MPD » my software

iPhone Reference Errors

Mike — Sat, 28 Feb 2009 16:14:55 +0000

I’ve decided to give iPhone development a try. I have a few ideas for cool mobile apps that I’d love to implement so that I can learn a new platform, a new language, and maybe make some money on the side… However, I’ve remembered what I dislike most about programming – configuration.

I started out trying interface builder and got a basic interface to show up pretty quickly, but it was rather confusing and I didn’t really know what was going on. Next, I thought I should probably just go through the tutorials in my book (iPhone SDK Application Development by O’Reilly) so that I could get an overview of what’s actually possible with the iPhone. That way, when I restart building my own apps it will be much faster because I’ll know what I’m doing.

However, I’ve now been trying to get the TextView example in Chapter 3 (Hello World) to work for almost a week! I typed in all the code correctly (twice, into two separate projects), and it compiles fine, but all I get on the iPhone simulator is a black screen! After a while, I found the debugger console button in XCode and realized I was getting the following errors:

warning: Unable to read symbols for “/System/Library/Frameworks/UIKit.framework/UIKit” (file not found).
warning: Unable to read symbols from “UIKit” (not yet mapped into memory).
warning: Unable to read symbols for “/System/Library/Frameworks/CoreGraphics.framework/CoreGraphics” (file not found).
warning: Unable to read symbols from “CoreGraphics” (not yet mapped into memory).

These frameworks are quite obviously linked in XCode (because the code completion works and the project compiles fine), but for some reason they don’t show up in the simulator. After searching online, I’ve gotten to the point where I think it has to do with the way they’re referenced in XCode and that when running on the simulator, the application doesn’t actually compile all the references together; it just starts running without them, so you have to run it from within XCode. Some people have also said that it had to do with breakpoints in code. However, I’m running from within XCode and I don’t have any breakpoints, so I think it must be a file location configuration issue. Now, I’ve had no luck finding any solutions online or by experimenting…

I’ll let you know how it works out; I’m not going to give up on this.

—- Update – March 1, 2009 —-

Well, the Hello World example started working… First thing to note is that the “file not found” type warnings I noted above don’t actually seem to be related to the problem; now that it works, they still show up.

I fixed the blank black screen by cleaning all targets (in the Build menu), then rewriting Hello World to directly use a TextView instead of manually subclassing UIView myself. Also, I didn’t allocate a window object; I just started using it and let the synthesize keyword work for me (before, I was trying to remove Interface Builder from the project, like it recommended in the book. Here’s the code that first worked (I called the project “Arg” because I was so frustrated):

ArgAppDelegate.h:
#import


@interface ArgAppDelegate : NSObject  {

    UIWindow *window;

	UITextView *textView;

}
@property (nonatomic, retain) IBOutlet UIWindow *window;

@end

ArgAppDelegate.m:
#import #import #import #import "ArgAppDelegate.h"


@implementation ArgAppDelegate
@synthesize window;
- (void) applicationDidFinishLaunching:(UIApplication *)application

{

	CGRect screenBounds = [ [ UIScreen mainScreen ] applicationFrame ];
	textView = [[MainView alloc] initWithFrame:screenBounds];

	[window addSubview:textView];
	[window makeKeyAndVisible];

}

- (void)dealloc { [window release]; [super dealloc]; } @end

This compiled fine and the text view showed up correctly, etc. Next, I slowly changed the code one line at a time back to the original code, compiling at each step, to see if I could find the line that was causing the problem. Unfortunately, I eventually came back to the original code and it worked…

ArgAppDelegate.h:
#import


@interface MainView	: UIView

{

	UITextView *textView;

}
@end
@interface ArgAppDelegate : NSObject  {

    UIWindow *window;

	MainView *myMainView;

}
@property (nonatomic, retain) IBOutlet UIWindow *window;

@end

ArgAppDelegate.m:

#import #import #import #import "ArgAppDelegate.h"


@implementation MainView
- (id)initWithFrame:(CGRect) rect {

	self = [ super initWithFrame: rect ];
	if (self != nil) {

		textView = [ [ UITextView alloc] initWithFrame: rect ];

		textView.text = @"Hello, World!";
		[self addSubview:textView];

	}
	return self;

}
- (void)dealloc {

	[ textView release ];

	[ super dealloc ];

}
@end
@implementation ArgAppDelegate
@synthesize window;
- (void)applicationDidFinishLaunching:(UIApplication *)application {

	CGRect screenBounds = [ [ UIScreen mainScreen ] applicationFrame ];

	CGRect windowBounds = screenBounds;

	windowBounds.origin.y = 0.0;
	self.window = [ [ [ UIWindow alloc ] initWithFrame: screenBounds ]

		autorelease

				   ];
	myMainView = [ [ MainView alloc ] initWithFrame: windowBounds ];

	[window addSubview:myMainView];

    // Override point for customization after application launch

    [window makeKeyAndVisible];

}

- (void)dealloc { [myMainView release]; [window release]; [super dealloc]; }

main.m:

#import


int main(int argc, char *argv[]) {

NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; int retVal = UIApplicationMain(argc, argv, nil, @"ArgAppDelegate"); [pool release]; return retVal; }

I hope this helps somewhat to anyone having the same problem. I found this incredibly frustrating and am not entirely happy about my solution here. I still don’t really know why it happened in the first place, so I’m worried it will come up again in the future. Let’s hope not!

Dancing for Engineers

Mike — Mon, 07 Jan 2008 04:51:07 +0000

Now here’s a topic I’ve been thinking about for a while. I started going to salsa dancing lessons fairly regularly this fall, but am having a hard time remembering the long sequences of complex moves that I learn in the MIT lessons (which are great, by the way). Even when I can remember them, it’s hard to do them on the dance floor with a girl who doesn’t also know what is coming, while staying on the beat, etc. etc. So, at some point this fall, I thought to myself that there must be a better way to learn enough sequences of moves not to bore a good follower to tears.

As I thought about the problem, I realized that salsa dancing (and most partner dances) is really a finite-state machine. We have X number of states (the positions that you end up in on beat 1), and transitions between the states (twirls, etc.). Naturally, I thought of creating a diagram with states and transitions and tracing paths through the diagram to come up with new sequences. This way, if I could memorize a few positions and all the different transitions between them, I could come up with lots of sequences on my own without ever having to memorize a two-minute series of steps. Each set of steps would be at most 8 or 16 beats long.

Still, I didn’t know exactly what to call each state, what precisely is considered a transition, or most importantly, how to present this information in a usable manner. Last week, I was again thinking about this and realized that since a finite-state diagram is also a directed graph, and the web is a directed graph, a webpage made perfect sense for a presentation mechanism. Moreover, if I used a wiki, I could start adding pieces very easily, even if I don’t know the best terminology or have the perfect definition of each state. Plus, other people can add their own moves to the wiki and eventually, we can all learn from each other.

Thus, yesterday morning, I started a new website: salsa.wikidot.com. So far it’s not much; I have a few positions and moves described, and I plan to add more. I feel a little bit like I shouldn’t actually be the one adding content, since I’m so new at dancing and don’t really know how to describe everything. However, I also think that a lot of times we just need to start doing something even if we don’t know how, so there it is. I have it set up so that it will be easy to add photos and videos of the steps if I ever get that far. Should be fun. Hopefully this helps someone someday.

MIT Undergraduate Advanced Project – Complete

Mike — Sat, 02 Jun 2007 14:06:38 +0000

Near the end of my UAP, I promised my adviser that I would release the code I wrote as Open Source, so that people could continue to work on it after I left. If you’d like to try out my system or just take a look, it’s at http://daugherty.mit.edu/StoryAde1.0/Documentation.html.

MIT Undergraduate Advanced Project

Mike — Sun, 20 May 2007 04:09:36 +0000

As of Friday, I am done with every requirement for an undergraduate degree in computer science from MIT, except for one not-too-troublesome final! I had quite a time trying to get my UAP (senior project and write-up) finished on time… Which didn’t quite happen. However, I talked to Anne Hunter (course administrator) and received permission to turn it in one day late, which gave me just enough time to go through another revision with my great adviser, Barbara Barry.

My project ended up being some work in story-analysis using common sense (provided by ConceptNet, another Media Lab project) as well as trying a new approach to anaphora resolution (basically determining antecedents for pronouns), which didn’t rely so much on common sense.

If you’re really interested, you can download the paper I wrote. I also am planning on releasing the source code to my project by the end of the month, though I want to get through my linear-algebra final first before I clean it up and put it on a webpage somewhere.

More Map updates

Mike — Sat, 12 Aug 2006 14:07:00 +0000

I spent some time this morning to create a generic page in which people can enter a flickr username and set name, and it will generate a timeline map for them. Check it out at http://web.mit.edu/mpdaugh/www/maps/mapPage.html. It currently does no input validation, so be sure to type your username and set names correctly!

Photo Page update

Mike — Sun, 30 Jul 2006 01:15:00 +0000

Today I was kind of a lazy day for me… I slept in, then just hung out for a while. I made some phone calls to friends, cooked food for the next few days, etc. I also got a chance to work on my image map again. I cleaned up some of the code by putting it into an object in a separate .js file. I also added a timeline background and changed the slider image. I think it looks a lot better now. Check it out at: http://web.mit.edu/mpdaugh/www/maps/photoMap.html?set=72157594201283566

As usual, let me know what you think. I know the timeline is a little off and the slider has a few quirks as well; I’m working on polishing them up.

Also, if you are trying to few the site in IE and it doesn’t work, let me know. I don’t have a computer that can run IE handy, so I’m having trouble debugging it. Right now the site will probably only work in FireFox.

Minnesota Tomorrow

Mike — Tue, 18 Jul 2006 01:52:00 +0000

Tomorrow, Thomson West is flying me out to Minnesota, where I will be visiting with Ken Ross, etc. through Friday. I’m excited because this is my first business trip ever.

Tonight, I also wanted to mention that I’ve worked a little bit more on my map. After some trouble getting the Flickr REST API working because I didn’t realize that cross-domain xmlhttp requests were not possible, I finally have the site set up so that the photos come from a specified photoset on Flickr. For example, the set that I have summer pictures in is 72157594201283566, so the url you would use to see these on a map is:

http://web.mit.edu/mpdaugh/www/maps/mapPage.html?set=72157594201283566

To see other photosets mapped this way, just replace the number at the end of the url with the set id of your desired set. In order for my application to map the photos, though, they must be geotagged. This means that they must have two tags, one starting with “geo:lat=” and the other starting with “geo:lon=”. Check out one of my photos in the set Summer06 for an example.

Right now, the time scale on the bottom only goes from June-August of this year, but I plan on having it dynamically rescale based on the time of the photos in the input set.

In any case, I probably won’t be able to work on this until next weekend, so let me know if you think it’s interesting, and if so what features you’d like to see. Thanks for your feedback!

Online Again

Mike — Sun, 16 Jul 2006 13:40:00 +0000

As I mentioned in my last post, we’ve had more trouble with our internet connection here… We tried for a while to get the router to work again, but it wasn’t a quick fix. Then, I didn’t take time to work on the problem again for a while because I became pretty busy. Let me explain…

Steph has built up some vacation time over the last year, so she decided to come and visit San Jose for a week before spending the Fourth of July weekend with my in Las Vegas.

A few days after she went back home, my family came to visit for a week, so then I spent my time not at work with them.

They just left yesterday, and since then I’ve started to work on a little project visualizing all the photos that I’ve taken over the last few weeks. Check it out here (I can’t promise that it will be working when you look at it, since it’s still under construction): Mike’s Map

To use, drag the slider (the blue icon at the bottom of the page) to the right. As you move, you will see the current date range change and any photos taken within that range will show up on the map.

It’s such a beautiful day out right now, though, that I think I’m going to stop writing so I can go out and enjoy it. I’ll write more later.