Catalina GIFfing: Quick workflow from screen to animated GIFs

All the leaves are green.

And the sky is blue.

I’ve been at my desk.

With screenshot play…

(To be fully truthful, it’s currently raining cats, dogs, kittens, and puppies. But it’s lovely here in the high desert.)

With my newly updated workflow creating the following GIF took about a minute maybe from start to post. The secret? QuickTime Screen Recording (bless you ⌘-Shift-5) and “gifify” courtesy of Homebrew. Set record, demo, stop, convert, drop into WordPress:

I love how easy it is to invoke screen recording these days with macOS’s updated capture interface. It’s especially nice how the optional delay time allows me to get into the zone before recording actually starts.

Back to installation, the blocker was getting homebrew to get itself into position to fully support Catalina. I had to apply homebrew update and homebrew upgrade and homebrew doctor a number of times. Not only did I get gifify installed, but ffmpeg is finally back to working and I once again have emacs for all my git needs.

I’ll spare you how bad the emacs transition was other than to say if you have to disable system integrity and mount read-write by hand, you’re probably doing it the wrong way.

With ffmpeg, it was the dependent libraries including the ones already installed into macOS (like openssl ). Homebrew refused to link:

Warning: Refusing to link macOS provided/shadowed software: openssl@1.1

I wish I had known early about the update/upgrade/doctor approach applied multiple times by the way, not just once, until everything stops complaining and the doctor says “Your system is ready to brew”. Because at that point, installs are a breeze. Installing before then, when the configuration seemed irreparably broken was probably a bad choice.

I spent a bit of time after removing my current bandaid symbolic links. It seems to have helped that I ended up granting separate privileges to ruby in Security & Privacy a while ago. I don’t remember why I did but it’s in there and I vaguely remember going through the process while cursing Cat.

June’s almost here and I wonder if Catalina.successor() will be better or more of the same. It hasn’t been a good Cat year for me.

Musings on `Result` and building a command line utility with completion handlers

Collaborating with Paul Hudson is a pleasure but the time difference can be, well, confusing. So when I started putting together an outline about the new command line argument parser for Pragmatic, one of the first things I wrote was a command line utility to tell me what time it was in Bath, UK:

% now bath uk
Bath 4:16:42 PM (GMT+1 United Kingdom Time)

I use CLGeocoder to use whatever terms I enter after the command as the hints to look up places of interests. I grab the first match and pull the time zone from that match (or throw an error if there’s no possible match).

Command-line utilities are not particularly well known for their asynchronous feature support. Because geocodeAddressString does run asynchronously, I use the quick and dirty trick of starting a runloop that executes until the completion handler finishes. I’m basically adapting an async method to sync.

This gave me an opportunity to finally get around to using the new Result type. Restrictions on other projects prevented me from kicking its wheels (or I was already using my own version from way back).

I struggled a little with how to incorporate Result. Here’s an earlier go at this. I use an optional resultto store the result, which is then set in completion scope:

var result: Result<[CLPlacemark], Error>?

CLGeocoder().geocodeAddressString(hint) { placemarks, error in
    switch (placemarks, error) {
    case (_, let error?):
        result = .failure(error)
    case (let placemarks?, _):
        result = .success(placemarks)
    default:
        fatalError("Geocoder error, no results.")
    }
    CFRunLoopStop(CFRunLoopGetCurrent())
}
CFRunLoopRun()

This code bothered me, and not just because I had to test and unwrap result when control returned to the main part of my method. It seems so obvious that Result should have a simple initializer based on the common elements found in legacy completion handlers. This would collapse those arguments to, for example, completion(Result(error, data)). Unless I’m missing something big here, I thought to build my own convenience initializer:

extension Result {
    init(_ success: Success?, _ failure: Failure?) {
        precondition(!(success == nil && failure == nil))
        switch (success, failure) {
        case (let success?, _):
            self = .success(success)
        case (_, .let failure?):
            self = .failure(failure)
        default:
            fatalError("Cannot initialize `Result` without success or failure")
        }
    }
}

That extension allowed me to collapse the code down to this. Notice how I can use the initializer here to eliminate the optional result, simplifying my extraction with get, towards the end. Admittedly, it’s not always easy to come up with an initial value that can be overwritten this way, but here it worked. The handler became two lines long, and processing the result to get my placemark (including all error handling), another two lines:

static func fetchPlaceMark(from hint: String) throws -> CLPlacemark {
    var result: Result<[CLPlacemark], Error> = Result([], nil)

    CLGeocoder().geocodeAddressString(hint) { placemarks, error in
        result = Result(placemarks, error)
        CFRunLoopStop(CFRunLoopGetCurrent())
    }
    CFRunLoopRun()

    let placemarks = try result.get()
    return placemarks[0]
}

I quite like my initializer and wonder why something like that doesn’t already exist unlike init(catching:() -> Success). I’m curious as surely I’ve missed something important. Even in normal completion handlers, I’d imagine using the legacy Error? and Data? optionals would be a common use-case for Result

Let me know.

Broken App Store downloads on Mojave: We could not complete your purchase

This has been happening to a lot of people recently. You open App Store and try to update apps or download new ones. Instead:

And if you have 48 apps to update, you have to click OK 48 times. Argh.

I spent nearly two hours with Apple yesterday trying to resolve.

Instead, I should have just tweeted because when I did Bas Broek had the answer almost immediately:

I had already rebooted, reset NVRAM/PRAM, cleaned out my Application Support for the App Store, and, get this, at the advice of Apple itself, reinstalled freaking Mojave to try to resolve it.

What a waste of time.

I hope this may come up in someone’s Google search to save them time.

  1. Quit App Store
  2. At the terminal: open $TMPDIR/../C/com.apple.appstore/
  3. In Finder: trash everything in that folder including any pending updates / stuck items.
  4. Relaunch App Store
  5. Done

Update: Gwynne Raskind adds: “$TMPDIR/../C is confstr(_CS_DARWIN_USER_CACHE_DIR)”.

Catalina permissions: Chrome, Zoom, etc

Ran into trouble this weekend where I was unable to add permissions for a number of apps to allow access to my microphone and camera.  (And yes, I’m aware of the security horrors of Zoom but I had work to do.)

They wouldn’t give the normal permissions request:

Instead, I got a message directing me to System Preferences:

Once there, the prefs did not list the app for normal check-to-enable:

I couldn’t unlock and drag on an app.

With some help from Bas Broek and this article, which specifically addressed the inability to grant access in Catalina, I discovered that rebooting with a NVRAM/PRAM reset might help. It sounded like sacrificing chicken entrails but it worked. While a regular reboot didn’t help, the Cmd+Option+PR reboot did.

Apple Support Article: How to reset NVRAM or PRAM on your Mac.

I hope this helps someone else to avoid the time I wasted.

So you’re going to teach remotely…

Remote meetings and teaching are an unfortunate necessity of the times. For those of us already using these platforms in positive ways, perhaps we can share some lessons on how to enhance your toolset.I thought I’d put together a quick post to address some of the ways things the classroom experience changes and suggest some technology support  for online classes.

I apologize for the stream of thought and incompleteness of this post. I wanted to put something out there right away. I’ll try to add, edit, and revise when time allows.

All Cameras On

I found the biggest struggle was my inability to wander through the classroom, peek over shoulders, and talk quietly to individual participants. I’m a walker and the online classroom is very much one of staying still.

My first rule is all cameras on with a further all cameras on faces. People are often uncomfortable with this, either switching their cameras off or pointing them up to the ceiling, essentially isolating themselves as students in a way they cannot do in a normal classroom, even by sitting at the very back with a phone in their lap. Push back and be insistent.

This rule goes a long way towards bringing the classroom together and making up for the fact that so much of the teaching experience is limited to a single viewpoint. The teleconferencing Zoom site offers a camera grid feature, which displays all participants at once (although not necessarily on the same screen, you will have to page through for large gatherings). This feature is especially important when you give in-class exercises, allowing you to keep track of the emotional temperature and find students who may be struggling.

Unfortunately, Zoom does provide an equivalent “screen peek”, so you cannot look over shoulders. Each screen must be shared and viewed individually.

As you teach, make sure you encourage participation, even more than you would in a normal classroom as there is always a danger of getting lost in your monotone without the immediate ability to “read the room” as you teach. Be extra conversational with give and take, much more than you would in a traditional class or seminar. This helps offset the technology and creates a warmth and inclusivity that otherwise would be missing.

Take Breaks

If you’re teaching extended classes, workshops, or labs, make sure to offer regular breaks to stretch and hit the bathroom. Put a timer onscreen. Most search engines allow you to enter “5 minute timer” and produce that timer for you automatically. Teaching, even remotely, is much more physically active a task than learning so remember your student’s endurance will be less than yours.

Prepare

Create a preflight list to ensure you’ve hit all the setup points before you go live teaching, including testing your camera and microphone and cleaning up your teaching platform. Don’t overshare. Depersonalize your desktop and your workspace.

Where possible, use a second unshared screen for teaching notes, outlines, and coordination. It’s far easier to lose track of time and go on tangents in a remote classroom because of the immediacy of the face-to-face conversation. Make sure you know what time it is, and what you have to cover in your lesson plan.

Have on hand a list of teaching objectives, scripts for live coding demos, working and starting code configurations. Don’t forget wrap-ups, next steps, and so forth. If you can, rehearse before you teach.

  • GitHub Place shareable starting source on GitHub or another publicly available site so students can follow along with minimal setup time. I use GitHub’s gist a lot.
  • Snippetty: Minimize typing with Snippetty. This menu-bar-sourced utility collects, orders, and offers the code or text snippets you’ll need during your session. Snippetty also lets you add presenter notes to those snippets. The less you type directly, the fewer typos you’ll encounter directly, and you limit long pauses during your lesson.
  • Snippety is end-of-life’d, sadly. I love this tool.

Display Tools

When displaying slides, whether from a second screen or a tablet, use the presenter notes feature to remind yourself of important topics.

A highlighting tool such as ScreenBrush (ScreenBrush for Mac and ScreenBrush for iOS) is great for circling, underlining, and drawing arrows to onscreen information.

I’m particularly fond of LargeType from Gold Mountain Software, which enables you to emphasize text or code at a readable huge size. This is a great way to call out key information. I’ve customized System Preferences > Keyboard > Shortcuts > Services > Text > LargeType to add a custom keyboard combination to perform selection enlargement without using menus. I currently have it set to Command-Control-Option-L, but you can pick whatever keyboard shortcut best works for you.

Don’t forget that your screen will be hard to read. macOS’s accessibility features enable you to use the mouse, trackpad, and keyboard to zoom parts of the screen. This allows you to zoom in on code and other important details that could be missed by showing an entire large screen. The zoom centers around your cursor by default, so it tracks your interest point and allows that field of vision to be shared with others. Visit System Preferences > Accessibility > Zoom to set your preferences

Demoing

Reflector 3 wirelessly mirrors an iOS screen, enabling you to load, launch, and demo apps from your deployment device. I also use Reflector 3 as a wireless screen-mirroring app from my iOS device.

If you don’t mind being tethered, QuickTime allows you to present your device screen for a connected iOS device.

Whiteboarding

On my iPad, I use Linea Sketchto draw. It has a present mode that hides all the normal iOS app details and just shows a plain whiteboard drawing screen. I recently upgraded to a lastest-gen iPad mini with 1st gen pencil and that has been fantastic. I also got good results before my upgrade with the rubber tipped Heiyo stylus. Use a firm stylus for writing. Most stylii are designed for drawing and to simulate brushes.  The Heiyo doesn’t scratch the screen like the metal-tipped ones, is easy to charge (microUSB), and works with older iPads.

Zoom

Zoom offers a number of great built-in features for questions, messaging, raising hands, and so forth. I particularly like using it to know when students are done with a particular task: clear the participant list and have them use a check mark or thumbs up when they have finished. This way you can continue the class without having to wait a full number of minutes.

The same tool is great for “Who thinks that X is Y” style questions. Always encourage the student to answer before looking at what others have voted.

If you can, supplement Zoom with Slack. It’s much better for creating a record of q&a (start a thread specifically for that), and for when you need to distribute text/code from teacher to students. In terms of q&a, a great approach is to allow 3-5 minutes where everyone can add their questions and then you review the questions and choose which ones you wish to answer. I got this technique from Andrew Madsen and it’s terrific. He also recommends using sli.do for audience participation.

How to contribute to the iOS Developer Survey

Dave Verwer, bless his heart, put together an amazing collection of developer statistics in this year’s iOS developer survey. From careers to conferences, dev tools to frameworks, he profiled the community to discover what is happening on our platforms and in our jobs. If you haven’t already been over to the survey site, go and click the link. Don’t worry, this post will still be here when you get back.

The raw data only goes so far. What the survey needs now is you. Dave is looking for community members to help analyze the results so we can better understand what all this data means. For example, we’ve come to love and cherish our dev tools in a way that was unthinkable just a few years ago. Are the high marks for Xcode universal or are  coders with, say, five or more years of development experience particularly grateful for this advancement?

If you have an interest in deeper analysis, Dave has tools to help you slice, dice, and Julian fry the results. Right now there are just four articles available that evaluate the core information (“Is WWDC already a virtual conference?”, “How popular is Swift?”), and they’ve been written by Dave himself.

This data is crying out for deeper investigation, more voices, and diverse insights. If you have time and curiosity, I urge you to reach out to Dave on Twitter and get involved.

This is a fantastic opportunity to give a little back to the community that nurtures our professional lives.

How to fix: Ooops, I lost track of those beta upgrades

What happens when you put off beta upgrades and put them off and off and off and suddenly the release version has outpaced the beta? This happens:

And this happens:

So there you are, stuck in beta and complaining to your friends about what is, ultimate, my your fault. If you don’t update on a timely basis, you can waste a few hours (as I just did) getting your system back on track so you can mess with (for example, just to pull something out of thin air) Swift Playgrounds for iOS for Mac (which requires the 10.15.4 beta10.15.3).

Just so you don’t waste time, don’t try installing the 10.15.3 combo updater. (Image above) You need to:

  • Unenroll from the beta program,
  • Install the latest macos from the App Store,
  • Re-enroll into the beta program, and
  • Upgrade to the latest beta.

Prepare to waste your entire morning on this, hopefully less the time I spent figuring it out courtesy of friends. Once you get the App Store blessed macos install going, remember that once it reboots, there’s another hour of wait time just on the standard install:

Those 13 minutes are a lie.

Expect at least another hour once you get to the beta access installer:

Hopefully this post will help anyone doing a websearch to get out of exactly this issue at some point in the future.

A final note: Once you’re up to date, swear to yourself that your rule of “never be the first to install a new beta” doesn’t mean “never be the last to install the new beta“. Hopefully I’ve learned my lesson.

Adjusting HDMI volume on Catalina

Normally when you output audio through HDMI, you cannot control its volume from your Mac. You adjust it on the output device instead, whether it is a monitor or TV.

I’m working on my Catalina laptop while my mini is in the shop and using my newish DELL monitor without my normal speakers, which plug into the headphone jacks. With this setup, my music is loud, even when I have the monitor settings fairly low.

As it is a pain to adjust volume through the monitor menu, I decided to give Soundflower/SoundflowerBed a try. I was quite sure that Catalina would have killed it by now.

I was wrong.

In SoundflowerBed, I chose HDMI for the 2-channel output.

In System Preferences, I selected Soundflower (2ch) as my sound output device.

Boom. My volume control came back to life and my ears are recovering from the onslaught.

Seeing an old friend keep plugging along and doing what I need is remarkably satisfying. Thank you to everyone who has worked on Soundflower through the years, from Alexander Hudek and RogueAmoeba to MattIngalls and Maciej Wilczyński.

Circles within circles: custom types and extensions

So the other day Paul and I were shooting the breeze about spirographs. He was saying I needed to get back to blogging now that I have the time. Of course, the second you set out to try to write a post, so many ideas flow forth at once, it actually is hard to pick just one and focus on it. Since he had enjoyed my drawing work, I thought I’d start out with a little push at circles.

That quickly went out of control because I ended up with enough material for a few chapters rather than a single blog post. (And, no, my chapter for his book is about property wrappers, which I love, rather than drawing)

To give a little context, before I decided to try my hand at full time work, I had had a contract with Pragmatic to update my Drawing book. I had to cancel that because commuting full time to another city left me with zero free time for my self, my family, let alone writing. (Now that I am back at my own desk, I may see about returning to that project because geometry is a core passion.)

Anyway, let me start at the end of all this and show you some pictures and then I’ll (pardon me) circle back and start telling the story of the code and how all this came to pass.

I started my day by opening a playground, deciding to just flex my coding and see where it would take me. I wanted to work with circles, so I plugged a range into a map to get me there.

// Get some points around a circle
let points = (0 ..< nPoints).map({ idx -> CGPoint in
  let theta = CGFloat(idx) * (CGFloat.pi * 2 / CGFloat(nPoints))
  return CGPoint(x: r * cos(theta), y: r * sin(theta))
})

// Create a path
let path = UIBezierPath()

// Get the last point before the circle starts again
let lastIndex = points.index(before: points.endIndex)

// Draw something interesting
for (point, index) in zip(points, points.indices) {
  let p0 =  index == lastIndex
    ? points.startIndex
    : points.index(after: index)
  let p1 = index == points.startIndex
    ? lastIndex
    : points.index(before: index)
  path.move(to: .zero)
  path.addCurve(to: point, controlPoint1: points[p0], controlPoint2: points[p1])
  
}

It’s not the worst code in the world, but it’s not great. I was rewarded with a pretty path, so whee. Still, the code was screaming out that it wanted to be better.

I started by attacking the index work. Why not have an array that supported circular indexing by offering the next and previous items? So I built this:

public extension Array {
  /// Return the next element in a circular array
  subscript(progressing idx: Index) -> Element {
    idx == indices.index(before: indices.endIndex)
      ? self[indices.startIndex]
      : self[indices.index(after: idx)]
  }
  
  /// Return the previous element in a circular array
  subscript(regressing idx: Index) -> Element {
    idx == indices.startIndex
      ? self[indices.index(before: indices.endIndex)]
      : self[indices.index(before: idx)]
  }
}

Before you start yelling at me, I quickly realized that this was pretty pointless. Arrays use Int indexing and I had already written wrapping indices a billion times before. Just because I has the concept of a circle in my head didn’t mean that my array needed to. I pulled back and rewrote this to a variation of my wrap:

public extension Array {
  /// Return an offset element in a circular array
  subscript(offsetting idx: Index, by offset: Int) -> Element {
    return self[(((idx + offset) % count) + count) % count]
  }
}

Much shorter, a bit wordy, but you can offset in either direction for as far as you need to go. I did run into a few out of bounds errors before remembering that modulo can return negative values. I decided not to add in any assertions about whether idx was a valid index as arrays already trap on that, so a precondition or assertion was just overkill.

Next, I decided to design a PointCircle, a type made up of points in a circle. Although I initially assumed I’d want a struct, I soon realized that I preferred to be able to tweak a circle’s radius or center, so I moved it to a class instead:

/// A circle of points with a known center and radius
public class PointCircle {
  
  /// Points representing the circle
  public private(set) var points: [CGPoint] = []
  
  /// The number of points along the edge of the circle
  public var count: Int {
    didSet { setPoints() }
  }
  
  /// The circle radius
  public var radius: CGFloat {
    didSet { setPoints() }
  }
  
  /// The circle's center point
  public var center: CGPoint {
    didSet { setPoints() }
  }
  
  public init(count: Int, radius: CGFloat, center: CGPoint = .zero) {
    (self.count, self.radius, self.center) = (count, radius, center)
    setPoints()
  }

  /// Calculate the points based on the center, radius, and point count
  private func setPoints() {
    points = (0 ..< count).map({ idx -> CGPoint in
      let theta = CGFloat(idx) * (2 * CGFloat.pi / CGFloat(count))
      return CGPoint(x: center.x + radius * cos(theta), y: center.y + radius * sin(theta))
    })
  }
  
}

I added observers to each of the tweakable properties (the radius, point count, and center), so the circle points would update whenever these were changed. By the way, this is a great example of when not to use property wrappers. Wrappers establish behavioral declarations, which this is not. My circle uses the observers instead to maintain coherence of its internal state, not to modify, limit, or expand type side effects for any of these properties.

Now I could easily create a circle and play with its points:

let circle = PointCircle(count: 20, radius: 100)
let path = UIBezierPath()
for (point, index) in zip(circle.points, circle.points.indices) {
  path.move(to: circle.center)
  path.addCurve(to: point,
                controlPoint1: circle.points[offsetting: index, by: 1],
                controlPoint2: circle.points[offsetting: index, by: -1])
}

I decided not to add some kind of API for passing a 2-argument (point, index) closure to my circle instance. It doesn’t really add anything or make much sense to do that here. It wouldn’t produce much beyond a simple for-loop, and the point here is to build a Bezier path, not to “process” the circle points.

My goal was to build enough support to allow me to iterate through the points and reference adjacent (or further offset) points to build curves. This does the job quite nicely.

It didn’t feel quite finished though. I wanted to add a little extra because one of the things I often do with this kind of drawing is create stars and points and loops using offsets from the main radius, often interpolated between the main points on the circle’s edge. Because I had built such a simple class, adding an extension for this was a snap:

extension PointCircle {
  /// Returns an interpolated point after a given index.
  ///
  /// - Note: Cannot pass the existing radius as a default, which is why the greatest finite magnitude is used
  public func interpolatedPoint(after idx: Int, offsetBy offset: CGFloat = 0.5, radius r: CGFloat = .greatestFiniteMagnitude) -> CGPoint {
    let r = r == .greatestFiniteMagnitude ? self.radius : r
    let theta = (CGFloat(idx) + offset) * (2 * CGFloat.pi / CGFloat(count))
    return CGPoint(x: center.x + r * cos(theta), y: center.y + r * sin(theta))
  }
}

The most interesting thing about this is that you cannot use a type member to default a method argument, which is why I ended up defaulting it to `greatestFiniteMagnitude`. It seems to me that it would be a natural fit for the Swift language to allow that kind of defaulting. In this case, it would say: “If the caller doesn’t specify a radius, just use the one already defined by the instance.” What do you think? Is that too weird an ask?

To wrap up, here’s an example using the interpolation:

let path2 = UIBezierPath()
for (point, index) in zip(circle.points, circle.points.indices) {
  path2.move(to: point)
  path2.addCurve(to: circle.points[offsetting: index, by: 1],
                 controlPoint1: circle.interpolatedPoint(after: index, offsetBy: 0.33, radius: circle.radius * -2),
                 controlPoint2: circle.interpolatedPoint(after: index, offsetBy: 0.67, radius: circle.radius * -2))
}

All the shapes at the start of this post are created from this and the preceding loop by tweaking the curve parameters. What pretty results will you come up with? If you build something particularly lovely, please share. I’d love to see them!

Reading stdin on the fly

Shai Mishali asks, “Is there something like readLine that lets me read stdin as the user types instead of waiting for an entire line?” The readLine function waits until the user presses enter or otherwise recognizes EOF to process input.

A little web search led me to this SO post, which is  based on this example, using termios, the Unix API for terminal I/O. After looking through both posts, I built a RawMode type to support direct input based on that code because nothing makes me happier than messing with solutions to make them a little swiftier.

To use this, you fetch bytes until you catch an EOF. It’s interesting to test both direct keyboard entries as well as pasting complex emojis. As I was working on this on both 10.14 and 10.15, I was mildly startled when my initial test code stopped working when I moved to 10.14. UnicodeScalar does not offer a utf8 view until 10.15:

extension Unicode.Scalar {
  @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
  @frozen
  public struct UTF8View {
    @inlinable
    internal init(value: Unicode.Scalar) {
      self.value = value
    }
    @usableFromInline
    internal var value: Unicode.Scalar
  }

  @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
  @inlinable
  public var utf8: UTF8View { return UTF8View(value: self) }
}

So thank you, Swift team, for giving us that. It’s a nice addition to the language!

Anyway, if you have a different approach or you can see ways to improve my take further, drop a comment and let me know.