Paul Solt

Creating NSDocument using Folder Bundles and UTI Identifiers

Paul Solt — Fri, 03 Feb 2012 05:04:16 +0000

I’ve been working on a Lion NSDocument-based application that deals with multiple data files. I decided to work with the NSFileWrapper and treat a folder like a single file. (i.e. Xcode Project Files .xcodeproj) I wanted to get an icon to display for the folder and to have it appear as a single file on Finder. In the NSDocument you need to implement the two save/load methods to get started and then you need to edit your Info.plist file.

- (NSFileWrapper *)fileWrapperOfType:(NSString *)typeName

                               error:(NSError *__autoreleasing *)outError {

    // Save data here ...

- (BOOL)readFromFileWrapper:(NSFileWrapper *)fileWrapper

                     ofType:(NSString *)typeName

                      error:(NSError *__autoreleasing *)outError {

    // Load data here ...

Problems

There’s a few gotchas with the .plist file. In order to create a NSDocument using Folder Bundles you’ll need to set the UTI Identifier for the Document Type and the Exported/Imported UTIs. You’ll find this setting on the Info page for your Xcode Target.

My App doesn’t load saved bundles (NSFileWrapper), instead it just looks inside the folder.
I tried to undo the Export UTI by deleting it and remove the Identifier, but that doesn’t help.
By deleting the Identifier I can’t load “New documents”.

Solutions

There are two solutions, the second one is more robust, but the first will get you back to when it was working.

Solution 1: Revert back to Xcode template defaults

Remove all Exported UTIs
Open your App .plist file and remove the LSItemContentTypes from your App .plist file. You can’t see it in the Target -> Info page.
1. NOTE: if you don’t delete an empty LSItemContentTypes array, then you won’t be able to open New files.
2. If LSITemContentTypes is defined, it’ll ignore the “Bundle” checkbox (LSTypeIsPackage) See the Apple docs.
Make sure “Bundle” is checked on the Document Types on your Target’s Info page, or (LSTypeIsPackage on .plist file)
1. This option is magic and auto generates a Identifier for you. (check your save file with “mdls” on the Terminal)
Don’t use an Identifier if you check the Bundle option (Document is distributed as a bundle)
Clean the Xcode project

Solution 2: Use the package UTI

You’ll need to add the correct LSItemContentTypes found in Apple’s documentation. I took a look at the Xcode project file with the Terminal utility “mdls” (See sample output below)

Set a unique identifier (Reverse DNS name) com.Your_Company_Name.Project_Name
1. It needs to match theDocument Type and Exported UTIs
For a bundle, you’ll need to set the “Conforms To” for the Exported UTIs to “com.apple.package”
1. Apple Docs: “A package (that is, a directory presented to the user as a file)”
I noticed Xcode project files also include, public.composite-content
1. Apple Docs: ”Base type for mixed content. For example, a PDF file contains both text and special formatting data”
NOTE: If you mistype com.apple.package, or leave it out, your file folder will be treated like a public.folder, and you’ll get folder behavior.
Clean the Xcode project

Working Icon and Bundle File

If all goes well you’ll now see the Icon (icns) file that you created in the Open dialog and the folder will appear to be a bundle.

Using MDLS to inspect your files

The only way it works as a bundle is if the “com.apple.package” ContentType is listed, otherwise something is wrong. Check your save files with the “mdls” command.

mdls MathAndArt.xcodeproj/

The Potential of Siri

Paul Solt — Tue, 18 Oct 2011 17:48:33 +0000

I’ve been working on iPhone development for several years and I have been very excited to see how the iPhone SDK has progressed. See my original article on how I envisioned the iPad revolutionizing the computing experience. Siri takes the iPhone platform to an entirely new level.

Feature article by MD

If you’re curious as to how the potential of Siri will impact iOS App development, then look no further than the video Apple used to demonstrate the technology, despite its somewhat heavy-on-the-awesome slant. The fact of the matter is, this is voice recognition technology that’s approaching the level of sophistication you saw in Startrek Voyager as a kid, and it could do wonders for 3rd party App developers.

“Load Angry Birds. New game, please. Aim 45 degrees off the starboard. Lower 3 degrees. Fire. Raise 3 degrees. Fire. Down with the piggies! Fire.”

It sounds far fetched, but is it? Voice control to do anything from text messaging to calling, and it’s not difficult to imagine it controlling things that are not traditionally based around natural voice input. It’d also be a great idea to work in some camera/augmented reality games, as playing “I Spy” with Siri could only make the device even more intuitive, when you’re not ringing your husband, friend or O2 without even touching your handset.

An open API to Siri will help push developers in a new direction building innovative software for the iPhone 4S, given that Siri pushes the boundaries in a way that encourages people to try something new. Google Goggles was a great example of this – it took what QR codes were doing and pushed it farther than anyone had expected it to go – I certainly didn’t expect to be able to use my voice to dictate a text message, make two calls and send an email to my boss, did you?

The best thing about it is the potential it awards developers working with voice and hardware interaction, as unless you’re paranoid about SkyNet and HAL-9000 becoming a reality, it certainly puts a friendlier face on an already friendly looking phone. All that’s left is for us to enjoy the adventures many app programmers are embarking on with Siri, in addition to the talented invidiual who’s just ported it to the iPhone 4. Good times to come, ahead.

Photo Table: Sharing Photos on iPad and iPhone using Multi-touch Input

Paul Solt — Fri, 30 Sep 2011 16:47:52 +0000

I’ve been busy avoiding recruiters and graduating to work on a software startup in the RIT Summer Startup Program. Over the past four months we’ve been working out of RIT’s Venture Creations at 125 Tech Park, Rochester, NY. Initially we focused on Artwork Evolution and printing integration, but have shifted directions into supporting photo sharing.

Our new product is called Photo Table. It’s an app that enables sharing photos on iPad and iPhone. The uses multi-touch gestures seen first in my gesture based Wallpaper Evolution app for iPhone and iPad. The interactive Wallpaper Evolution app provided a mechanism to add one photo to the table at a time, but it lacked depth without photo album management. That changes with Photo Table.

Photo Table has been built from the ground up to support image management using the concept of albums. We can import albums from Facebook, Flickr, and the Photo Library. Any image can be added to an album or removed just like you’d expect. Once you have albums you can open them and show family and friends interactive slideshows. All the photos are stored in the app, so we support offline content viewing. We have a lot of fun with the App and are hoping that you’ll be excited to try it.

Website: http://www.PhotoTableApp.com/
Twitter: @PhotoTable
Facebook: http://www.Facebook.com/PhotoTableApp/

Photo Table Facebook Album Importing

http://www.youtube.com/watch?v=7dPguidC6Mk

Add Music to Photo Albums for Sharing with Families

http://www.youtube.com/watch?v=fpge8z65wH4

clang++ is awesome, goodbye g++

Paul Solt — Fri, 09 Sep 2011 22:26:43 +0000

I finally got around to reading up on the clang compiler and I love it. The error messages are so helpful. Here’s a quick example with a syntax error. Lets compile it on the command line.

#include 
int main() {
	std::cotut << "Hello World";
	return 0;
}

What happens when I run the code with g++?

paulsolt@~/dev $ g++ test.cpp
test.cpp: In function ‘int main()’:
test.cpp:3: error: ‘cotut’ is not a member of ‘std’

Here’s what happens in clang++, notice how it highlights the position and it’s actually more helpful in fixing the error.

paulsolt@~/dev $ clang++ test.cpp
test.cpp:4:7: error: no member named 'cotut' in namespace 'std'; did you mean 'cout'?
        std::cotut << "Hello World";
        ~~~~~^~~~~
             cout
/usr/include/c++/4.2.1/iostream:63:18: note: 'cout' declared here
  extern ostream cout;          ///< Linked to standard output

Idea to App Store – How to make, market, and sell your iPhone App

Paul Solt — Tue, 23 Aug 2011 18:53:27 +0000

I’ve posted my presentation from the Computer Science Community at RIT on making iPhone/iPad apps from February 2011. The video is in two parts and I discuss the initial sales, analytics, marketing when releasing an iPhone app.

Update: 8/31/11 Idea to App Store Slides (PDF)

Part 1:

http://www.youtube.com/watch?v=2uza2teEBEQ

Part 2:

http://www.youtube.com/watch?v=iyBis6W28Rw

iOS Development Presentation

Paul Solt — Sun, 12 Jun 2011 14:22:45 +0000

Here are my slides and demo code from the presentation on Friday, June 10th at 10am in ICL5 at RIT.

iPhoneOS Development III – Paul Solt

Gestures Demo

Transparent UITableView with Custom Background UIView and Tap Gestures

Paul Solt — Sat, 14 May 2011 23:38:41 +0000

In order to create a custom background for a transparent UITableView you’ll need to do a few things. I’ve got the basic code below after a lot of tinkering. I’ve also included how to make it so you can hide the UITableView when you tap in the transparent areas below the rows using a UITapGestureRecognizer. In the images below you can see the custom view in action.

: UITableView with Custom Background

Hidden UITableView Showing Custom Background

Key Points:

Don’t subclass UITableView, instead use it as a instance variable in your own custom UIViewController subclass.
Create a custom UIView subclass to use as the background view, this will be visible when the UITableView is hidden or has a transparent background view.
On iPad make sure you clear the UITableView’s backgroundView and set it to nil in addition to setting the background color to[UIColor clearColor]
Register a UITapGestureRecognizer with the viewController’s view and then set the attribute cancelsTouches to NO so that the touches from the gesture propagate to both the UITableView and the custom background view.
In the -(void)handleTapGesture: method you’ll want to send taps that don’t touch a row to toggle the UI so that the UITableView hides or unhides.

Notes:

I show a UINavigationBar, so my UITableView frame needs to take into account the size of the navigation bar.
Set the UILabel’s or custom views backgroundColor in the table’s cells to have [UIColor clearColor] so that they animate and fade correctly.

See the sample code below:

Wallpaper Evolution 1.0.1 Released on the App Store

Paul Solt — Sat, 07 May 2011 02:08:57 +0000

Tap, flick, and zoom psychedelic and abstract wallpapers in a highly interactive photo application. Each image is available in high-definition so that it can be used as a wallpaper for any iPhone, iPod Touch, or iPad using iOS 4.0+.

Limiting UIPinchGestureRecognizer Zoom Levels

Paul Solt — Sun, 27 Mar 2011 01:03:34 +0000

After wasting two days I’ve finally figured out how to correctly limit zoom levels when working with a UIPinchGestureRecognizer. I needed to resize images, but I didn’t want people to go outside of desirable limits.

Here’s the basic math:

1. We know: currentSize * scaleFactor = newSize

2. Clamp the maximum scale factor using the proportion maxScale / currentScale

3. Clamp the minimum scale factor using the proportion minScale / currentScale

The code below assumes there is an instance variable CGFloat lastScale and that a view has been set for the UIPinchGestureRecognizer.

- (void)handlePinchGesture:(UIPinchGestureRecognizer *)gestureRecognizer {
 
if([gestureRecognizer state] == UIGestureRecognizerStateBegan) {
// Reset the last scale, necessary if there are multiple objects with different scales
lastScale = [gestureRecognizer scale];
}
 
if ([gestureRecognizer state] == UIGestureRecognizerStateBegan ||
[gestureRecognizer state] == UIGestureRecognizerStateChanged) {
 
CGFloat currentScale = [[[gestureRecognizer view].layer valueForKeyPath:@"transform.scale"] floatValue];
 
// Constants to adjust the max/min values of zoom
const CGFloat kMaxScale = 2.0;
const CGFloat kMinScale = 1.0;
 
CGFloat newScale = 1 -  (lastScale - [gestureRecognizer scale]); // new scale is in the range (0-1)
newScale = MIN(newScale, kMaxScale / currentScale);
newScale = MAX(newScale, kMinScale / currentScale);
CGAffineTransform transform = CGAffineTransformScale([[gestureRecognizer view] transform], newScale, newScale);
[gestureRecognizer view].transform = transform;
 
lastScale = [gestureRecognizer scale];  // Store the previous scale factor for the next pinch gesture call
}
}

Artwork Evolution 1.2.80 Released!

Paul Solt — Mon, 21 Feb 2011 20:06:51 +0000

Download

Buy Artwork Evolution on the App Store and create wallpapers for iPhone, iPod Touch, and iPad!

New Features

Coffee Table Photos: Touch, slide, and flick photos off the table!
Updated main screen user interface

Video

http://www.youtube.com/watch?v=xkwE8BRQsAo