If you need or want the date and/or time the last time your app was built then there are two handy macros you can use. Consider the following example:

char *date = __DATE__;  // e.g. 'Dec 15 2009'
char *time = __TIME__;  // e.g. '15:25:56'
 
NSLog(@"Build date: %s", date);
NSLog(@"Build time: %s", time);

I tested it with GCC 4.0, GCC 4.2 and even the new LLVM GCC 4.2. It worked fine with all three compilers.

Those are precompiler macros which work by getting the precompiler to replace them with the current date and time when the file in which they are located in gets built. Bear in mind that generally building is incremental and therefore these will only get updated if there really IS a new build happening. That’s a drawback if you forget it, but you can or should always do a build – clean before you build a release or distribution version to make certain all got updated.

Since those macros date back to C times they get replaced with C-style strings. That’s a pointer to a char array with a binary zero at the end to terminate the string. To convert them to obj-C NSStrings is simple by means of the %s formatter or by using one of the more complicated initializers of NSString.

char *date = __DATE__;
char *time = __TIME__;
 
NSString *myDate = [NSString stringWithCString:date encoding:NSASCIIStringEncoding];
NSString *myTime = [NSString stringWithFormat:@"%s", time];

Finally if you are really so much “pro” that the build time of your app matters, then you will probably also ask if there is a way to force building of certain files to forego the incremental building. Sure you can. All you need to do is to add an extra script to your target to set the last modified time of the file using these macros to the future.

touch -t 2012310000 "${PROJECT_DIR}/Classes/CalendarAppDelegate.m"

It’s not enough to simply set the modified time once because then the next modification sets it back to the current date. Thus the need for this simple unobtrusive script, in this example I am setting the modified time for CalendarAppDelegate.m to Dec 31st 2020 which is sufficiently far away so that this blog article will work for the next 11 years. 🙂

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When I started on Twitter, I tried out a few Twitter clients both on Mac and iPhone until I quickly settled on Tweetie. When Loren Brichter made the bold move to sell Tweetie 2 as a seperate app I also purchased it because I am convinced this guy means quality and Tweetie 2 is on the first page of my springboard.

One thing that’s cool about Tweetie 2 is the fresh paradigm to refreshing the contents of a table view. Up until now we had been looking for space to mount a reload button on, sometimes having to resort to adding an extra tool bar for just one view so that you can have enough space. Now if you have a tableview that it sorted reverse chronologically, then you have a natural urge to make new items appear at the top by pulling down the table with extra force.

Loren recognized this need and innovated the Pull-To-Reload paradigm. If you want to refresh a tableview in Tweetie 2 then you simply pull down the table far enough for an additional cell to appear at the top with the instruction “Pull down to refresh”. If you do, then at a certain point the arrow rotates and the text changes to “Release to refresh”. All accompanied by two distinct wooshing sounds and a pop once the reloading action has ceased. The Intuitiveness of this paradigm is so compelling in fact that people who use Tweetie 2 start to try to refresh ALL tableviews like this.

Might be a good case to make this the standard way from now on because it feels more logical and natural than to tap on a small button with a circular arrow on it. A user of MyAppSales requested that I add this mechanism for reloading reviews of individual apps. At first I thought this to be advanced magic, probably using forbidden techniques. But after a bit of research and lots of hints coming from my Twitter friends (thanks Thomas and Fabian) I figured it out. This article explains how I did it.

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