What Android/iOS programming courses would you recommend?

Question

Mobile development

Greetings!
I am engaged in web development of sites, I have practical experience in writing web applications in PHP, a little Python (but in console mode). Now, due to the high popularity of various mobile devices and gadgets, there is an interest in developing applications for mobile platforms. Since I have little experience in OOP in C # and Java SE, and on the PHP server side, I have already made several test applications for Android OC, including those with a link to a web server. Now I'm using Android Studio 1.4 when developing, there are some questions about design, using xml markup, etc. Of course, google and stackoverflow help me, but they are not always able to solve their tasks and achieve the final goal.
At the moment, there is an opportunity for additional training at the expense of the company in which I work, but that’s not the problem: I didn’t find normal reviews on training companies, I don’t want to go to the “specialist”. Advise, please, courses on programming for Android, who really studied and tell which teacher really gives knowledge. In the future, I would like to learn programming for iOS, but this is the next step.
Thank you.

Answer 1

It makes sense to use the knowledge that you already have
If you can make sites on js - phonegap, etc.
The disadvantage is insignificant - the loss of efficiency of using the processor five times compared to the same program in C
But this is rarely critical and the power of the processors is growing
Graphics can be accelerated with webgl
In the future in five years, heavy calculations with webcl

Answer 2

Real knowledge and practice can be obtained here:
https://www.udacity.com/course/android-developer-n... (finished)
https://www.udacity.com/course/ios-developer-nanod.. . (going to pass)

Answer 3

In St. Petersburg, there are good courses at Level UP:
1) levelp.ru/courses/mobilnye-tekhnologii/android
2) levelp.ru/courses/mobilnye-tekhnologii/course-deve...