Twitter Nostalgia

December 1st, 2006. Something important in my life began rather inauspiciously:

My first tweet.

Little did I realize that these tweets would become a log of important events in my life. And now thanks to Twitter’s new search capabilities, I can remember that past. Please indulge me as I sift through these moments and get nostalgic…

It turns out I was the sixth person to mention “iPhone” on Twitter. My colleague Corey beat me by a few hours and the guy who started Twitter was first. There must have been something in the water at the Iconfactory water that day. I wish all my predictions on Twitter were so prescient!

(Thanks to Dan Frommer for doing the legwork on this one.)

Interestingly, the very next tweet in my timeline was the start of the world’s first Twitter client:

These two tweets, separated by only a few hours, are an amazing summary of what was about to happen.

But first, another important event transpired: I started writing publicly. Twitter was clearly an inspiration here: I loved those 140 characters, but found that I needed another venue to expand upon my thoughts:

Note the date on that last tweet: the day before the original iPhone went on sale. My first post stated that I didn’t know where there I was going with the blog. A few days later, I had a pretty good idea:

I had just bought an iPhone.

And remember that “video iPhone nano gaming system”? Here I am being the first person to display a Twitter timeline on it:

Worlds were colliding: Twitter, iPhone, and a place to talk about both.

Twitter was always an outlet for my strange sense of humor. Depending on your point-of-view, April Fool’s in 2008 was either the best or worst day ever:

It’s now commonly known as the CHOCK LOCK, but it took almost five months for someone to christen it:

And amazingly, just six minutes later:

Both Seth and Michael were spurred on by Dan Wood, so I guess we can blame him!

The iPhone SDK was released in February 2008 and a lot of that early hacking I did on the iPhone was finally turning into a real product. It’s likely that this affection with capital letters was triggered by a shitload of coding.

But all that hard work paid off:

I tweeted that just after being handed an Apple Design Award. Those colliding worlds were good to me.

I’m a firm believer of looking forward in your work, but there’s also value in remembering how you got to where you are today.

And speaking of today, guess when the bulk of this post was written?

Some things never change.

A day with Apple Watch

As every Apple developer knows by now, Apple Watch is becoming a reality. If you do nothing else right now, watch the video at that link: it’s a great overview of WatchKit that will only take a half hour of your time.

David Smith put it best: there’s a lot more here than most of us expected. I spent yesterday exploring the APIs and have some thoughts and links to share below.

Software Design

The local and remote nature of WKInterfaceObject feels a lot like the days of a dumb terminal talking to a mainframe. Except this time, the terminal ain’t dumb, and the mainframe fits in your pocket.

But still, there’s RPC going on here, and a lot of the design patterns and limitations are due to that fact. Our IBOulets and IBActions are traveling around in thin air: let’s take a look at what that means.

No customization

WKInterfaceObject inherits from NSObject, but don’t let that fool you. There’s absolutely no customization here: you can’t subclass WKInterfaceWhatever.

If you don’t believe me, try to set a Custom Class for one of the objects in Interface Builder. While this is a limitation, it’s also a good thing for a new platform: it forces consistency in the user interface. None of us have even held an Apple Watch before, so constraints will help us to not shoot ourselves in the foot.

One thing that some of us are wondering: why aren’t these classes that can’t be instantiated just protocols? Time will tell, I’m sure.

No properties

In a similar vein, these WKInterfaceObject classes aren’t like other UI objects we’re used to dealing with. There are no @properties, only setters. Why?

Querying a property would mean a round-trip over Bluetooth to get a control’s current state. It’s more efficient for your iPhone app to keep track of things instead of consuming power with a radio.

Object marshaling

When you set a property using an object, you may be fooled into thinking that object goes over the wire.

Look at UIFont in an attributed string, for example. If you try to instantiate one of the San Francisco fonts that you find in the SDK, you’ll be surprised that it returns nil. Remember, you’re creating this instance on an iPhone (where the font doesn’t exist) to use on a watch (where it does exist.)

I’m guessing that things like font instances are marshaled over to the device. At this point, it’s important to remember that an object you create may not be the one used in the user interface.


Images are a large part of what makes a great looking app these days. We’ve gotten pretty good at it. Understanding how they work in WatchKit is essential.

It’s best to make your images static resources in the bundle that gets delivered to the watch. It’s expensive to transfer these large assets over Bluetooth. The best experience for the user is to pay that price at the time the watch app is installed.

To get an idea of the extent of this philosophy, download the Lister sample code and look in the Watch App assets for the Glance UI. You’ll find 360 images: one for each degree of the circle’s movement. Your designer is going to love making these images. j/k LOL

Still, there are cases where you’ll need to send images to the watch dynamically. Think about avatars for a social networking service: no amount of memory can hold all the images you’d need for Twitter.

This confused me at first, so I asked someone who’d know. The solution is to use WKInterfaceDevice to add images by name. These can then be used in WKInterfaceImage using the -setImageNamed: method. The image cache can hold up to 20 MB and is persistent across launches. Think of it as a way to dynamically extend the contents of the bundle you delivered during the install process.

Another approach is to create the image on the iPhone and transfer it directly to WKInterfaceImage using the -setImage: method. This is reasonably fast in the simulator, but I’ll bet money there’s a significant lag on the actual device.


My first impression of the user interfaces you could design in Interface Builder wasn’t entirely positive. I could create designs that were functional, but I couldn’t personalize the layout. That all changed when I figured out how WKInterfaceGroup worked.

The light went on when I saw that a WKInterfaceButton had a content setting for “Text” and “Group”. When you specify “Group”, you get a container where you can place other items. It was only a matter of time until I ended up with this:


The pretty part is the list of objects on the left, not my abuse on the right!

The topmost “Button” uses the group content mode, so it’s layout is defined with a container. That container includes three more items: another blue button with an “A”, a WKInterfaceTimer that counts down, and an image with the “check-all.png” graphic. The Group container uses a red background with another transparent image (the teal arc.)

The interesting thing here is that while you only get one IBAction for the button, you can set up multiple IBOutlets for the items in the container. As a test, I hooked up the button’s action to change the background color of the group, reset the timer, and swap one of the images.

In Interface Builder, the Size and Position settings in WKInterfaceObject’s Attribute inspector let you define where the items in the container are placed and how much space they should use. Since you don’t know if you’re going to be running on a 38mm or 42mm device, think in fractions. The example above uses 0.25 for the button and the timer, and 0.5 for the image.

Power Consumption

Bluetooth Low Energy must be really low power: the design of WKInterfaceObject means it’s going to be on a lot. Every interaction with the watch has the potential to move actions and data between your pocket and wrist using the radio.

But more importantly, this API design gives Apple a simple way to put a cap on power consumption. We saw this approach in the early days of the iPhone and that worked out pretty well, didn’t it?

One final thought about the API design: your code never runs on the watch.

Physical Design

In addition to new APIs, more information about the physical characteristics of the watch have been made available. We now know that the 42mm model has a 312×390 pixel display and that its 38mm counterpart uses 272×340 pixels.

Screen resolution

In addition to its size, the placement of the display on the face of the watch has been documented in the layout section of the Human Interface Guidelines. That has led some of us to estimate the screen resolution.

My calculations put the resolution somewhere above 300 ppi:


Since we’re not dealing with engineering drawings here, it’s impossible to be precise. For one thing, we don’t know where Apple is measuring 38 and 42 millimeters. Traditionally, it’s measured from the center of the lugs, but since the Apple Watch uses a different mechanism, it could be the size of the sapphire crystal.

John Gruber, who has a stellar record at this guessing game, thinks the display will be 326 ppi, just like on the iPhone 6.

But you’ve got bigger problems than pixel perfect design now anyway…

Screen size

The display layout drawings give us enough information to create a reasonable physical facsimile of the watch.

It’s small. Very small.

Much smaller than you think if you’ve been looking at it in the simulator.

You’ll want to download this PDF created by Thibaut Sailly and print it out at 100%. My first thoughts were that my finger covered more than half the screen and that I could fit eight of these displays on my iPhone 6!

After this “physical contact” with the Apple Watch, some of the controls that we see in the simulator feel ridiculously small. There’s no way you’re going to tap the back arrow in the nav controller with your finger: I’m guessing that control is there solely for developers who are using mice and trackpads to develop their apps.


Once you have the PDF to give you an idea of the physical size, you can then start to see how your design works at that scale. Thibaut has already made the world’s ugliest watch and it’s doing important information design work. Here it is showing a simulated scroll view and exploring glance interactions.

You can even take these mockups a step further and strap a phone to your wrist. While it may look and feel a bit strange, there are definitely some interesting insights being discovered in that Dribbble post. The Mirror tool in xScope could be very handy for this kind of work: design in Photoshop, view on your wrist and learn.

These physical interactions with your designs are incredibly important at this point. Wondering why the scroll indicator only appears in the upper-right corner while you scroll your view? I was until I realized that’s where the digital crown is physically located.


One thing that none of us are going to miss in WatchKit: you don’t have to worry about device orientation changes.

As my friend, and party pooper, John Siracusa points out, this is probably just a temporary situation. As a fashion accessory, Apple Watch could easily become a pendant watch.

Where to go from here

So there you have it: a day spent with another revolutionary set of APIs. If you’re just starting out, the links to the HIG and sample code above are great places to start learning.

If design interests you as much as code, you’ll also want to download the Apple Watch Design Resources (the link is at the bottom of that page.) You’ll find all the fonts and Photoshop documents you need to start pushing pixels. But as you saw above, make every effort to put those pixels into physical perspective.

As Apple has stated, this is only the initial phase of the API rollout: fully native apps will be possible later this year. Even though this is a first step, it’s a really good one.

All that’s left to do now is start making awesome apps.


Behind The App: Flare 2

Here’s what I’ve been pouring my heart and soul into since the day WWDC 2014 ended: Flare 2.

We started working on this project well before WWDC. A significant redesign that put content first had been completed. A lot of code had been written and the app was working well.


WWDC was a cornucopia for developers. There were suddenly so many new things we could do on both iOS and OS X. It was overwhelming and exciting at the same time.


Three things stood out for us: the new look for Yosemite, iOS 8 extensions, and CloudKit. We had always wanted to do something with Flare that needed these things. It really felt like we won the Apple developer lottery.

We could now create great photographic effects on our Macs and apply them to the photos taken with the camera that’s in our pocket. Perfect. Simple.

But even with a simple and perfect goal, execution is never easy. I think there’s always a lot to learn by looking back at the struggles you encounter during product development, so here are some things Anthony, Talos, Travis, Wolfgang, Sean and I encountered during our journey.

Yosemite’s User Interface

The Flattening

As I noted above, we’re acutely aware of the direction that OS X and iOS user interfaces are heading. We’ve been striving to put content first for a couple of years now. This effort started with Twitterrific 5.

Note the date of the post in that last link: December 2012 was six months prior to iOS 7 and “flat user interfaces” being announced at WWDC 2013. While everyone else was making interfaces like the one on the left, we created the one on the right:


Click on the image to see a bigger version

We saw the same opportunity to simplify Flare. It was possible to create an app that put the customer’s content frontmost while retaining advanced controls to adjust the photo when needed.

This is where we were at on May 28th of this year. Anthony’s mockup was already very flat and content-centric:


Of course, after WWDC we realize we could do even more to simplify the user interface. Here’s how the final product turned out:


(If you’re at all interested in interface design, I suggest downloading a copy of Flare just to try it out. There are a lot of animations and other effects that can’t be expressed in static screenshots.)

As a company, designing and implementing a user interface for Yosemite is a very important exercise. We have clients who want us to help move their apps in a similar direction, and the only way to become an expert with this stuff is by making it.

Here are a few observations from the “Yosemitification” of Flare. (And yes, we used “Yosemitify” frequently in our internal discussions!)

Tint & Themes

The influence of iOS 8 goes beyond the flatness of the design. We wanted to use control tint color to give the user feedback on the state of the application. The tint color also gave us a visual anchor between the two platforms were Flare runs: the purple tint links the user interfaces on iOS and OS X.

Unfortunately, OS X only supports the notion of two tints: blue or graphite. In the end, we wrote our own control cell classes that used a custom tint color. I’m hoping to have the time to open source this code some day: many products besides ours are embracing multiple platforms and these controls will be very helpful to other developers.

Another subtle touch in the Flare user interface: it supports both the light and dark themes in Yosemite. The theme support in Yosemite allows you to change the entire control hierarchy’s appearance at any time. We use this capability as another way to put the customer’s content first: sometimes their photos look best on a black background, other times a white background.


There was a very common theme throughout Flare’s development. We would add vibrancy to the interface, and then a couple of weeks later, we’d remove it.

Personally, I think it’s a lovely and subtle effect. But it’s just too easy to use it in a way that interferes with usability. Text and other lightly stroked information (such as icons) can disappear on the subtly colored gradients that you have little control over.

The last vibrant holdout in Flare was the header at the top of the list of effects. In fact, we removed it the day before the app was submitted for review! The thumbnail images looked really cool sliding up underneath a transparent header, but since we don’t have control of the content generated by the thumbnails, it was much too easy to have colors that rendered the icons and text unreadable.

(In the screenshot above, you will notice a slight color shift between the header and the thumbnail content that’s not in the final product: the screenshot was created before we removed the visual effects view.)

Vibrancy does still have a place in our app. It works great in the “guided tour” for displaying help over the content and controls of the interface. This guided tour is also a piece of UI that we’re all very proud of: we wish we could sit down with every customer and say “Hey, look at this!”, but this tour is a really great alternative.

iOS 8 Extensions


Let’s just say things were a little rough development-wise at the beginning. Extensions are an awesome addition to both OS X and iOS, but as with anything new, they were also fragile. At one point, the only debugging tool was my old friend printf(). Not having Instruments available to track down memory leaks makes you appreciate the awesome power of that tool.

As new versions of Xcode came out during the iOS 8 beta, the situation improved steadily. This is why they call it the “bleeding edge.” I just want to know why I always forget this when starting out with something new and shiny :-)

I’ll have some more to say about these tools in the very near future: I’m working on a field guide for iOS extension development.


As someone who developed an app on the original iPhone using iOS 2.0, I didn’t think there would ever again be so many problems with managing memory. I was wrong.

Creating the Photos Extensions in Flare Effects was a huge challenge. First off, the most recent cameras have very high resolution. For example, the native size on my iPhone 6 is 2448 x 3264 pixels. That’s over 20 MB of source data you need to deal with.

These big images are being handled in an XPC process that runs at the same time as the Photos or Camera processes. You’re not the only one who’s dealing with a lot of pixels.

Compounding this is the fact that you usually need several of these big images around for compositing and other effects. Luckily, a lot of the magic in Flare (and iOS 8 in general) is done with Core Image, so a lot of the heavy memory requirements can be offloaded to the GPU via OpenGL ES. But even then, you have to be very careful: a post on Stack Overflow about managing textures across thread boundaries, literally saved our ass. I owe Max a beer.

Wolfgang did some amazing work to get our very complex filters running smoothly on iOS. Despite the APIs for Core Image being nearly identical between OS X and iOS, the data and parameters you feed the filters have very different requirements. Textures, scaling factors, extents and many other things had to be adjusted for the new platform!

The situation with memory was a constant struggle. In fact, it was even an issue after we had the app approved and ready for sale. We discovered a crashing bug that only happened on the iPhone 6 Plus because it needed a @3x preview image that weighed in at over 20 MB! Rejecting a binary and resubmitting for review the day before an Apple Event is not for the faint of heart.


As developers we often complained about the opaqueness of iCloud. Things would happen and you’d have no idea what was going on behind the scenes.

With CloudKit, that all changed. We’re now responsible for every little thing. Every response, every error, every piece of data. That’s a good thing, but the age-old fact remains: syncing is hard.

Luckily, my colleague Sean likes hard problems and built a syncing system that “just works”. Even then, we’re a little afraid we haven’t covered all the bases: just before submitting the app for review, we discovered an issue where expired tokens weren’t being handled correctly (because we’d switched from the development servers to the production servers.) To be honest here, our fingers are still crossed as we deploy this to millions of potential customers.

Still, the flexibility and breadth of this new API makes it all worthwhile. It makes it possible for us to get cool and free photo effects to folks on iOS even if they don’t use our Mac product. Doing something like that prior to iOS 8 and CloudKit would have been cost prohibitive from an infrastructure point-of-view.


So there you have it, a roundup of all the fun stuff that went into making Flare 2. We hope you enjoy it!

Device Log Douche

The new Devices window in Xcode 6 has been a constant source of grief for the past few months. Getting device logs was an exercise in frustration which usually resulted in me admitting defeat (and without my logs.)

Over the weekend, I found a 2.21 GB answer:


I’ve been developing iOS apps since the beginning of time. I had over 7,000 crash logs in my ~/Library/Developer/Xcode/iOS Device Logs folder! Every time I opened the new Devices window Xcode would tell me it processing some very old crash logs: at one point I saw one from 2008 go by! All this useless work prevented me from getting to the most recent reports.

It appears that newer versions of Xcode store the crash reports in a Core Data SQLite database. Both the raw and symbolicated reports are kept in the iOS Device Logs folder:

$ sqlite3 "iOS Device Logs 6.0.1.db"
sqlite> select count(*) from zrawlogtext;
sqlite> select count(*) from zlogtext;

I first tried removing all the old .crash files. Xcode still insisted on processing, so it must be working on stuff already captured in the SQLite database. When I removed the most recent database, I was greeted with an Xcode hang after clicking on the “View Device Logs” button.

A spindump showed that Xcode’s DTDKCrashLogDatabase class was doing a -performBlockAndWait: on the main thread. I’m guessing that Xcode was trying to copy over databases from previous versions as some kind of migration process.

In the end, I removed everything in the iOS Device Logs folder and can now use the Devices window as it was intended.

Note for Apple folks: A Radar with the spindump is here: rdar://18489861.

In-App Browsers Considered Harmful

How many apps on your iPhone or iPad have a built-in browser?

Would it surprise you to know that every one of those apps could eavesdrop on your typing? Even when it’s in a secure login screen with a password field?

Here is a proof-of-concept (ZIP file) that shows how an app can do this. For those of you who don’t have Xcode installed, here’s a video that shows what’s going on:

A few things to note about what you’re seeing:

  • The information at the top of the screen is generated by the app, not the web page. This information could easily be uploaded to remote server.
  • This is not phishing: the site shown is the actual Twitter website. This technique can be applied to any site that has a input form. All the attacker needs to know can easily be obtained by viewing the public facing HTML on the site.
  • The app is stealing your username and password by watching what you type on the site. There’s nothing the site owner can do about this, since the web view has control over JavaScript that runs in the browser.
  • The site content is also modified: the text on the button label is normally “Sign in” and has been changed to “SUCK IT UP”. It seemed appropriate.
  • This technique works in iOS 7 and 8 (and probably earlier versions, but I didn’t have an easy way to test them.)


No, this is not a WebKit bug.

The Shadow DOM does a great job of protecting static user content on a web page. It’s not possible to use JavaScript to view the contents of an input field on iOS since the current value attribute is actually being held in a platform-native control. The value of that control is uploaded when the user submits a <form>.

I don’t know for sure, but I suspect that the keyCode attribute of the KeyboardEvent in the JavaScript event handler is provided for backward compatibility. This API has been deprecated but there are still plenty of web pages out there that use it to handle keyboard input.

In fact, both the techniques shown in the sample app can be used for good as well as evil. Changing the content of a web page is a good thing when it’s done to make a page more readable or accessible. Handling keyboard events can also guide a user through a complex form or make viewing a slide show easier.

These are not inherently bad web technologies. The problem is that an iOS app has as much access to these technologies as the developer of the web page.

OAuth To The Rescue. Or Not.

Websites have been dealing with username and password attacks for as long as there have been <input> fields on their pages. One of the primary goals of OAuth was to keep a user’s login information away from an external website or app.

OAuth does this by exchanging cryptographically signed tokens between the site where the user has an account and the app or web service that wants to access that account. A key factor in making this secure is that the exchange of these secure tokens is done through a trusted channel: the user’s web browser. Twitter has required third-party developers to use OAuth since 2010.

As early as 2008, the developers of OAuth recommended the following:

We’re trying to ensure that users are only exposed to the safest way to disclose their location using OAuth. To do this, it’s critical that a fundamental principal of browser-based authentication is followed; that the contexts of the third party application and the web service authentication remain separate. To allow users to grant trust to an application, they must perform the OAuth action within their web browser, not within the applications themselves. Otherwise, there is no way to verify the identity and authenticity of any page which asks for their username and password. Users must not ever enter their username and password into a third party application when a browser-based authentication API like OAuth is available.

There is always a tradeoff between usability and security. Doing the OAuth token exchange with an in-app browser makes it easier for a user to login, but they’ll have no idea if their personal information was captured. That is why Twitterrific did its token exchange in Safari, even though it’s a more complex user interaction and a more difficult technical implementation. As a user, I know that there’s no way for my login to be compromised when the transaction involves Safari.

Unfortunately, Apple’s current App Review policy does not agree with this recommendation or with Twittterrific’s previous implementation. This is why our update for iOS 8 was delayed—it was the first time since the launch of the App Store that we haven’t had a new version on release day.

(Apple folks can learn more about this situation by reviewing Radar #18419943)

Recommendations for Apple

Apple has taken a strong and welcome stance on privacy. They’ve recently been implicated in some high profile attacks so they definitely have skin in this game. Hell, they even want to protect us from the US government watching what we do online!

There’s no denying that the behavior demonstrated above could be very harmful in the wrong hands. It’s also Apple’s job as the gatekeeper for iOS to keep malicious apps out of the App Store. But how?

I don’t think it’s feasible to catch misbehaving apps at review time. There are a huge number of apps that need to be reviewed every day, especially when new versions of iOS are released. Many of these apps use in-app browsers which would require extra time and effort to vet. Longer review times benefit no one: developers, Apple and our customers need timely updates.

It’s also very easy to an app to hide any nefarious activity. JavaScript has an eval() function that makes it easy for code to be obfuscated and very difficult to be checked at review time. Look at this page and see if you can guess how the uppercase text was created. Then view the HTML source and see how wrong you were.

Additionally, an app that wants to collect your information can easily implement a remote switch that disables the functionality while the app is in review. App reviewers won’t stand a chance.

Changing how WebKit and UIWebView behave isn’t practical either. To prevent this keylogging technique, Apple would need to release a new version of iOS for each version that included Safari and WebKit. Do you really think they’re going to do a point release of iOS 3?

And this brings me back to protecting users with OAuth. It’s designed to avoid these problems and works well to maintain privacy. Granted, it goes against section 10.6 of the App Store Review Guidelines, but in my opinion, this is a case where user security trumps usability. Apple should change their policy for apps that use OAuth.

Recommendations for Users

Another goal of this essay is to increase user awareness of the potential dangers of using an in-app browser. You should never enter any private information while you’re using an app that’s not Safari.

An in-app browser is a great tool for quickly viewing web content, especially for things like links in Twitterrific’s timeline. But if you should always open a link in Safari if you have any concern that your information might be collected. Safari is the only app on iOS that comes with Apple’s guarantee of security.

(For the record, we never collect any private information in any of the Iconfactory apps. And we never will.)