int main(int argc, const char * argv[]) {
   
   NSString *str = @"白日依山尽";
   
   //编码
   NSString *encoderStr = [str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
   
   //解码
   NSString *decoderStr = [encoderStr stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
   
   //字符串打散
   for (int i = 0; i < str.length; i++) {
       NSString *word = [str substringWithRange:NSMakeRange(i, 1)];
       NSLog(@"%@",word);
   }
   
   
   NSLog(@"%@",encoderStr);
   
   NSLog(@"%@",decoderStr);
   
   return 0;
}