Ouch, what a step back for Apple.

They clearly are going even further down the path of becoming irrelevant. The writer of this article misses the whole point here. By making it even more proprietary, it hurts Apple long term. Already, Apple products are shrinking dramatically in market share. If Apple makes it even harder to port things to their system or out to other systems, they only increase the chance that they become the "second" system that gets the app, not the first. Apple had 70-80% of the market for a few years, and the development community had to give them first position on everything. Now, they are less than 40% of the tablet market and less than 30% of the smartphone market.

Apple never had 70-80% of the smartphone market. They peaked around 25% worldwide. They're still growing in key markets, pushing as high as 70% in Japan, almost catching up Android in the US.

What Apple has always had is a majority share of mobile development. 95% of mobile software revenues a few years ago, down to around 80% these days.

As the dominant platform for mobile development, the idea that Apple should be making it easier for projects that succeed on their platform to get ported to rival platforms is just plain odd. They want to make development faster, easier, and more powerful on their own platform, and that's exactly what Swift, CloudKit and Metal do. How easy those apps are to port to rival platforms is somebody else's problem.

I never indicated that ios is a cell phone only platform that you seem to imply.  Even though i would argue that they had a much higher percentage of the SMARTPHONE market than 25%.  You seem to be mixing global mobile phone sales with the percentage of the market that Apple was competing in.

I would also like to see what your definition of "80% of mobile development" means.  Are you speaking to the fact that 80% of all apps that are made for mobile are available on the ios platform?  If so, that would only make sense today.  As Apple makes it harder to port programs actually designed for the majority of mobile users, and their marketshare continues to drop, it will reach a point that makes the platform a 2nd tier(like windows phone is today).  Sure the top apps will come, but the other apps will slowly never make it.  This isn't something that will happen overnight, it will happen over years.

All I was saying was that Apple needs to keep the costs to develop for their platform down to ensure that it doesn't become cost prohibitive(WiiU) to release apps on it.

You can argue, but you're going to need to make some pretty bold assertions. Like saying Symbian wasn't a smartphone platform or something:

As for global mobile phone sales, iPhone is still growing by that metric. Getting close to 10% of all phone marketshare.

As for figuring out mobile development share, you're right that it's tricky to quantify. That's why my 80% figure quantified revenues. A nice hard number. I certainly wasn't talking about app numbers, as it's really not fair to give web page wrappers and wallpaper apps equal weight to Microsoft Excel or Pinnacle Studio. Time spent in development would be misleading, since Android development generally takes more time or manpower. Developer interest is one that gets trotted out, but that's like intent to purchase: Measuring wishful thinking rather than concrete action.

All I can say is that people who pay attention to mobile development notice that the best and most important apps tend to be built for iOS first, and other platforms later if at all. Android first happens, but it's less common and doesn't always work out well.

Nothing about Swift makes it harder to port to iOS. Objective-C still works. Xamarin still works. They're just going to be slower to develop and less performant than something built in Swift, giving iOS-first apps an edge. Poor performance is par for the course when you're porting software.

Swift pushes the cost for iOS-only lower, and raises the barrier for porting successful iOS projects to other platforms. If Apple didn't have the developers already, sure they'd want better cross-platform compatibility. Web apps and Java apps were a huge boon to the Mac a decade ago. Now that Apple's in the driver's seat, they want to keep their developers comfortable and make jumping ship less attractive.