Solipsism Gradient

Rainer Brockerhoff’s blog

Browsing Posts tagged iPad

Looks like Toshiba has released a device called the Libretto W100:

Compare with this image from the tablet proposal by Mario Amaya and myself (posted August 10th, 2009):

Fun! But I like our hinge better… :-)

While we’re setting out on our vacation in the Central USA, I’ve been thinking about what I should write in a WWDC wrap-up post – and it’s been surprisingly difficult. Update: also read John Gruber’s excellent wrap-up.

As usual, most of the juicy details are under NDA, and I try to be careful with that. Some details about Xcode 4 and LLDB have been published, others have been leaked, and this is indeed the parts I liked most; and I don’t doubt more will be made public Real Soon Now.

I can say some general things about the sessions. While there were relatively few Mac OS X-only sessions – Damien Sorresso’s excellent launchd talk was the one I found most enlightening – to my surprise, there were many sessions that applied both to iPhone OS/iOS 4 and to the Mac. I did audit some non-Mac sessions and most of them were informative and well-presented, and I find myself quite interested in doing an iPad app.

While over 2/3rds of the developers present, supposedly, were doing only iPhone/iPad development and were new to that platform, quite a lot of Mac old-timers were present and I had great fun meeting most of them. I was also gratified to, again, being told several dozen times that someone likes and is using my RBSplitView framework.

As usual, I found San Francisco is a great place to visit – and to eat! Special thanks to Russell of the San Francisco Apple Store for helping me buy my iPad and a brace of accessories, and to all of you – you know who you are – who helped me commemorate my birthday.

Looking back over my WWDC predictions here, I was struck by how boring they were. The same sort of expectations every year, only everything was twice as fast, or large, or whatnot, than the year before. And this year, coming into a conference which is almost completely not about my main platform – the Mac – I noticed I didn’t even have enough information or interest to do the obligatory prediction post.

I was told that over 60% of the developers this year were newbies both to WWDC and to developing for Apple. This seemed, even, a low estimate; I did meet friends from years past, some of them real old-timers, but there weren’t as many as I’d expected – and almost none of the people I didn’t know, that I talked with, were doing anything on the Mac, although some said they’d try to do so sometime in the future.

Indeed, the Mac OS was conspicuous by its almost total absence in the session list, and it was mentioned only offhandedly by Steve Jobs during the keynote – only once, I think. Another, more unexpected, absence from the keynote was the iPad: this, too, was mentioned mainly regarding sales figures, and the rest of the keynote was all about the iPhone 4 and the newly christened iOS 4.

On consideration, however, it makes sense not to talk about the iPad in the keynote: Jobs is notorious for presenting exactly what he wants the press to publish, and distracting them with too many topics is counterproductive. The iPad has had its presentation a few months ago and is selling so well that they’re probably scared that more people will want one; the factories are at max, and cases and other accessories are back-ordered for days or weeks.

Also, an upgrade for the iPad might be a little premature at this point. Any new version would raise protests from those zillions of people that just bought one; the Flash RAM industry is barely keeping up; a faster CPU would need to be dual-core. Regarding the new fancy Retina screen technology, an iPad screen at about 300 dpi would be 2400 by 1800 pixels! I don’t think any mobile video chip can handle that today. iOS 4 is about the only upgrade that’s reasonable to expect to come out quickly.

The iPhone 4 looks good indeed. I don’t need a cellphone myself but the dual cameras and other goodies are tempting; I find myself wishing that Apple would go into digital cameras again. Still, to me, the real star of this WWDC is Xcode 4, the existence of which was also released to the public today; it’s a major step forward, and – as I said several times in the past – many of its features seem to have been enabled by LLVM and its various side projects. One of them, the lldb debugger, is the one I’m particularly interested in; I never liked gdb much.

Many people asked me if I, too, am afraid that Apple will drop the Mac and Mac OS X entirely in the future. Well, I certainly am not! After all, what else would you use to develop for iOS? Xcode 4, for one, seems positively need a 27″ screen for best use – I’m glad I bought a 27″ iMac not too long ago. While the iOS devices might eventually be the tool of choice for consumers to do most of what they on laptops today, laptops will still be useful, and powerful desktops will always be necessary for anything that needs more CPU or graphics power. That said, I can see the laptop line compressing to, say, two models next year, and the Mac Pro going away entirely, or at least replaced by a model seriously more powerful than the high-end iMac.

To close for today, it is safe to say that – without violating any NDA in the process – is that, at least during the next 4 days, whenever any demo hits a glitch, the presenter will ask the audience to turn off its WiFi devices. I saw it happen already, in fact. :-)

While reading the links pertaining to the previous post about a “back” button for the iPad – and, incidentally, for the Mac – it occurred to me that such a capability might be built into a future version of my Klicko utility. Which is Mac-only, of course. For now, Apple doesn’t allow any sort of utilities for the iPhone/iPad, more’s the pity.

I’m rather overloaded at the moment, moving out of my apartment only a few days before going off to WWDC, and I’ve got an iPad app prototype to work on, too; but I’ll definitely look into this as soon as possible. I think that most of the infrastructure, in fact, is already in place inside Klicko.

I did download the Universal Back Button App, but didn’t have time to check out how it works; at any rate, it seems to be quite different in implementation.

Brent Simmons, author of NetNewsWire, writes:

On Macs we have a long-standing culture of apps working together.

On the iPad (and iPhone) we can sort-of do the same thing. We don’t have AppleScript or Apple events, but we do have the URL scheme thing for inter-application communication. It’s technically possible to do some of these same things.

But we don’t have an easy way to get back to the calling app.

What if the calling app added, as a parameter to the URL, a URL to call when the task is completed?

This way the helper app (NetNewsWire in this case) would know, once the task is complete, how to get the user back to their place in the calling app (Twitterrific in this case).

I was thinking about the same issue, coincidentally, and one idea which occurred to me is to use the equivalent of the http referrer URL (often misspelled as “referer” for historical reasons).

For  a standard http request the referrer is the URL of the document containing the clicked link, so you can get back to that document by clicking on your browser’s “back” button. Now, this isn’t really contained in the URL itself – rather, the browser appends this as one of the fields in the http request headers – but the analogy is interesting.

For this to work locally between applications, the referrer URL would need to be set into the URL targeted at the called application. And indeed, there is a -[NSURL setResourceValue:forKey:error:] method that, in theory could add any key/value pair to the URL. (Currently only the “scheme” property seems to be available, though.)

Update: Mike Abdullah points out in the comments that, in practice, this method applies properties to the file a file URL points at, not to the URL itself. Drat.

On the receiving side, the “referrer” value would have to be pulled out from the NSAppleEventDescriptor that the application gets with the ‘GURL’ event.

All this needs filing enhancement requests and Apple would have to do the required twiddling inside their code base – or rather, bases, as this would be useful to have both on the iPhone/iPad and the Mac side. It would take a long time, if it’s done at all.

The alternative would be to developers to, informally, establish a convention for incorporating this into the URL itself. So we’d have something like:
calledscheme:///the/url/parameters&?REF=callingscheme://some/url/to/return

Probably the second part would have to be suitable encoded/escaped, too. Maybe this would be a good topic for discussion at WWDC?

Re: iPad time

1 comment

Interesting piece by Sean Heber aka BigZaphod.  Remember my post about the significance of Clang/LLVM on the iPad?

I think there’s a chance that Apple is slowly building Objective-C into a managed environment similar to Java/.NET. At some point in the future they could define an Objective-C HD (or whatever :P) that no longer maintains total compatibility with C. Since they use LLVM a lot now, they can even use that to analyze your code to make sure that pointer accesses are safe and controlled. Anything that isn’t safely confined to your own app would be an error. Access to the Objective-C runtime functions could possibly even be revoked. After which point, Objective-C HD no longer compiles to machine code but instead to an intermediate representation.

By doing something like this, they can abstract the actual underlying CPU hardware and architecture out of the applications themselves as well as maintain a truly safe sandbox where private and undocumented APIs simply will not be allowed to work. Apps on the App Store would be submitted in this intermediate format which they can translate into the machine code that’s native to whatever CPU happens to be in the device you’re downloading the app for or they could simply put a JIT in iPhoneOS (although there’s no reason to waste the CPU cycles on the device if they can translate them once on the backend – at least for mobile stuff).

Pretty much complementary to my reasoning.

Re: iPad time

No comments

richardl wrote:

Rainer, it is interesting to note that Adobe built their ActionScript/Flash compiler for iPhone on top of LLVM.

http://cs.illinois.edu/news/2009/Oct8-2

http://www.adobe.com/devnet/logged_in/abansod_iphone.html

Thanks, I wasn’t aware of that. However, I don’t think that this invalidates my original argument, which is more based on Clang than on LLVM. Christopher Lloyd also remarked on this:

…Yet Adobe uses llvm for the compiled Flash, so they don’t like Adobe’s parser? silly. http://bit.ly/MQtRZ

Also thanks to Daveed Vandevoorde, who remarked that the LLVM bytecode isn’t as platform-independent as I thought – things like sizes of variables and ABIs (Application Binary Interfaces) stand in the way. Still, it’s not impossible to see Apple defining a generic target platform, in terms of sizes of pointers, integers and so forth, and a specific endianness and runtime ABI, and then staying within the bytecode for that.

Re: iPad time

1 comment

Via John Gruber, I just saw an interesting post by Steve Cheney:

It’s pretty evident that Apple isn’t wed to individual suppliers. Not only are they back to creating their own chips, but they are also one of the only ‘compute’ companies to have used each of the top 3 processor architectures over time – ARM, x86, and Power PC.

…This week Apple confined developers to a specific set of tools (XCode [sic]).

…By telling developers to move to XCode tools, Apple is setting the stage to potentially switch architectures.

…In 2003, Apple advised developers to switch to XCode tools. …2 years later Apple moved to Intel across its entire Mac line.

…perhaps the A4 is NOT an ARM architecture. In fact, it’s highly possible that the A4 is a dual core Power Architecture…

The last sentence is of course false, as Gruber says; the A4 does run ARM code.

While I don’t think that forcing developers to switch to Xcode (which is the correct spelling) means that Apple will soon be switching architectures on their iPad/iPhone line, or on their desktop/laptop line for that matter, Xcode does offer developers a future-proof environment that hasn’t been commented on by other observers: the Clang/LLVM project. Briefly, Clang is a compiler frontend for C-based languages, backed by LLVM – which stands for “Low Level Virtual Machine”. Both projects are heavily backed and staffed by Apple.

Clang has been increasingly supported by Xcode as a substitute for the gcc compiler toolchain. The details are quite esoteric, but one interesting capability is that C-based languages – C, Objective-C and C++ – are compiled to the LLVM bytecode, which is then translated into native machine language by a back-end. The last phase could even happen in a just-in-time fashion, allowing apps to be distributed in LLVM code (therefore running on all current and future Apple machines). Some groups are even working on chips that execute LLVM bytecode directly.

In other words, it’s no coincidence that Apple is now instructing developers to switch to Clang-supported languages and their Clang-wrapping IDE (Xcode). There may not be an architecture switch coming soon, but Apple will have much more freedom in doing their own CPUs for iPad/iPhone, and more ammunition in negotations with Intel and other top-end chip companies.

Photos licensed by Creative Commons license. Unless otherwise noted, content © 2002-2014 by Rainer Brockerhoff. Iravan child theme by Rainer Brockerhoff, based on Arjuna-X, a WordPress Theme by SRS Solutions. jQuery UI based on Aristo.