[] = { 'ā', 'á', '?', 'à' };

How do you make an array of characters, when not all of them are ascii? The following works just fine

当并非所有字符都是 ascii 时，如何制作字符数组？以下工作正常

static unichar accent[] = { 'a', 'b', 'c' }; 

Workaround

解决方法

The closest work around I have found is to convert the special characters into hex, ie this works:

我发现的最接近的工作是将特殊字符转换为十六进制，即这有效：

static unichar accent characters[] = { 0x0100, 0x0101, 0x0102 };

回答by Yuji

It's not that Objective-C doesn't like it, it's that C doesn't. The constant 'c'is for charwhich has 1 byte, not unicharwhich has 2 bytes. (see the note below for a bit more detail.)

并不是Objective-C 不喜欢它，而是C 不喜欢它。常量'c'是char有 1 个字节的，而不是unichar有 2 个字节的。（有关更多详细信息，请参阅下面的注释。）

There's no perfectly supported way to represent a unicharconstant. You can use

没有完全支持的方式来表示unichar常量。您可以使用

char* s="ü";

in a UTF-8-encoded source file to get the unicode C-string, or

在 UTF-8 编码的源文件中获取 unicode C 字符串，或

NSString* s=@"ü";

in a UTF-8 encoded source file to get an NSString. (This was not possible before 10.5. It's OK for iPhone.)

在 UTF-8 编码的源文件中获取NSString. （这在 10.5 之前是不可能的。iPhone 没问题。）

NSStringitself is conceptually encoding-neutral; but if you want, you can get the unicode character by using -characterAtIndex:.

NSString本身在概念上是编码中立的；但如果你愿意，你可以使用-characterAtIndex:.

Finally two comments:

最后两点意见：

• If you just want to remove accents from the string, you can just use the method like this, without writing the table yourself:

  -(NSString*)stringWithoutAccentsFromString:(NSString*)s
  {
      if (!s) return nil;
      NSMutableString *result = [NSMutableString stringWithString:s];
      CFStringFold((CFMutableStringRef)result, kCFCompareDiacriticInsensitive, NULL);
      return result;
  }
  

  See the document of CFStringFold.

• If you want unicode characters for localization/internationalization, you shouldn't embed the strings in the source code. Instead you should use Localizable.stringsand NSLocalizedString. See here.

• 如果您只想从字符串中删除重音符号，您可以使用这样的方法，而无需自己编写表格：

  -(NSString*)stringWithoutAccentsFromString:(NSString*)s
  {
      if (!s) return nil;
      NSMutableString *result = [NSMutableString stringWithString:s];
      CFStringFold((CFMutableStringRef)result, kCFCompareDiacriticInsensitive, NULL);
      return result;
  }
  

  请参阅CFStringFold的文档。

• 如果您想要用于本地化/国际化的 unicode 字符，则不应在源代码中嵌入字符串。相反，您应该使用Localizable.strings和NSLocalizedString。见这里。

Note: For arcane historical reasons, 'a'is an intin C, see the discussions here. In C++, it's a char. But it doesn't change the fact that writing more than one byte inside '...'is implementation-defined and not recommended. For example, see ISO C Standard 6.4.4.10. However, it was common in classic Mac OS to write the four-letter code enclosed in single quotes, like 'APPL'. But that's another story...

注意：由于神秘的历史原因，在 C 中'a'是一个int，请参阅此处的讨论。在 C++ 中，它是一个char. 但这并没有改变这样一个事实，即在内部写入多个字节'...'是实现定义的，不推荐使用。例如，参见ISO C 标准 6.4.4.10。然而，在经典的 Mac OS 中编写用单引号括起来的四字母代码是很常见的，比如'APPL'. 但那是另一个故事了……

Another complication is that accented letters are not always represented by 1 byte; it depends on the encoding. In UTF-8, it's not. In ISO-8859-1, it is. And unicharshould be in UTF-16. Did you save your source code in UTF-16? I think the default of XCode is UTF-8. GCC might do some encoding conversion depending on the setup, too...

另一个复杂情况是重音字母并不总是由 1 个字节表示；这取决于编码。在 UTF-8 中，它不是。在 ISO-8859-1 中，它是。并且unichar应该是UTF-16。您是否将源代码保存在 UTF-16 中？我认为 XCode 的默认值是 UTF-8。GCC 也可能会根据设置进行一些编码转换...

回答by daniel.gindi

Or you can just do it like this:

或者你可以这样做：

static unichar accent characters[] = { L'ā', L'á', L'?', L'à' };

L is a standard C keyword which says "I'm about to write a UNICODE character or character set".

L 是标准的 C 关键字，表示“我将要编写一个 UNICODE 字符或字符集”。

Works fine for Objective-C too.

也适用于 Objective-C。

Note: The compiler may give you a strange warning about too many characters put inside a unichar, but you can safely ignore that warning. Xcode just doesn't deal with the unicode characters the right way, but the compiler parses them properly and the result is OK.

注意：编译器可能会给您一个奇怪的警告，提示您在 unichar 中放入过多字符，但您可以放心地忽略该警告。Xcode 只是没有以正确的方式处理 unicode 字符，但是编译器正确地解析它们并且结果没问题。

回答by Matt Comi

Depending on your circumstances, this may be a tidy way to do it:

根据您的情况，这可能是一种整洁的方法：

NSCharacterSet* accents = 
    [NSCharacterSet characterSetWithCharactersInString:@"āá?à"];

And then, if you want to check if a given unichar is one of those accent characters:

然后，如果您想检查给定的 unichar 是否是这些重音字符之一：

if ([accents characterIsMember:someOtherUnichar])
{
}

NSStringalso has many methods of its own for handling NSCharacterSetobjects.

NSString也有许多自己的方法来处理NSCharacterSet对象。