CoreData + iCloud, Buyer Beware

February 4th, 2013

Back when iOS 5 was released, it was introduced having support for Apple’s new “cloud service”, iCloud. Dutifully, Apple provided developers with an API to store and access data in iCloud, and their usual Apple way, attempt to implement the “heavy lifting”.

We can now store small bits of key-value data, quickly and easily, to be shared amongst our devices.

Additionally, documents can be “magically” store with minimal additional effort from previous document support.

Finally, the coup-de-gras, is the ability to sync our Core-Data backed data, again, with only the smallest number of changes to current implementation.

To help its developers along, Apple provides sample projects and code snippets to demonstrate the ease by which these magical technologies may be easily incorporated.

Even at the latest local CocoaHeads meeting, the presenter puts together a demo that shows the wonders of using CoreData plus iCloud, and we all applaud in approval.

Others might have disagreed, however.

  • No Identity apps had their tush bitten by a released application.
  • Notable Mac developer, Bare Bones Software (at this time) is still struggling with getting their app, Yojimbo, to play nice with iCloud (although, in all honesty, they might have come from a slightly different direction with converting the now defunct MobileMe support to iCloud)

Not trying to be a nay-sayer, but this is not comprehensive list of complaints we have heard. We haven’t made the transition on Wooly Tasks yet, so we are not speaking from first-hand knowledge, but best to go into the effort with eyes-wide open.

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OpenGL glTexParameters

August 22nd, 2012

Silly me, I thought that whenever you bind a texture for rendering, you need to set the texture parameters at that time. Through a bit of trial and error, and a lot of reading, unless there is a need to change the texture parameters during runtime, you can set them once and forget about them at initial texture loading to the GPU. As long as this texture is valid (not been deleted by glDeleteTextures(…)), then these parameters will remain valid and associated with this texture. Of course, loading of textures should ideally be done once, at the start of the application or game’s level.

// allocate a new texture, bind it and set the initial parameters
GLuint name = 0;
glGenTextures(1,&name);
glBindTexture(GL_TEXTURE_2D,name);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
// set other texture parameters
...
// load our texture data
glTexImage2D(GL_TEXTURE_2D,...);

 

Now, when we want to render our quads (double triangle strips), we just bind our texture (assuming that textureID is value obtained from the code snippet above and saved someplace logical).

glBindTexture(GL_TEXTURE_2D,textureID);

And submit our quad information

GLfloat verticies[8] = {...}; // 4 x,y pairs
GLfloat texCoords[8] = {...}; // 4 s,t pairs
GLubyte colors[32] = {...}; // 4 r,g,b,a quartets
glVertexPointer(2,GL_FLOAT,0,verticies);
glTexCoordPointer(2,GL_FLOAT,0,texCoords);
glColorPointer(4,GL_UBYTE,0,colors);
glDrawArrays(GL_TRIANGLE_STRIP,0,4);

The less OpenGL calls you need to perform, the better your game’s performance will be. Hopefully this bit of information will help.

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NSDates and Fractional Seconds

July 18th, 2012

A recent overhaul to Wooly Tasks allowed me to manage and query for Task records quicker, more easily, and more reliably. However, I quickly ran into a silly snap when ordering lists of Tasks based on their due dates.

Would you care for another date?…

The recommended method for adding time to a NSDate is by setting up a NSDateComponents object and adding the components to the date object that you want to change. Behind the scenes, the OS will handle the cases of Daylight Savings time changes and Leap Years correctly. Simply adding a NSTimeInterval does not.

Incorrect:

NSTimeInterval oneHour = 3600; // magic number! 60 seconds * 60 minutes
NSDate *newDate = [date dateByAddingTimeInterval:oneHour];

Correct:

NSDateComponents *components = [NSDateComponents new];
[dateComponents setHour:1];
NSDate *newDate = [[NSCalendar currentCalendar] dateByAddingComponents:components toDate:date options:0];

The NSDateComponents class interface for setting the hour uses a NSInteger, and not a float or double. This is true of all the other components:

...
- (void)setDay:(NSInteger)v;
- (void)setHour:(NSInteger)v;
- (void)setMinute:(NSInteger)v;
...

Dates gone bad…

OK, now we know the correct way to add time to a date, let’s look at something that could bite us in the ass. In the case of Wooly Tasks, we limit due dates to have granularity of every 5 minutes. We also prepopulate a new task with a date that falls on the hour, and is at least 30 minutes from the moment the task was created. So if the current time is 12:34 when we create the task, then we’ll choose 2:00 instead of 1:00 as the due date time. We call this normalizing the due date.

The problem exists, if we create a couple of tasks and normalize the date something like:

NSDate *date = [NSDate date];
NSUInteger unitFlags = NSMinuteCalendarUnit+NSSecondCalenderUnit;
NSDateComponents *components = [[NSCalendar currentCalender] components:unitFlags fromDate:date];
NSInteger hour = ([components minute]<30) ? 1 : 2;
[components setHour:hour];
[components setMinute:-[components minute]];
[components setSecond:-[components second]];
date = [[NSCalendar currentCalendar] dateByAddingComponents:components toDate:date options:0];

This will wind the minutes and seconds back to hh:00:00, and the hour ahead by one (two if the date was less than 30 minutes from the next whole hour). Unless you examine the actual NSTimeInterval of these dates, then several created within a short period of time (for our example, within 5.5 seconds of each other) that might appear to be the same time:

Date 1:

July 18, 2012 4:31:39 PM PDT
364347099.942335
July 18, 2012 6:00:00 PM PDT
364352400.942335

Date 2:

July 18, 2012 4:31:45 PM PDT
364347105.456080
July 18, 2012 6:00:00 PM PDT
364352400.456080

Each date above is shown with four values: the raw date, the raw date in seconds*, the normalized date, and the normalized date in seconds*. (* number of seconds since January 1st, 2001 GMT). What you notice is that the seconds display have a fractional part that doesn’t get reflected by the user readable display.

This becomes problematic in applications that want to sort records by dates as the primary sort key, and another criteria for a secondary sort key. Particularly so when the coarseness of the dates is less than at the seconds level. For instance, if we sorted the above normalized dates, then record with Date 2 would appear before record with Date 1, even though to the user they would appear to be the same. In cases where the secondary sort criteria would have put a record with Date 1 before Date 2, this sorting would have failed to do so.

A Good Date…

There is no way to remove these fractional seconds by using -dateByAddingComponents:toDate:options: because -setMinute:, as noted above, accepts a NSInteger and not a floating point value type. We can easily modify our code above to handle that using our handy-dandy function, trunc():

NSDate *date = [NSDate date];
NSTimeInterval seconds = trunc([date timeIntervalSinceReferenceDate]);
date = [NSDate dateWithTimeIntervalSinceReferenceDate:seconds];
NSUInteger unitFlags = NSMinuteCalendarUnit+NSSecondCalenderUnit;
NSDateComponents *components = [[NSCalendar currentCalender] components:unitFlags fromDate:date];
NSInteger hour = ([components minute]<30) ? 1 : 2;
[components setHour:hour];
[components setMinute:-[components minute]];
[components setSecond:-[components second]];
date = [[NSCalendar currentCalendar] dateByAddingComponents:components toDate:date options:0];

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Posted in iOS, Mac OS, Objective-C | Comments Off

An ARC Transition Tale

July 10th, 2012

If you are not a software developer, this post will probably of less interest to you. Otherwise, please read on…

Recently, I updated Wooly Tasks to use Automated Reference Counting (ARC). The transition from a non-ARC project to an ARC project is fairly straight forward, and mostly automated by Xcode 4. ARC allows the developer to worry less about Cocoa memory management rules, and instead focus on their object graphs and creating great software. ARC is a handy tool, but you now a have some new rules to learn (although, in truth they are probably less confusing as a whole than the old rules). One that is important is object lifespans. Essentially, this means the LLVM compiler can decide to release an object that it deems unused at any moment within the body of the code. We’ll see what kind of ramifications that presents soon.

It’s all fun and games until you shoot your eye out…

Once I had successfully transition (i.e. it compiled and linked), I tested Wooly Tasks using the simulator. To my delight, everything still worked as expected. OK, time to build and install on a device (in this case my iPhone 4S running iOS 5.1).

Launch.

Boom!

Crash. What the #^$#!!

Check with the Simulator again. Fine.

Back to the iPhone. Crash. Gah.

Unfortunately, it crashes due to an autorelease object, so there is no stack dump to figure out what the object is that is causing the issue (this is not entirely true, you can look at the crash log in Xcode, and this would give you plenty of clues…I didn’t think to look there first, unfortunately — lesson learned). All I get is a cryptic console log exception message stating:

“[Not A Type isEqual:] sent to deallocated object 0x….”

Well, huh.

Debugger spelunking time.

So, I started running it in the debugger and setting breakpoints starting from the first UIApplication delegate call and on down the line until I narrow it down to the setting up of the first view controller and displaying its view. Eventually I found the offending code (for brevity, I have left out the values, they were irrelevant to the issue, as is the particular color creation method):

CGColorRef color = [[UIColor colorWithHue:saturation:brightness:alpha:] CGColor];
self.layer.shadowColor = color;

Do you see the problem? Clang’s document on Automatic Reference Counting and lifetime semantics states:

By default, local variables of automatic storage duration do not have precise lifetime semantics. Such objects are simply strong references which hold values of retainable object pointer type, and these values are still fully subject to the optimizations on values under local control.

We have done the equivalent of:

UIColor *uiColor = [UIColor colorWithHue:saturation:brightness:alpha:];
CGColorRef cgColor = [uiColor CGColor];
self.layer.shadowColor = cgColor;

LLVM has every right to deallocate the UIColor object immediately after obtaining the CGColorRef from it, since by all accounts, it is no longer be used. This would then invalidate the data referenced by the cgColor local variable. When we set the shadowColor for the layer, we are potentially (in this case, we definitely were) stuffing an invalidated (but not nil’d) object value into it.

The Fix

The simplest solution was to rewrite the code like:

UIColor *color = [UIColor colorWithHue:saturation:brightness:alpha:];
self.layer.shadowColor = [color CGColor];
LLVM compiler will not be able to insert a release between accessing the CGColor and assigning it to the shadowColor.
And here you thought you could forget all those pesky memory rules.

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iOS: UIMenuController

June 12th, 2012

File this one under: For my own future reference.

UIMenuController was introduced as public API in iOS 3.0 (along with UIPasteboard and Copy and Paste functionality). This is now a technology we take for granted in the iOS world, but it really wasn’t that long ago that Apple hadn’t provided this seemingly basic service.

Recently I was using this API in DeepDish GigBook to update some fairly crufty workflow. I am not going to explain how to use UIMenuController, as the documentation is fairly straight forward. What I will mention is a few “gotchas”.

1. There is no target for an UIMenuItem.

It is whomever is the First Responder. In other words, your controller class probably (in most cases) is what will handle the actions, so you want to make sure it can become the first responder. Add the following to your controller implementation:

- (BOOL)canBecomeFirstReponder
{
    return YES;
}

IF you don’t do this, then passing the message -setMenuVisible:animated: to the UIMenuController will have no effect.

2. Implement - (BOOL)canPerformAction:(SEL) sender:(id) in your controller:

There is little reason not to, and many reason why you should. This will be implemented in the same controller that also implemented -canBecomeFirstResponder. This will allow you to enable or disable (effectively hiding) any menu options you may or may not want at any particular time. It avoids having to recreate the menu items list every time the user invokes your menu through whatever gesture.

- (BOOL)canPerformAction:(SEL)action sender:(id)sender
{
    if ( action == @selector(myMenuItemMethod:) ) {
        return YES;
    }
    else if (...) {
        return ...;
    }
    else {
        return [super canPerformAction:action sender:sender];
    }
}

Of course, there might be situations where the same view might support different menu configurations depending on some context, in which case you probably do need to rebuild the menu list each time. But in case where you don’t…

3. Remember that your menu items are persistent:

Whatever menu items you add will remain there until they are set again. If you think about it, this makes sense since UIMenuController is a singleton.

This one bit me due to two reasons. 1) I didn’t have -canPerformAction:sender: implemented, 2) I assumed that menu items list must be rebuilt prior to each invocation of the menu. What happened was a different subview was presented within the main view of the controller, and the subview contained an UITextView. When the user double tapped the text view, and had some text on their pasteboard, the Paste menu option was displayed, along with the other menu options already installed by an earlier menu displayed in the same view. Oops.

The first solution was to nil out the menuItems when the menu was dismissed. This seemed a bit of hack. The better solution was to follow item 2 above since my menu items never changed as long as I was in this particular view. In this case, since a subview only required the basic Copy, Cut, Paste, Select, Select All, etc. the controller would return NO when the controller itself was no longer the first responder. Revisiting our implementation of -canPerformAction:sender: from above:

- (BOOL)canPerformAction:(SEL)action sender:(id)sender
{
    if ( action == @selector(myMenuItemMethod:) ) {
        return [self isFirstResponder];
    }
    else if (...) {
        return ...;
    }
    else {
        return [super canPerformAction:action sender:sender];
    }
}

Cheers!

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Posted in Design, iOS, iPad, iPhone, Objective-C | Comments Off

What’s Happening

June 6th, 2012

It’s been quiet on the Wooly Blog front. Too quiet.

To be honest, it is because we spend our days writing code and not writing prose. But, communication is key, and everybody wants to know their favorite Wooly company is still alive and kicking.

We have noticed that Wooly Tasks is a bit long for an update. All I can say is that a pretty nice update is in the works. What to expect:

  • New task management engine to more efficiently and reliably track and manage the tasks.
  • Printing and Twitter support (paid version only)
  • New UI layout to show the most important information quickly, and additional details when you desire them.
  • On iPad, removed hideous paper pad background. It wasn’t our finest moment.
  • iCloud integration and synching between devices (paid version only).
  • Stability enhancements (ok, we fixed some bugs).

On the Wooly Wind Chill side of things, we are looking into being able to integrate your favorite weather source for tapping into current temperatures and wind speeds. The first version will roll out with just a couple, and subsequent versions will add more.

On the contracting front. We are still helping Deep Dish Designs make their wonderful iPad Music application, DeepDish GigBook. While we can’t state specifics, we do know a new version with some very useful enhancements (do we sound a bit biased?) that both companies worked hard on putting together will come out “soon”. Current shipping version in the App Store is 1.6.2, so when you see a version number greater than that, then that “soon” time has arrived.

Speaking of iOS contracting services. If you have a funded product idea that you want Wooly Beast Software to help you bring to market, please feel free to contact us at info@woolybeastsoftware.com.

Finally, after considerable discussions with management, we have embarked on an exciting new project. In this post, we will not go into a lot of details of what it is, because there are still some things to work out at our end. However, we can say it will involve a bit of this: 

and this:   

and a whole lot of these guys:

That’s about it for now. Next installment we’ll discuss a bit more on what’s going on with our new project, and chronicle the steps up to release.

 

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Xcode 4: Renaming projects

January 22nd, 2012

Xcode 4.x is a great leap forward for iOS and Mac OS Developers. Many thanks should be expressed to Apple and its engineers for their hard work in putting together such a toolset. If you were used to Xcode 3.x’s way of doing things, then you might find yourself wondering how to do various operations that seemed to have disappeared. Renaming a project one such feature that took a while to relocate, so I am sharing how it is done in Xcode 4.x. It is much better to rename the project through the mechanism provided by Xcode than trying to rename the project file via the Finder. I have done so in the past, and it wrecks havoc on the project settings.

 

Step 1. Select the project in the Navigator (left side of Workspace. Command-1 to reveal).

 

 

 

Step 2. Make sure the File Inspector is visible. (right side of Workspace. Command-Option-1 to reveal, or third most button in the view button cluster).

 

Step 3. Under Identity, you will see the Project Name text field.

Change the name of the project to the new desired name.

A drop down sheet will appear when you exit the text field. It will be showing you what will change, giving you one last chance to back out…sort of. This last chance inquiry is for settings that are derived from the project’s name (target name, product name, prefix header, etc.).

If you say “Don’t Rename”, the project itself will still be renamed, but the auxiliary portions won’t. This could potentially leave things in an unsavory state. I imagine this is a bug, and as a matter of fact, even had Xcode crash more than once when testing out renaming of the project, but not going through with it.

You may also be asked whether you want to take a Snapshot prior to preforming the renaming. This is entirely up to you and your risk tolerance.


That about covers it. Happy programming!

 

 

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Steve Jobs 1955-2011

October 5th, 2011

Steven Paul Jobs 1955-2011

Today, Steve Jobs, an amazing man in his own right, and an undisputed visionary, passed away at age 56. He led an amazing life, did amazing things, and created several amazing companies (NeXT, Pixar, Apple). He, more than many others in history, has done more to positively influence people’s lives and livelihoods.

I am selfishly sadden that I never got to personally meet Steve, even though I have admired him ever since I brought home my first Apple product, an Apple ][+, nearly 30 years ago. That purchase, earned by a summer of construction work during the summer between my sophomore and junior year of high school, led me to the path of developing software as a profession.

When I lived and worked in Sunnyvale, in the early 1990's, I use to ride my bicycle up Foothill Expressway and into Palo Alto (usually stopping at Stanford with a book to read and soak in some of the sun). Often, before heading home, I would ride into the neighborhoods of Palo Alto, knowing that Steve Jobs had his house somewhere there. I was hoping that I might have a chance encounter with him, or at least see his house from the street. I never did, and having seen pictures of his house, I'm pretty sure I was in the wrong neighborhoods, but it sure was fun trying at the time.

Other people who may or may not have made their marks on the world, including noted civil rights leader Rev. Fred L Shuttlesworth, died on the same day. This doesn't mean that Steve was better than these other people. We could all learn from their lives. Steve gave us the gift of showing that hard work, breaking the status quo, and doing things a bit differently is a Good Thing.

May his family find comfort somehow in knowing he is no longer suffering, and is at peace. May the world come together and embrace his propensity of creative thinking and attention to detail.

Rest In Peace, Steve. You inspired me for 30 years, now we continue forth and carry your message into the future.

 

“Stay Hungry, Stay Foolish”

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WWDC 2011 Keynote

June 6th, 2011

No, I’m not there. :-( As of the time of this writing (9:30am WWDC time), the energy is palatable for this year’s event even 600 miles north of San Francisco (one of my all time favorite places to be) up in Portland.

We already know that Lion (Mac OS X 10.7) will be “announced” (it already really has been, just not the minutia), iOS 5 (same…it exists, no real details), and iCloud (more heavily covered…ie streaming music and a music locker, but free MobileMe services too?). What we don’t yet know is what the “Just one more thing…” is all about.

We know there is something afoot due to this image taken inside Moscone West this morning: (image no longer available)

I originally speculated with @CocoaGeek that this might just be the banners seen already that read “Lion + iOS 5 + iCloud = WWDC11″. However, as @CocoaGeek correctly pointed out to me, this doesn’t make a lot of sense since those have already been announced, even if no details have been given.

So, at 10:00 am (WWDC time) we’ll begin to know that all this is about. All I know is that 2011/2012 is going to be very, very good years to be an Apple developer.

Will update as more information flows in….

10:00 am update…

Mac OS X Lion “announced’ along with 10 new features (out of a claimed 250) being showcased:

  1. Multitouch gestures with trackpads
  2. Full screen apps (meant for smaller screen laptops/devices)
  3. Mission Control (kind of like Exposé + Spaces). A simple gesture gives you a bird’s eye view of everything on your system.
  4. Missed this one…will add it once I can get the skinny on it. Ah, I guess it was the Mac App Store. Nothing terribly new, other than it has become the number one channel for buying PC software.
  5. Launchpad, a new launcher a’la iOS Springboard for the Mac OS. Apparently also employs a sandboxing scheme.
  6. Resume (Nice!) allows you to return to the exact state of the app and its documents
  7. Auto Save (enough said)
  8. Versions… version control for everyone (I wonder if it is based on Git? :-) ). Time Machine for all your documents. Who doesn’t want/need that?
  9. AirDrop (Yes!) peer-to-peer WiFi based network (what?! No bluetooth love!?)
  10. Mail.app with updated UI and other enhancements.

Available only via the Mac App Store, and only $29.99!! Wow!

10:34 am update…

OK, that’s the 10 features they chose to show-case. Looking forward to hearing what is in iOS 5. iCloud being saved for last, so I expect great things. Plus, don’t forget our “One last thing…”

iOS 5 Top 10:

  1. Notifications. Yes! This was a mess and very intrusive. Now can swipe down from top to see current list of notifications.
  2. Newsstand, iBookstore for magazine and newspaper publishers. Nice idea. I wonder how many Indie developers this impacted?
  3. Twitter integration! OK, wow. Explains a few moves made by Twitter over the past few months, particularly with authentication and third-party app support. Again, how does this impact the Indies?
  4. Safari (updated). Reader support (as can be found in Safari 5 for Mac), very nice. Reading List, for saving for later. Tabbed browsing, on the iPad anyhow (Excellent!).
  5. Reminders (Hmmmm… Wooly Tasks killer I think). Lots of interesting features that I had also thought of adding, but Apple has 1000s of more engineering resources than I do, so they beat me to the punch. Ah, the nature of the business. We’ll see.
  6. Camera (updates). Lots of enhancements, mostly in making taking a picture faster and easier. Using the up volume button to take a picture will be really nice. Rule-of-thirds guides. Built-in editing of photos.
  7. Mail (updates). More composing and editing options, in particular, rich-text formatting (YES!). Introducing a new keyboard layout that is thumb-centric and available system-wide.
  8. PC Free…no more tethering!
  9. Game Center
  10. iMessage, new messaging service for all iOS devices. Yay! iChat for iOS

AirPlay mirroring.

iTunes syncing wirelessly.

Available Fall 2011.

11:20 am Update…

iCloud. The Digital Hub that Steve Jobs talked about in 2001 has now moved to “the clouds”. iCloud stores your content “in the cloud” and wirelessly pushes it to all your devices.

MobileMe “wasn’t our finest hour”, but “we learned a lot”. MobileMe is dead. iCloud will subsume all the services of MobileMe, but everything is rewritten from the ground up, and the best news of all…

…it’s FREE.

iCloud is invisibly integrated into apps that need synching of data, such as Mail, Contacts, Calendar, etc. Wireless back-up (a’la “PC Free” feature above). Also backup purchase of iBooks, music, apps, camera roll (on iPhone), etc.

iCloud also has a feature called “Documents in the Cloud” for syncing Pages, Numbers, and Keynote documents. For developers, there will be an iCloud Storage API. And, it will work with PCs as well.

iCloud allows photos taken on your iPhone to automatically be synched onto your iPad. No more needing to tether, sync, sync, sync, … Up to 1000 images stored on your iOS devices, and anything you want to permanently keep, you just need to move into an album. Photos remain for 30 days, so grab them or lose them. There is a Push Photo Stream builtin to camera rolls which is where the syncing takes place.

iCloud is WiFi only due to immense amount of data being pushed. When carriers can reliably offer 4G or greater, then I’m sure it will move to the celluar network.

Finally, there is now iTunes in the Cloud. Buy a song, sync with all devices, automatically.

10:50 am update…

Just in time for “One more thing…”

iTunes Match. For those songs that you ripped from your personal CDs. iTunes will scan your music for non-iTunes purchased music, and voila, your songs are automatically in the cloud. No uploading needed, if they already exist in the iTunes Store. For the rest, they are uploaded. This is the rumored “Music Locker”, and it costs $25 a year (but if you had MobileMe, you still $74 ahead).

 

 

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Posted in Apple, iOS, iPad, iPhone, Mac OS, Macintosh, WWDC | Comments Off

Why Wooly Beast Software exists

June 6th, 2011

Seth Godin hits the nail on the head with this blog piece, “The taskmaster premium”.

If you are not following Seth Godin’s blog, why not? He’s got a lot of good things to say that every entrepreneur and startup should be taking note of.

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