“You guys are incredible! I can’t wait to share about it.” That feedback from an early adopter of the new Unsplash iOS app is enough to make developer Olivier Collet’s heart sing. Unsplash, which lets users download free high-quality photos that they can use for anything, with or without crediting the photographer, is big with bloggers, marketers, graphic and web designers. Now, those designers can work from their Apple mobile devices, downloading and modifying photos as needed. And Collet no longer has to worry about whether users of the slick photo downloading site will be disappointed.

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Collet has spent a lot of time in his career thinking about how to make users happy. Originally from France, he started working as a fulltime iOS developer in 2009. He worked with a number of local companies including WhereCloud, PasswordBox and Edovia before splitting time between Los Angeles and Montreal with Match.com. He also co-organized CocoaHeads, a meetup for iOS and Mac developers in Montreal. Then in February 2017, Collet ran into Unsplash cofounders Mikael Cho and Luke Chesser at the Crew Café. Collet had followed Cho’s pivot to Crew and then Unsplash after Cho had emailed Collet about presenting his new startup Ooomf at CocoaHeads years before. Timing was good, because Unsplash was looking for an iOS dev and Collet was looking for a job.

So Collet signed up. His first release was an iOS-only photo upload app followed by an Android and Mac wallpaper app where users wake up to a new Unsplash photo as their wallpaper every day. The latter has been featured on the Apple App Store.

But when Unsplash hired Collet to make an app, they weren’t thinking just about wallpaper. “Our strategy for native apps was (is) to create and release small apps that put the spotlight on the beautiful photos you can find on Unsplash, and see the ones that stick,” wrote Collet in a blog post. They also didn’t want to just replicate the website, since they figured that the creative use cases would be different on desktop and mobile.

So after launching the wallpaper app, Collet went back to work on a productivity app for users like Kunz, who uses Unsplash photos in his typography work. “You’ve just streamlined my life,” wrote Kunz in an email to the company, employing a lot of caps to explain how glad he is to save time while importing and selecting pictures.

One of Kunz’s favourite features is the drag-and-drop function to move photos between apps and to save them, which Collet says was the most important criteria that he and his colleagues had in mind when designing the app. “When Apple showcased iOS 11 at its developer conference last June, I thought it was really cool on iPad,” said Collet in an interview with Montreal in Technology. “You could drag an item from one app to another app to share content. We all thought it would be great for Unsplash photos to share to other apps. That’s the prototype I started in July, 2017.”

But the path to launch is rarely smooth, and Collet says that sometimes you need to take a step back and rethink your product. “At the end of October, we had a version that we were about to release with tabs for photos, collections, search – it felt a little bit more like the website. It was kind of overwhelming. You had too much content in too many places. It was good, but it lacked the ‘wow’ factor, so we decided to simplify everything on one screen.”

That meant months more development, which equated to more time for self-doubt. “After you work so long on the product without shipping, without feedback from people, you start to worry about how people will react,” said Collet. Fortunately, he now knows that he didn’t waste his time. And he’s happy that he didn’t ship a product that users don’t like.

While Collet is happy that users are happy, he admits that there were some embarrassing issues to fix. In the release notes for the latest update, he quotes the founder of LinkedIn, who said: “If you’re not embarrassed by the first version of your product, you’re shipping too late.”

One issue he’s still working on is the custom transition that lets users tap a photo to view it full screen, then scroll left/right to view more photos. “The challenge is that when you go back to the photo grid, you may go back to a photo that wasn’t visible when you left the grid in the first place. The grid has to scroll to the correct offset so that the transition looks good. While it’s okay, I’m still unhappy with that custom transition,” he admits. “I’m working on it.”

From a technical standpoint, the biggest challenge was the home screen. “When you open the app you don’t have tabs or menus,” said Collet. “You just have search, collections and new photos. You have access to everything we have to show in the app. It’s the same content on iPhone and iPad, but it’s displayed differently on iPad. You can adjust the width of the app, especially on iPad when you have split screen, and we have several use cases for different layouts. And when you rotate the device, it changes again. Handling all those layout variations was complicated.”

Other technical challenges included smoothing out the scrolling for the photo grid to remove ‘hiccups’ and banding. “To fix this, I first had to improve the way the photos are loaded and cached,” he said. “Caching images consists of saving them temporarily on the device, to avoid fetching them again from the site every time we display them. It makes the app feel faster and saves a lot of data on users’ data plans.”

While image caching is common practice and there are pre-existing libraries of code for it, Collet preferred to write a custom cache for the images. “I hate using dependencies in my projects,” he said. He also wanted to replicate the ‘waterfall’ layout of the website and ended up writing custom code for that, as well. “It took a bit of time to optimize,” he says.

A fun and cool challenge, said Collet, was the download circle that appears in the bottom left corner when you drag a photo. “The progress indicator was tricky. I had to use the Pythagorean theorem to calculate the start and end points – something I hadn’t used since high school!”

Collet is quick to admit that one of the best things about working on Unsplash is working with a strong team. It was a collaborative decision to leave social features out of the app, he said. “It doesn’t feel like Instagram, which it might have if it had the social features. When the Unsplash founders met with some people from Apple last January, they liked that we didn’t make a social app, that we made something a little different.” That means no accounts or private photo collection storage – for now.

While Collet collaborates with Unsplash’s two designers on the app, Kirill Zakharov and Charles Deluvio, he’s the only app programmer at the company (though the company is currently hiring a full stack developer as well as a writer and marketing projects lead). His specialty is iOS, but that’s not why he won’t be making an equivalent app for Android any time soon, he said. “We don’t see the same demographics of Android tablet users,” said Collet. “I guess Apple has won the tablet market. Maybe Microsoft Surface is a competitor, but iPad is leading, so it wouldn’t make sense to make something similar on Android.”

What’s next for the app? “We’re going to start soon on photographers’ profiles,” said Collet. “We just started using six-week project cycles. It’s based on an idea from the guys of Basecamp. So user profiles will be end of May. Earlier if we can.”

According to Unsplash Co-founder and CEO Mikael Cho, more than 2,083 Unsplash photos are viewed across the web every second. If even a small percentage of those web users appreciate the app, that’s a lot of positive feedback.