CFStringTransform处理语言的强大工具 ： 智能地处理用户的输入内容，经典应用场景【索引】

/* Perform string transliteration.  The transformation represented by transform is applied to the given range of string, modifying it in place. Only the specified range will be modified, but the transform may look at portions of the string outside that range for context. NULL range pointer causes the whole string to be transformed. On return, range is modified to reflect the new range corresponding to the original range. reverse indicates that the inverse transform should be used instead, if it exists. If the transform is successful, true is returned; if unsuccessful, false. Reasons for the transform being unsuccessful include an invalid transform identifier, or attempting to reverse an irreversible transform.

You can pass one of the predefined transforms below, or any valid ICU transform ID as defined in the ICU User Guide. Note that we do not support arbitrary set of ICU transform rules.
*/

CF_EXPORT
Boolean CFStringTransform(CFMutableStringRef string, CFRange *range, CFStringRef transform, Boolean reverse);

- (NSString *)pinyin{

    
    NSMutableString *str = [self mutableCopy];
    CFStringTransform(( CFMutableStringRef)str, NULL, kCFStringTransformMandarinLatin, NO);//先转换为带声调的拼音
    CFStringTransform((CFMutableStringRef)str, NULL, kCFStringTransformStripDiacritics, NO);//去掉音标
    return [[str stringByReplacingOccurrencesOfString:@" " withString:@""] lowercaseString];//小写
}