Development for os x or ios where is it more reasonable to delve into / start?

Question

iOS

For example, there is an idea for an application, it is planned to develop both on os x and on ios.
1. What do you start with first?
2. Under what is it more logical to study obj-c / swift first of all?

• ios or osx?
  
• Or is it too much for two platforms?
  

3. What is the fundamental difference?
I can imagine how it sounds, but your comments are needed)
Thank you all, and Happy New Year)

Answer 1

iOS and OS X are built on the same platform, the
main difference is UI
1 forget about swift for now
2 check out SI
3 then take a book on Objective-C
4 and then learn Cocoa

Answer 2

Start with iOS specifically on these video tutorials by Alexey Skutarenko https://vk.com/iosdevcourse. There are 50 lessons, homework, a group of almost 4k people. After completing the course, you can get a job. There will also be a Swift marathon in a couple of weeks, but don't even think about Swift yet. First learn Objective-C, following these lessons it will be very easy and pleasant to do it, and then iOS or Mac - you choose for yourself, it will not be difficult to do.
From the bottom video you start and forward to the 50th lesson. https://vk.com/videos-58860049

Answer 3

In a business plan, development for iOS will probably be more profitable than development for os x, so I would advise you to look towards iOS. But as it was rightly noted above, they are built on this basis, so problems with the transition from one platform to another should not cause difficulties.

Answer 4

1) There is no particular difference between ios and os x in terms of development. The program model for these platforms can be absolutely identical. The only thing that can be difficult is programming the user interface. It is better to start, of course, under ios, but at the same time try to do something similar and interesting for osx. It will be useful.
(From my own example: I learned to develop under ios, and decided to write my diploma under os x. I don’t feel any problems or big differences between platforms in terms of development)
2) Objective C.
With swift, in my opinion, it’s still not clear what and how will. Yes, and Objective C will come in handy anyway. If only because all the code that was previously written, for example, various frameworks, they are written in Objective C.