Pass Data in iOS Apps

Notifications vs Delegates vs Closures vs Key-Value Observation

Photo by Joshua Sortino on Unsplash

Prerequisites:

• You will be expected to be aware how to make a Single View Application in Swift, or be able to code in Swift Playgrounds

Terminology:

Closures: A combination of functions and references to the surrounding context

Delegation: A pattern that enables a class to delegate responsibility for some actions to an instance of another class

NotificationCenter: A notification dispatch mechanism that enables the broadcast of information to registered observers

KVO: (Key-Value Observing), is one of the techniques for observing the program state changes available in Objective-C and Swift

Delegation

I’ve previously written an article on delegation which shows that delegates are a great way of passing information between two loosely-coupled objects.

Pros

• All objects conforming to the protocol must implement those methods
• Easy to understand the program flow
• You can have multiple protocols defined by a single object, each with different delegates