test it to see if it is actually the type of file that its file-name extension claims it is.

This won't work because a file can be a valid file in multiple formats at once and it can also be an invalid file that is nevertheless interpreted as a valid file as well.

Take for example, a plain-text file. Harmless, right? Nope. It can also be a valid HTML file containing executable JavaScript. Or an XML file containing a billion laughs attack.

Or take media type sniffing. Some browsers bend over backwards to interpret crap as HTML even when labelled otherwise by the Content-Type HTTP header. So one attack is to stuff enough HTML into PNG metadata to confuse a browser that doesn't follow the standards into thinking that it's HTML. This is a valid PNG file and anything that checks to see if it's really a PNG file will tell you that much. But it's still not safe.

It's because they are using WKWebView to render web content instead of the newer SafariViewController. SafariViewController requires iOS 9 and Firefox supports iOS 8.

Previously, they did not permit the use of third party libraries in your application; everything had to be built or sourced by you, because there's no intermediate library signing and vetting process that Apple can do on your behalf. They relaxed this when developers screamed like a stuck pig.

This has never been true and the bit about developers screaming like pigs is pure fantasy.

Perhaps you're getting it muddled up with the fact that iOS didn't support dynamically linked libraries? In any case, not many developers cared, we all just used statically linked libraries.

Another site's take was if they couldn't crack it they'd be in line with the FBI for back doors in software.

In that case, the NSA don't ned to crack the crypto, they just need to crack the FBI.

They are so hilariously wrong so often you could build a successful career out of assuming they will be wrong about everything. A selection of their idiocies:

• Apple Should License the Mac to Dell
• Windows Phone to beat iPhone by 2015 (thanks to Nokia)
• Why does the IT industry continue to listen to Gartner?

Sure, if you personally break the law, then you personally are liable.

couldn't you make the case that it was an act of criminal negligence

No. Criminal negligence doesn't simply mean "they did something that upset people". What makes you think they are doing something criminally negligent? What are they negligent of, and what makes it criminal?

I'm sure that this Peeple thing is set up as a corporation, and thus has "limited liability", but in practical terms I'm not sure that phrase really means anything anymore.

Yes, it does. Why would you think otherwise? It's not "a phrase", it's a fundamental part of corporate law.

I can't think of anything in iOS 9 that should have touched code like this, which makes me wonder about the state of source control.

Why? Source control doesn't prevent regressions. Besides, they've clearly been working in this area for iOS 9, see the new network extension points for example.

Apple have had a few regression-type bugs before which again make me think their branching/merging strategies may not quite be up to snuff.

This doesn't even seem remotely related to branching/merging. To be blunt, it sounds like you're just learning source control and are seeing it everywhere.

anyone know of a changed area in iOS 9 that would have necessitated playing with something like this?

Read What's New in iOS. They update it every time they release a new version and it describes what's changed.

You have finally realized that your touchscreen controller actually provides a pressure strength and are able to hype it up like it's revolutionary.

Right now, Apple haven't said a word on the matter, let alone "hyped it up like it's revolutionary". There is zero confirmation from Apple, this is just a blog article based on a rumour.

You fail to understand the difference between a legal principle, such as the First Amendment, and a moral principle, such as Free Speech.

I understand it just fine. The parent commenter does not. He was talking about outlawing the flag.

The First Amendment is a legal enactment of the moral principle.

No, if the First Amendment were a legal enactment of the moral principle you describe, it wouldn't stop at restricting the government's right to curtail speech. It would compel Apple to publish this material. It does not. Ergo, the First Amendment is not a legal enactment of the principle you describe. It doesn't go anywhere near as far.

Apple's suppression of Confederate flag, and Civil War video games, and silly TV shows set in the South, is evil.

Nobody has the right to force Apple to use their resources to publish material that they don't want to publish. And Apple choosing not to publish something is not the same thing as them suppressing it. You want the confederate flag, you can get it from other places. Free speech is not about forcing somebody else to publish your crap.

This is a country founded on the idea of Free Speech.

Your country was founded on the principle that the government should not stop anybody from speaking. It wasn't founded on the principle that corporations must be compelled to distribute other people's material regardless of content. Apple are not obligated to publish this material.

Much better than outlawing their vile ideas

Nobody is outlawing anything. This is an example of a business choosing not to publish something.

They negotiated a deal with the record labels, which the record labels agreed to. That's not sleazy or thieving. If Taylor Swift doesn't like it, her dispute is with her record label that agreed to this deal.

I think you're mixing Apple Music up with Apple News.

Apple hasn't even achieved its primary stated goal of de-fragmenting the music market

Really? You criticise them for it not being a success before they've even launched the damn thing? No other company gets berated for not achieving its goals for a product pre-launch. This is just another of those bizarre articles that holds Apple to not just an unattainable standard, but a standard that doesn't even make sense.

The average iOS user buys far more apps than the average Android user.

Is that actually an important metric?

It is for people who want to sell apps.