用字符串识别表情符号字符并重新表达所有字符串

Question

我得到了NSString来自UIWebView包含iPhone的表情符号,但不包括表情符倒车文本.我需要NSString再次显示反向,UIWebView但无法使用表情符号获取反向字符串.我没有在字符串中识别表情符号字符.我有iOS 6.0的xcode 4.5.这是我的代码:

 - (NSString *) createReverseStringFromString:(NSString *)inputString {
  if (inputString.length <= 0)
    return inputString;

 NSMutableString *mutableReverseString = [[NSMutableString alloc] 
 initWithCapacity:inputString.length];
 Thfor (NSInteger i = inputString.length -1; i >= 0; i--) {

    NSString *characterString = [inputString substringWithRange:NSMakeRange(i, 1)];
    [mutableReverseString appendString:characterString];

    NSLog(@"mutableReverseString..%@",mutableReverseString);
 }

 NSString *outputString = [mutableReverseString copy];
 [mutableReverseString release];
return [outputString autorelease];
 }

Answer 1

问题是许多表情符号字符在内部存储为两个字符的"代理对".

例如,"THUMBS UP SIGN"是Unicode点U + 1F44D,但如果将其存储在一个NSString并用于substringWithRange获取单个字符,则会得到两个字符:

U+D83D, U+DC4D

这是U + 1F44D的UTF-16代理对.

当然,如果你反转这两个字符,输出就是垃圾.

解决方案是用于rangeOfComposedCharacterSequenceAtIndex获取"属于一起"的字符序列:

- (NSString *) createReverseStringFromString:(NSString *)inputString {
    if (inputString.length <= 0)
        return inputString;

    NSMutableString *mutableReverseString = [[NSMutableString alloc] 
                         initWithCapacity:inputString.length];

    NSInteger i = inputString.length;
    while (i > 0) {
        NSRange range = [inputString rangeOfComposedCharacterSequenceAtIndex:i-1];
        NSString *characterString = [inputString substringWithRange:range];
        [mutableReverseString appendString:characterString];
        i = range.location;
    }

    NSString *outputString = [mutableReverseString copy];
    return outputString;
}

此函数正确反转包含表情符号字符的字符串.

(注:我省略了一切release,autorelease称因为我总是ARC编译您必须再次补充说,在适当情况下.)