Quick and dirty notes on an excellent panel.
Joshua Siler,
babcock jenkins VP of Tech, web developer
Jordon Lev, senior developer
[I know some of this stuff already, comments from me are in
brackets]
They do relationship marketing for sun, linkedin, intel, IBM,
business to business in general. They are interested in metrics
and so on
So they did an iPhone app related to that
I am surrounded by netbooks
"web developers are mad for power." Because we're used to
insanely lazy tools that can casually abuse database servers and
application servers and the desktop CPU and it all works anyway.
The iPhone does not work that way.
400mhz processor, 128mb RAM, 10 to 100 times slower than a
powermac G5. "Premature optimization" is not so bad in this
environment. You can't process 5 megs of XML and turn them into
a graphics display on the fly. [This is why Objective C is more
appropriate than JavaScript and Canvas if you want any speed]
People expect immediacy on iPhones. The latency of web pages is
something people are conditioned to only for web pages. Also the
browser displays that it is still loading stuff in multiple
ways. iPhone app developers are responsible for doing that on
their own.
Slow stuff should be asynchronous where possible (but remember
that this can lead to a lot of confusion if it's poorly done).
Objective C is not in the top 20 programming languages based on
search results. It's all the way down at #2, behind COBOL and
FoxPro and Ada etc. It's just barely more widely discussed than
Scratch or Haskell.
Objective C means you're dealing with pointers and memory
management (without garbage collection- it's up to you to free
things you don't need anymore, and not free them twice).
Multithreaded code is common (PHP doesn't have threads). As for
the syntax... he refers to it as "syntactic saltiness" rather
than "syntactic sugar."
[Why can't Java source, or almost-Java source, be compiled to
Objective C source and so on? Could a subset of PHP be compiled
to Objective C, creating a new audience of programmers? Did I
sign away the right to even try to create something like that?]
Xcode is the development environment, practically speaking,
period the end. You could edit your source in Textmate and
switch back and forth maybe.
Cocoa, on the other hand, is modern and nifty and generally not
an experience you'll hate. High end UI controls can be dragged
and dropped into the application' UI and they will scroll and
bounce and do all that stuff on their own. You populate them
with data and go on with your life.
iPhone 3.0 OS will of course make all of this obsolete next
week... well not very... but the preview means it'll be a more
serious change perhaps than previously
[Apparently I'm legal if I seek to create a compiler from
something friendlier to Objective C. Interpreters are forbidden.]
Data connection is flaky. [What does that mean? Lost packets in
the middle of documents = not normally possible with TCP, it
just dies outright. I assume they mean connections dying halfway etc., which is possible in TCP]
REST, with JSON responses from the server, is vastly more
efficient than SOAP and other heavy XML stuff and they like it
for devices like the iPhone. And it just so happens I made
exactly the same choice for pkMediaPlugin's API because of the
simplicity of it all.
What are they using to parse JSON in Objective C?
Cocoa is big on events and delegates... message passing is used
to communicate between objects. Rather than calling something
and waiting for completion, you are more likely to receive a
message when the work is done.
Interface Builder places text boxes, buttons, etc. on the screen
in a friendly way, but the code to make them do anything is up
to you.
You can create multiple "views" (distinct screens / pages of the
application's interface) and use buttons to swap between them.
The app delegate class is the "main function" or "master
controller" of your application.
We use @synthesize rather than `new'.
The RootViewController corresponds to the default view, you can
add more views and you often build your app out of a few views
[Not sure why "model" and "view" classes have names like
"WebsitesDataController" and "SettingsViewController". Is this
their own private convention? It's weird.]
[Here's a json library for objective c:
json-framework ]
They used
SBJSON instead.
return [jsonParser objectWithString:jsonString error:NULL];
Why didn't they do this as an iphone-safari web application?
Response time (JavaScript is certainly slower than Objective C)?
Their answer: users like apps. [Also an app ought to be faster because compilation/interpretation of JS and HTML and CSS is not required.]
[UIAlertView openURLAlert = [[UIALertView alloc]
initWithTitle:@"Connection Error"... ]
[openURLAlert show];
/* Forgetting this would be Bad; we have to manage stuff
ourselves */
[openURLAlert release];
You write a cellForRowAtIndexPath method for your table view and
bam, Cocoa starts calling that to get content for that cell when
it's visible etc.
[Ask them to elaborate on "autoreleasing" things... I did, see the end]
// alloc allocates a raw object, init is what we think of as a
constructor
// settingsController is a pointer
SettingsDataController = *settingsController =
[[SettingsDataController alloc] init];
// Now we give those resources back
[settingsController release]
* * *
They like:
Exciting platform
Standardized hardware
Cocoa and MVC
Bare metal programming is kind of exciting for a change
They don't like:
Objective C
Refactoring is hard. Objective C just doesn't accommodate DRY
very well
(of course, PHP is not totally great that way either, he's used
to Ruby)
Lots of assumed knowledge and undocumented stuff
Xcode is crude
App deployment is a pain
Flaky connectivity
Apple controls the universe
[These guys are not the most experienced iphone developers in
the world, but they are smart and successful and have a valuable
perspective similar to our own... very similar to what ours
would be minus my past C/C++ experience]
[I asked about autorelease and memory pools as an alternative to
alloc/release. They don't really know the answer to that one. However:
http://www.cocoadev.com/index.pl?AutoRelease ]
