Arduino, Bluetooth and iOS device

I would like to try using my iPhone to control Arduino and searched Youtube for some instructional videos. Found a few but the Apps they were using are no longer on the App Store. What is the best free app that will allow me to try some remote control projects using my iPhone. I have looked on the App store but it is not clear if they would useful for what I need. My thoughts are that if I can turn an LED off and on with my iPhone then I should be able to do a multitude of other things using a variety of components. I was going to start with an HC-05 or and HM-10 Bluetooth unit.

Any thoughts or advice would be much appreciated.

Forget the HC-05. It is incompatible with IOS. There was a time when the answer was forget the iPhone, but I think this is no longer the case, and you might get encouragement here. I understand there are variations on the HM-10, but I believe any HM-10 will do for this.

As far as Arduino is concerned, hopefully you can come up with something better than switching a LED with bluetooth - for which the Arduino is likely to be redundant anyway. It might be better to do something useful, and then add the Bluetooth communications, which is really quite easy.

Nick_Pyner:
Forget the HC-05. It is incompatible with IOS.
There was a time when the answer was forget the iPhone, but I think this is no longer the case, and you might get encouragement here. I understand there are variations on the HM-10, but I believe any HM-10 will do for this.

As far as Arduino is concerned, hopefully you can come up with something better than switching a LED with bluetooth - for which the Arduino is likely to be redundant anyway. It might be better to do something useful, and then add the Bluetooth communications, which is really quite easy.

What are the best Apps to use?

Clearly, the app that suits your purpose, whatever that might be, most appropriately.