iOS 判定string是不是中文字符

 +(BOOL)IsChinese:(NSString *)str
 {
     for(int i=; i< [str length];i++)
     {
         int a = [str characterAtIndex:i];
         if( a > 0x4e00 && a < 0x9fff)
         {
             return YES;
         }

     }
     return NO;
 }