Occasionally an activity within your app requires multiple screens. Consider uploading a photo to Instagram: pick a photo, pick the filter, and add a description. When the user taps a photo in the first screen, it might look like: func userDidPickPhoto(_ photo:Photo){ let filter = FilterViewController() filter.photo = photo navigationController?

From time to time, people ask me how to learn iOS development. So here we go. Before you start, be serious about your goal. Are you trying to prototype a concept, get funding, and then hire someone else to deal with it? Are you a "generalist" who needs

The first time I look at a legacy project, I scan for warning signs. I’ve covered singletons, excessive observers, and today I'll talk about "Manager" classes. I have to reiterate these are guidelines, not rules, and among guidelines, this one isn't critical. A

In my last post, I explained why you should prefer delegates over observers. The former encourages a tree-like data flow, while the latter leads to a cat's cradle. If you're sure you need an observer, Cocoa lets you choose between Notification Center and KVO. Which should

A well structured app consists of simple objects with well-defined responsibilities talking to each other. When you design an object, you might think of an object's properties, and the actions they take, but it's just as important to decide how they'll communicate. Cocoa provides

Singletons are not an anti-pattern, but they are an abused pattern. They're popular among beginners because they're convenient. Down the line they add complexity and cause maddening bugs. Let's start with the positive. Every so often, you have an object that should be represented