// do something here

I was looking around for a view that somebody had previously put together to show a modal view to allow the selection of a date and time, and found nothing.  This seemed like something reasonable to expect to find.  Apparently, none of the umpteen thousand fart application developers have ever had a need to create a date and time picker view, or if they did, they did not feel the need to share their creation with the world at large.

So here it is.  This is what it looks like when you use it in your application:

Here is the code that you would use to instantiate the view in your parent view controller, where selectedDate is the default date that you want the view to display when it opens up:

DateTimePicker *controller = [[DateTimePicker alloc] init];
controller.delegate = self;
controller.defaultDate = selectedDate;
[self presentModalViewController:controller animated:YES];
[controller release];

To receive messages back from this modal view, you just need your parent view to follow the DateTimePickerDelegate delegate, which means you would need to have the dateTimePickerOK and dateTimePickerOK methods in your parent view.  These methods are called when the user taps the Save or Cancel buttons respectively on the modal view.  Here is what those methods could look like:

- (void)dateTimePickerOK:(DateTimePicker *)controller didPickDate:(NSDate *)date
{
    self.selectedDate = date;
    [self redrawDate];
 
    [controller dismissModalViewControllerAnimated:YES];
}
 
- (void)dateTimePickerCancel:(DateTimePicker *)controller
{
    [controller dismissModalViewControllerAnimated:YES];
}

I have put together a sample application that demonstrates the use of the date and time picker view, which also of course includes the DateTimePicker header, implementation, and NIB files.  Please feel free to use these in our own code, and if you make any cool changes to it, please let me know so that I might include them in my example or ridicule you in the posting comments.

The sample code zip file is here:

DatePickerExample

Have you ever had a situation where all of those nested try/catch blocks just get in your way when trying to chase down a problem? I just hate that.

Luckily, in Visual Studio 2008 (and other versions, I am sure), there is a handy dandy way to disable all of the try/catch blocks when you run the application in debug mode from the IDE.  Just go to the Debug menu, select Exceptions, click the box under the Thrown column for Common Language Runtime Exceptions (or others if that is what you are looking for), and click OK.  Now when the code has a problem, you see it right away instead of trying to work backwards through nested try/catch blocks in different classes and modules.

Just don’t forget to put it back to the way it was when you are done. I am not a huge fan of try/catch blocks, but their normal use definitely has its place.

This VB code was brought to my attention.  It is meant to look at a string variable (prefixText) and decide if the string is numeric or not, and return a data set (ds) by using a different method based on the result of the numeric test. (As always, this code is in a heavily used production environment.)

If Left(prefixText, 1) = "0" Or Left(prefixText, 1) = "1" Or Left(prefixText, 1) = "2" Or Left(prefixText, 1) = "3" Or Left(prefixText, 1) = "4" Or Left(prefixText, 1) = "5" Or Left(prefixText, 1) = "6" Or Left(prefixText, 1) = "8" Or Left(prefixText, 1) = "9" Then
    ds = New Users(_ConnStr).getUsersListByNumber(prefixText)
Else
    ds = New Users(_ConnStr).getUsersListByLastName(prefixText)
End If

I have some great ideas on how to improve this code. The first thing I would have done was to use OrElse instead of Or, it would speed things up tremendously. And I would also have added in the test for the “7” character.

Sorry about the delay between posts, readers. I have been fighting with getting as much coded as possible with our newest iPhone application, along with fighting with bugs and crashes in our existing iPhone applications. The App Store approval process continues to baffle me to no end.

From a development perspective, one thing I learned the hard way was to make sure that the dealloc methods in the classes that you roll in Objective C need to have the [super dealloc]; come last. If it does not come last, your code may or may not have memory problems and crashes.  If you are not sure if you are always doing this last, check your classes now.

Go ahead and check, I’ll be here when you get back.

Thanks to a little assist from my coworker John Boker, the amazing Asteroids javascript from Erkie is now fully integrated into this here very web site. Alls you have to do is type asteroids on any web page of this roided up web site (just make sure the focus is not set on a text field or the URL field), and blast away.

Here is the javascript that I added to the footer of my pages:

<!-- asteroids -->
 
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
 
    <script type="text/javascript">
        function asteroids()
        {
            var s = document.createElement('script');
            s.type = 'text/javascript';
            document.body.appendChild(s);
            s.src = 'http://erkie.github.com/asteroids.min.js';
        }
        var roids = "";
        $(document).keypress(function(e)
        {
            roids += String.fromCharCode(e.which);
            if ("asteroids".indexOf(roids) != 0)
            {
                roids = "";
            }
            else if (roids == "asteroids")
            {
                roids = "";
                asteroids();
            }
        });        
    </script>

Enjoy.

I don’t like to get strange memory crashes in my applications. So imagine my surprise today when I changed over some CFUUIDRef ivars to NSString, and as a result, I started getting some weird EXC_BAD_ACCESS messages.

For your perusal, consider listing A, where my class is being initialized with a nonatomic and retained property:

@synthesize nameString;
 
- (id)initWithData:(NSString *)inNameString
{
    self = [super init];
 
    if (self)
    {
        nameString = inNameString;
    }
 
    return self;
}

After awhile of beating my head against the wall, I changed it to look more like listing B:

@synthesize nameString;
 
- (id)initWithData:(NSString *)inNameString
{
    self = [super init];
 
    if (self)
    {
        self.nameString = inNameString;
    }
 
    return self;
}

I leave it to the reader to investigate this phenomenon. It is not too complicated, but if the subtlety is lost on you, there is always a memory based crash lurking around the corner.

Needless to say, if you are having strange memory crashes in your application, and your class looks like listing A, change it to look more like listing B. And if your app looks like listing B, it is working fine and you want to see how bad bad can really get, change it to look more like listing A.

After using my latest iPhone application on a device for a while, I was getting the following crash:

Program received signal:  “EXC_BAD_ACCESS”.
(gdb) backtrace
#0  0x33369ebc in objc_msgSend ()
#1  0x320e5248 in -[UIScrollView(UIScrollViewInternal) _scrollViewAnimationEnded] ()
#2  0x338b4a14 in -[NSObject performSelector:withObject:] ()
#3  0x320e5098 in -[UIAnimator stopAnimation:] ()
#4  0x320e4b7c in -[UIAnimator(Static) _advance:] ()
#5  0x320e4a34 in LCDHeartbeatCallback ()
#6  0x34350e60 in HeartbeatVBLCallback ()
#7  0x332e91c0 in IOMobileFramebufferNotifyFunc ()
#8  0x316532f8 in ?? ()
#9  0x33866b50 in __CFMachPortPerform ()
#10 0x338ae52a in CFRunLoopRunSpecific ()
#11 0x338adc1e in CFRunLoopRunInMode ()
#12 0x3434e1c8 in GSEventRunModal ()
#13 0x32002c30 in -[UIApplication _run] ()
#14 0x32001230 in UIApplicationMain ()
#15 0x00002ff8 in main (argc=1, argv=0x2ffff550) at /Developer/svn/MyCompany/iPhone/MyApplication/Other Sources/main.m:14

As you can see from the trace, the only mention of my code in there is the call to main.

I ran Build and Analyze from Xcode, and also set it up to run the clang analyzer on my project from the Terminal, and both of these did not find any problems in the code.

After using the NSZombieEnabled flag in the application, it came up with this message in the console:

2010-09-11 17:10:33.970 MyApplication[9321:207] ***
-[MyViewController respondsToSelector:]: message sent to deallocated instance 0x7489480

I think we finally tracked down a way to keep the error from occurring. I am guessing that the view was being deallocated and released while it was still undergoing a scroll animation. I changed my code to be like this:

[myTableView selectRowAtIndexPath:[NSIndexPath indexPathForRow:idx inSection:mainSection]
        animated:NO scrollPosition:UITableViewScrollPositionMiddle];

The application has not crashed with the same error since I changed all of these selectRowAtIndexPath calls to use the NO flag for the animated property. True, this does not fix the problem, but at this point, hiding it was good enough for me and our complaining customers.

Tonight I attended the Central Ohio .NET Developers Group meeting at the Microsoft office in Polaris. Jeff Blankenburg gave a presentation on developing applications for the Windows Phone 7 platform, and Mel Grubb gave a short talk on the Should open-source testing library.

Jeff’s presentation was very high level, but still informative. He did confirm my biggest disappointment on the platform, and that is the glaring lack of a data store. I guess that Microsoft couldn’t find anyone to port over the SQL Mobile 2005 code. Or maybe even the SQL Server Compact code. Or the SQL Server Mobile Edition code.

After 9 days, my company’s second iPhone app, Football Statware, was approved on Sunday, August 22, 2010, and is available for download from the App Store.

I have already pushed an update to the application with a few minor fixes, we will see how long this update takes.

While the set up pictured below was not our equipment, I am still kind of glad that our servers are not hosted at this facility any longer.