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ContributeCode sign and notarize your MacOS Screensaver to avoid Gatekeeper restrictions
The last time I built a screensaver was for the 2008 US Presidential election and back then all you had to do to distribute your binary was stick it on a web site and wait for people to download it. Doing this nowadays results, at best in platform warnings about running arbitary software downloaded from the Internet and at worst inability to run the software at all. Actually, I think this is probably pretty sensible but it meant I needed to jump through some hoops to get my MacOS Patrick O'Brian Mapping Project screensaver to run on other people's computers.
Some Googling led me to the 2019 WWDC announcement on the updates to how MacOS handles software distributed outside the app store. Unfortunately because of the way the MacOS screensaver process works, you can't distribute a native screensaver through the app store, so notarizing my app was the only way to go.
This post on the Apple developer forums actually describes the steps you need to follow, but I thought that a more explicit example might be helpful.
1. First thing you will need is a "Developer ID Application" certificate. That post I mentioned talks about using a "Developer ID Installer" certificate but that seems to be what you use if you are packaging your screensaver in an installer (which the OP isn't). Not sure if either way works, but I went with the "Developer ID Application" certificate to notarize my zip.
2. Once you have generated your cert (if you didn't already have it), downloaded and installed it in the KeyChain Access (by double clicking on it), you will need to codesign the screensaver binary ([your-screensaver].saver file). So something like this (the name is what will be listed in the names column in KeyChain Access once it is installed):
/usr/bin/codesign -f -o runtime --timestamp --sign "[Developer ID Application Name]" [your-screensaver].saver.
If your screen saver depends on external libraries, like SQLite for instance, you'll need to sign that as well. This post on the Apple forums explains that dependancies are signed inside out ("That is, if A depends on B, sign B before you sign A. When you sign A, the code signature encodes information about B, and changing B after the fact can break the seal on that code signature."). So for me, I needed to run codesign twice like this:
/usr/bin/codesign -f -o runtime --timestamp --sign "[Developer ID Application Name]" [your-screensaver].saver/Contents/Frameworks/SQLite.framework/Versions/A/SQLite /usr/bin/codesign -f -o runtime --timestamp --sign "[Developer ID Application Name]" [your-screensaver].saver
3. Now you have signed the .saver file, you can zip it up. So you'll now have a [your-screensaver].saver.zip file.
4. Now you need to notarize the zip file. For this you'll need an app specific password which you can generate on your Apple ID account page. Once you have that you can run the xcrun altool (N.B. xcrun lets you store and access passwords stored in the keychain if you need to put this in a script which you probably should do. Check out the help for --store-password-in-keychain-item for details on that).
/usr/bin/xcrun altool --verbose --notarize-app --primary-bundle-id "[Your application bundle ID]" -u "[Your Apple ID username]" -p "[The app specific password you generated]" -t osx -f [your-screensaver].saver.zip
5. If you are like me and your Apple ID is associated with multiple "provider accounts" (I am on several teams), you need to tell xcrun altool which provider you want to notarize with. So first you get the list of providers and then add the appropriate one to your notarize command:
/usr/bin/xcrun altool --list-providers -u "[Your Apple ID username]" -p "[The app specific password you generated]" /usr/bin/xcrun altool --verbose --notarize-app --asc-provider [The ProviderShortname from the list of providers] --primary-bundle-id "[Your application bundle ID]" -u "[Your Apple ID username]" -p "[The app specific password you generated]" -t osx -f [your-screensaver].saver.zip
6. Ok. We are almost there (I promise). The notarization process takes a while as this tool talks to Apple servers about arcane stuff in your binary. You can check on it's progress with the following couple of commands (the first gets the history of notarization attempts and the second gives you the results for a particular RequestUUID):
xcrun altool --notarization-history 0 -u "[Your Apple ID username]" -p "[The app specific password you generated]" --asc-provider [The ProviderShortname from the list of providers] xcrun altool --notarization-info [The RequestUUID in the Notarization History list] -u "[Your Apple ID username]" -p "[The app specific password you generated]" --asc-provider [The ProviderShortname from the list of providers]
7. Hopefully if that all works you'll get an email telling you the notarization was successfull (or not). If there was an error you'll need to open the link (LogFileURL) in the notarization-info output to figure out why. For me my first attempt failed because I didn't realise I needed to codesign the SQLite dependancy.
8. Now you need to "staple" the notarization ticket to the screen saver application. Weirdly, even though you notarized the zip file, you can only staple to the application binary. To do this, you can just run this command:
xcrun stapler staple [your-screensaver].saver
This will generate some output like this (if all goes well):
Processing: /Users/.../[your-screensaver].saver The staple and validate action worked!
Now you can delete the old zip (yep, the one you originally notarized) and re-zip the freshly stapled [your-screensaver].saver then distribute your [your-screensaver].saver.zip to your heart's content.
Permalink - Comments - Tags: Development
Patrick O'Brian Mapping Project Screensaver
I have completed a 1.0 version of my Patrick O'Brian screensaver. This software should work (no guarantees) on MacOS 10.12 (Sierra) or later. To install, unzip and then double click Voyages.saver. You will be asked to install the screensaver for "this user" or "all users". Please see the terms of use below (N.B. Satellite imagery is provided by and copyright © MapTiler © OpenStreetMap contributors).
If you aren't interested in the implementation details and would like a copy, you can skip the rest of the post and download the screensaver here:
DownloadN.B. I am pretty sure I jumped through all the hoops I need to so that this screensaver can be installed without dire warnings, but please let me know if you aren't able to install it.
I wanted a full screen satellite map with the characters journeys (based on my latitude/longitude data) rendered on top. There are native libraries out there to do that kind of thing, but I thought it would be interesting to try and do some of this myself.
I started out hunting around for the Web Mercator Projection algorithm that GoogleMaps uses. There is a pretty good explanation of this in the Google Maps Javascript API docs. I do wonder though how that Javascript code translates to the projection formulas for x and y. I am missing something there.
Someone had kindly ported that code to Swift so I was able to use that to get latitudes and longitudes successfully projected onto the screen:
Next step was to get hold of a satellite imagery tileset (obviously based on the Mercator Projection) that was free and easy to embed in my native app (no dependancy on an Internet connection for me). Fortunately OpenMapTiles had exactly what I needed. I didn't really need the full 186Gb dataset (although if I had a spare pile of cash lying around it would be fun to play with) so I grabbed the low res tileset.
The download is basically just a SQLLite database file that you embed straight in your app. You can query a particular tile row,column and zoom level (the low res dataset has zoom levels 0-5) and extract the jpg data (the data format info is actually in the db so you can query that) into a byte buffer that you can pass stright into NSImage. Apart from some teething problems with the screensaver binary, this worked pretty well and I was able to get tiles rendering onscreen pretty quickly:
It's not particularly performant and I'm sure I could improve the animation by using GL or Metal directly, but I think it is good enough to warrant moving on to something new.
Copyright (c) 2020 Tom Horn. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Redistributions in any form must be accompanied by information on how to obtain complete source code for the DB software and any accompanying software that uses the DB software. The source code must either be included in the distribution or be available for no more than the cost of distribution plus a nominal fee, and must be freely redistributable under reasonable conditions. For an executable file, complete source code means the source code for all modules it contains. It does not include source code for modules or files that typically accompany the major components of the operating system on which the executable file runs. THIS SOFTWARE IS PROVIDED BY TOM HORN ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL TOM HORN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Permalink - Comments - Tags: Development,Patrick O'Brian
A Patrick O'Brian Atlas
After I finished my atlas of all the Patrick O'Brian novels I thought it might be cool to see all the courses I plotted on a single world map. I am working on an Apple MacOS screensaver to animate the maps, but in the meantime, here is a rendering of all the voyages.
You can click on the image for a higher resolution view.
If you are wondering about the occasional breaks in the course lines? They are a result of sections of the story where I couldn't guess where Jack and Stephen ended up. In those cases I pick up their location again once I had a fair weather observation.
Permalink - Comments - Tags: Patrick O'Brian
Bundle.main.path forResource will return nil in a MacOS screen saver
I thought it might be worth writing a quick post on something that had me stuck building a screen saver for MacOS in Swift.
If you have a file you include in your build target (like a SQLite database of map tiles) and need to open that file you might try something like this:
let stringPath: String? = Bundle.main.path(forResource: "satellite-lowres-v1.2-z0-z5", ofType: "mbtiles")
Because I am debugging my application in a regular MacOS app (that just shows my ScreenSaverView) this code worked fine when I was debugging. As soon as I built and deployed the actual screen saver bundle everything broke.
So at that point you might spend quite a bit of time trying to debug entirely unrelated tile loading code before realising that bundle.main.path forResource was returning nil, but only in the screen saver application.
The reasons for this is that MacOS screen savers are bundles loaded by the system screen saver application, so the path you get will be something like:
/Applications/System Preferences.app/Contents/Resources
So to get this to work (in both the test app and the screen saver app) you need to get the bundle via a class in that bundle:
let stringPath: String? = Bundle(for: type(of: self)).path(forResource: "satellite-lowres-v1.2-z0-z5", ofType: "mbtiles")
I am just using the ScreenSaverView class which works fine.
This all took a little longer than it should have to find because, this being my first MacOS app, I wasn't sure where debug logging was ending up. Turns out it all appears in the Mac Console application ("Console" in Spotlight). I also struggled a bit because the Console app, or something in the MacOS logging framework was making decisions about the sensitivity of variables I was logging. So logging something like this:
os_log("Location was ---> %s", stringPath ?? "We got nil for our stringPath")
Ends up in the logs like this "Location was --->
os_log("Location was ---> %{public}s", stringPath ?? "We got nil for our stringPath")
Permalink - Comments - Tags: Development, Swift
All This Started Four Years Ago - By a Special Correspondent
This article by "A Special Correspondent" was in my grandfather's papers, along with other letters written at the time on what I believe is the same typewriter (something I'd love to be able to confirm). I haven't been able to find this text elsewhere so I am publishing it here.
Chilling given the recent resurgence of Nationalist rhetoric.
Late in the afternoon on Friday, 11th March, 1938, I was listening in to my radio in Vienna, waiting for a speech by one of the political leaders in Austria on the occasion of the plebiscite which Dr. Schuschnigg, chancellor of Austria, had ordered to be held on the following Sunday. The Austrian people were called upon to decide whether they wanted to remain independent, or become part of Nazi Germany.
While I was wondering why the speech did not start at the appointed time, the radio speaker suddenly said: "The chancellor, Dr. Schuschnigg, is going to make an important announcement. Then I heard Schuschnigg's voice through the loudspeaker, saying "The German Government have requested my Government to cancel the plebiscite which we had decided to hold the day after to-morrow, and to hand over the Government of Austria to nominees of the German Government. Failing this, the German Government would order German troops ready for that purpose to cross the Austrian border at 8 p.m. to-night. According to reports received, German troops are already on Austrian soil. As our troops are far inferior in numbers and equipment to the invading forces, I have, in order to avoid needless bloodshed, ordered our troops not to resist, and tendered my and my Government's resignation to the President. God save Austria!"
I shall never forget Haydn's variations on the Austrian National Anthem that were played after this. Then the announcer introduced the new chancellor of Austria, Seiss-Inquardt, an Austrian, the first of the long line of men whom we have become used to call Quislings for their betrayal of their own country to the Nazis. Yet, Quisling won his doubtful fame long after Seiss-Inquardt had committed the same infamy.
The world knows now that Hitler resorted to his first act of using military force against another country because he had to prevent at all costs the plebiscite in Austria, which would have plainly shown what a big majority of the Austrian population was opposed to the Anschluss. It also has been revealed in the meantime that he had by no means been certain of the success of his threats, and that a firm stand by the western powers by Austria's side would have prevented the occupation of the country. When at that time I made up my mind immediately to leave Austria and go to Australia, it was because of the certain knowledge that the events of those days were the start of an avalanche from which you could expect to be safe only in the place farthest away. Yet, with all my pessimism at that time I - and probably nobody - would not have imagined that only four years later even the great Australia, 13000 miles distant would be threatened similarly.
It is strange and interesting to think how many things - apart from the names - were similar in Australia and Austria. Like Australia, Austria was a federation of states, and there was a federal government and parliament as well as state governments and parliaments. The same problems of overpopulated cities with many unemployed, and lack of farm labour in the country existed. Austria, like Australia, had gone through a terrific depression after the last war. The Austrian population was reputed in Europe for friendliness and a free and easy way of life. When they saw the pest of Nazism developing in the neighbouring country of Germany, on a stone's throw over the border (oh God, why the stone to destroy the monster never thrown?), they also used to say: "It can't happen here!"
The way it did happen might possibly teach us a lesson. In Austria there existed great political differences between the various groups of the population, just like elsewhere. This, accompanied by lack of restraint on the part of the elected representatives of the people in the various legislative bodies, weakness of the government because of a very small majority in the parliament and different political tendencies of various state governments, paralysed public life to a great extend and led to widespread distrust in politicians. The Nazis made clever use of these conditions. Their propaganda against "politicians" made the ordinary man believe that he could do better without any of them, forgetting the fact that a country with democratic institutions, even if the politicians are not the best, is infinitely better of than one without any, but Nazi chiefs instead. The Nazi methods of propaganda were most interesting to watch. They posed as Austrian super-patriots, with Austria first and everything else only a long way afterwards The Nazi methods of propaganda were most interesting to watch. They posed as Austrian super-patriots, with Austria first and everything else only a long way afterwards. The of course thundered against all sorts of "isms", parliamentarism, capitalism, socialism, communism, against democracy and British and Jewish world domination. Those poor Jewish refugees from Germany in 1933 to 1937 who had believed to find a haven of security in Austria were their special targets. And for the small man it was so immensely relieving to be told that all his every-day troubles were only due to one or several of those isms, and particularly to the Jews and the refugees; with himself, he heard, there was never anything wrong whatsoever; he was of Aryan descent, and that alone made him ever so far superior to anyone else. It was cleverly done, and many simpletons fell for it.
To-day, only four years after all this happened on the other side of the world, we in Australia are confronted by similar dangers. It might not be inappropriate to look back and try to guard against mistakes that led to the start of all this four years ago.
Permalink - Comments - Tags: World War Two,Misc
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