Solipsism Gradient

Rainer Brockerhoff’s blog

Browsing Posts tagged Klicko

Klicko 1.1 (201) is up, with the aforementioned full keyboard access/VoiceOver support…

An hours-long outage somewhere inside my ISP made me re-evaluate the idea about a reachability transition callback. It seems to be reliable enough when the local network is involved, but when the clogged pipe is several routers away, it can go down – and never go up again.

So what I’m doing now is, while the network is down, retry with a direct reachability test every half hour or so; of course if the callback says it’s back up, I tear that timer down again. Seems to work OK.

Several interim builds of Klicko went up in the meantime, implementing this and other small changes. The latest one is now in testing; build 1.1 (201) will implement full keyboard accessibility and VoiceOver support. At least in the preferences panel part; the background process is still mouse-oriented, and I don’t foresee disabled people needing any of the Klicko functions. Still, it’s good practice since nearly all of the Klicko panel code will be re-used in the upcoming rewrite of Quay, and there it will certainly be useful.

Re: Klicko 1.1

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And, the reachability check explained below is now also present in Klicko 1.1 (189).

Re: Klicko 1.1

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Rainer Brockerhoff wrote:

Maybe I should, after all, implement regular automatic version checking? I dislike such automatic processes myself, but I’ll look into doing it less obtrusively.

So, it’s done; Klicko 1.1 (187) has automatic version checking.

Details were trickier than I had anticipated, but I managed to do it while increasing download size by only 44K (23%). Most of that is accounted for by a new helper application. The background process checks for updates periodically. If an update is out, the process runs the helper app to display an alert; the user can then ask the app to run System Preferences to download and install the update. (If the Klicko panel is already open, the helper app isn’t called.)

Re: Klicko 1.1

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And the first bug is fixed: you had to click twice in Exposé in some cases. So I pushed out 1.1 (181). This also has, again, the French localization, thanks to Ronald Leroux for rewriting it on short notice.
I think I’ll continue doing small, immediate bug fixes just by incrementing the build number, instead of doing lots of dot-dot versions like 1.1.2c15. The downside is that these small updates won’t get press releases or special mention on the version tracking sites; for now, I’ll just post a “developer note” on those when possible.
Currently the user has to check for updates by opening System Preferences, going to the “Installation” tab, and clicking on “Check for Updates”. I do get the impression that relatively few users do so regularly, or when they run into a bug. Maybe I should, after all, implement regular automatic version checking? I dislike such automatic processes myself, but I’ll look into doing it less obtrusively.

Klicko 1.1

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Details on the product page. More about it later here… must run.

Cocoa musings pt.3

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It’s been a while since the last post, but I’ve finally gotten past the boring parts of the new Klicko System Preference pane & background process. The latter is actually a per-user Launch Agent. I’d used launchd before in the last Quay implementation, but didn’t fully understand what I was doing.

Well, I still can’t claim I fully understand all, but I’m definitely getting better at this. As soon as Klicko 1.2 is out and working (hm, maybe that should be the other way around?) I’ll back-port everything I learned to Quay.

One important part of messing around with launchd agents is that you have to set everything up just so – permissions of the executable and of its containing folders, as well as of the controlling plist if it’s a global agent; and you have to run launchctl to load (register) the controlling plist with launchd. Only then, and if the conditions inside the plist are satisfied, launchd will run your agent for you.

Uninstalling your agent, usually for putting an updated version in its place, must also be done carefully. You have to unload it if it’s loaded (even though it may not be running at the time) before swapping in the new executable and plist. Ideally, to avoid wasting time, there should be an easy way to test if your agent is properly loaded – the user might have unloaded it manually, or whatever. Unfortunately, the only “official” way to do so is to run launchctl again, passing in the “list” parameter, and parsing the output; not ideal.

However, there’s a primitive API in place in <launch.h>, and in fact launchctl uses this API itself to communicate with launchd. Still, there’s no documentation about it; only some sample code. Also, there’s this recent reply on the launchd-dev mailing list:

Right now the <launch.h> API is only rated for
daemons checking in with launchd (ala SampleD).
It is not really designed for job management.
Rather, we recommend that folks do their job
management by fork/exec of launchctl.

Quinn “The Eskimo!”

Still, I thought it would be interesting to use this API to check on the agent; after all, if something fails you’ll get an error back, and nothing will be messed up. So here’s the code for doing so:

#include <launch.h>

static id GetFromLaunchData(launch_data_t obj);

static void Launch_data_iterate(launch_data_t obj, const char *key, void* dict) {

   if (obj) {
      id value = GetFromLaunchData(obj);
      if(value) {
         [(NSMutableDictionary*)dict setObject:value forKey:[NSString stringWithUTF8String:key]];

static NSDictionary* GetFromLaunchDictionary(launch_data_t dict) {
   NSMutableDictionary* result = NULL;
   if (launch_data_get_type(dict)==LAUNCH_DATA_DICTIONARY) {
      result = [NSMutableDictionary dictionary];
      launch_data_dict_iterate(dict, Launch_data_iterate, result);
   return result;

static NSArray* GetFromLaunchArray(launch_data_t arr) {
   NSMutableArray* result = NULL;   
   if (launch_data_get_type(arr)==LAUNCH_DATA_ARRAY) {
      size_t count = launch_data_array_get_count(arr);
      result = [NSMutableArray arrayWithCapacity:count];
      for (size_t i=0;i<count;i++) {
         id obj = GetFromLaunchData(launch_data_array_get_index(arr, i));
         if (obj) {
            [result addObject:obj];
   return result;

static id GetFromLaunchData(launch_data_t obj) {
   switch (launch_data_get_type(obj)) {
      return [NSString stringWithUTF8String:launch_data_get_string(obj)];
      return [NSNumber numberWithLongLong:launch_data_get_integer(obj)];
      return [NSNumber numberWithDouble:launch_data_get_real(obj)];
      return [NSNumber numberWithBool:launch_data_get_bool(obj)?YES:NO];
      return GetFromLaunchArray(obj);
      return GetFromLaunchDictionary(obj);
      return [NSNumber numberWithInt:launch_data_get_fd(obj)];
      return [NSNumber numberWithInt:launch_data_get_machport(obj)];
   return nil;

static NSDictionary* GetFromJobLabel(NSString* job) {
   NSDictionary* result = nil;
   launch_data_t msg = launch_data_alloc(LAUNCH_DATA_DICTIONARY);
   if (msg&&launch_data_dict_insert(msg, launch_data_new_string([job fileSystemRepresentation]), LAUNCH_KEY_GETJOB)) {
      launch_data_t response = launch_msg(msg);
      if (response&&(launch_data_get_type(response)==LAUNCH_DATA_DICTIONARY)) {
         result = GetFromLaunchDictionary(response);
   return result;

To use it, just call the last function like this:

   NSDictionary* dictionary = GetFromJobLabel(@"com.yourcompany.agentlabel");

and examine the dictionary. If it’s nil, some error happened, or your agent isn’t loaded into launchd.

If you do get a dictionary back, it will be autoreleased, and the “Label” key’s object should be equal to the string you passed in. There are two more keys that might be interesting to check: “PID” will contain your agent’s pid if it’s running, and will be missing if it’s not; and “LastExitStatus” will show you what your agent’s main() returned on its last run.

Note that most of the code above is actually based on the launchd source, converted to use Foundation objects instead of CFTypes.


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It’s been a couple of weeks since my last post, but I haven’t been idle. Well, a few of the holidays excepted, of course. Here’s what’s on my radar for the new year, or at least for the first months.

I’ve finally had time to look at the SnowLeopard (Mac OS X 10.6) beta. Can’t say much about it, except that there are interesting and significant changes in the infrastructure – important for programmers. I really hope that, once out, a majority of users will adopt it.

A consequence of seeing the 10.6 APIs is that I decided to do a serious rework of Klicko and Quay, so they’ll be ultimately easier to migrate to 10.6 and a 64-bit environment. Klicko inherited a lot of code, and I’m really glad that I decided to do it as a training exercise, since I’ll very soon back-port much of that back to Quay, after enhancing and optimizing.

If all goes well, Klicko 1.1 will be out soon. I’ve got all but installation and updating procedures done. Most notably, it’s now a System Preferences panel that installs a background process. While this is a departure from the easy-to-run, simple-Cocoa-app mantra, splitting this type of application into a faceless background process and a foreground GUI will soon be mandatory for all practical purposes, and there are advantages; for the user, once properly installed and configured, Klicko will “just work” automatically and in the background, and use very few resources.

One new Klicko feature was requested by several users (and others who have emailed me in the past). There will be a (configurable) preference to have the window’s “zoom” button do a true maximize – or at least attempt to, not all applications will support it properly. While I find the importance that Windows users attach to maximizing everything all the time a little puzzling, trying it out convinced me that it’s useful now and then. I always maximize NetNewsWire, Xcode, and a few other application windows, for instance. I also decided that it may be useful in pointing users that are new to the Mac to shareware software in general and to my own applications.

Once that is done – hopefully with very few build updates – it’s back to reimplementing everything I learned into Quay (probably 1.2). I’m not decided whether that will become a preferences panel too, but it may be possible. More importantly, I’m now pretty fluent with the event tap and accessibility APIs that both Quay and Klicko use.

The major new feature of Quay will be that Quay menus will also pop up for Finder icons. Ultimately, I’d like to make this work in any and all Finder window modes – icon, list and column – and in all circumstances where the Finder’s own contextual menus pop up. I’ve done some preliminary testing and it looks like it might be possible. There are a few edge cases where I’m not sure that I’ll be able to compute the correct path for the icon.

Anyway, if all works as planned, I’ll be able to introduce more flexibility through plug-ins. A plug-in would get a file or folder handed to it and would produce either a popup menu, or an information window. This would allow me to finally declare XRay entirely defunct (it already runs very poorly on Leopard), and replace it with many small, specialized plug-ins. My older contextual menu plug-ins, like Zingg! and Nudge would also be trivial to rewrite as Quay plug-ins.

A similar, much more ambitious plug-in scheme, was planned for XRay II, and I can reuse some of that code… there are still some complex issues to decide, however. Opening the plug-in interface to other developers is of course what I’d like to do, but licensing, updating, keeping plug-ins from interfering with each other will be very tricky.

All in all there’s lots of ideas to implement and this should keep me busy for most of the year. I’m not considering going into iPhone/iPod development for now; there’s a glut of $0.99 applications and the way the App Store is working seems overly opaque to me.

More soon! Stay tuned.

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