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Exploring Declarative UI with SwiftUI in 2020

2020-01-01

On the first day of 2020, I started a new technical exploration: learning SwiftUI. A revolutionary UI framework introduced by Apple at WWDC 2019, it builds user interfaces in an entirely new, declarative way — fundamentally different from the UIKit I was familiar with.

First Look at Declarative Programming

Unlike the imperative programming paradigm of UIKit (telling the system "how to do it"), SwiftUI adopts a declarative paradigm (telling the system "what you want"). We no longer need to worry about the details of view creation, layout, and updates; instead, we "declare" the state and structure of the UI in code, and the framework takes care of the rest. This shift greatly simplifies the code and improves development efficiency.

struct ContentView: View {
    var body: some View {
        Text("Hello, SwiftUI!")
            .font(.title)
            .foregroundColor(.blue)
    }
}

Core Advantages

In my initial learning, I noticed several core advantages of SwiftUI:

  • Concise code: Compared with UIKit, the amount of code is dramatically reduced and the logic is clearer.
  • Live preview: Xcode’s live preview feature is extremely powerful — you can instantly see the effect of code changes, which greatly speeds up UI debugging.
  • Cross-platform: One codebase can run on iOS, iPadOS, macOS, watchOS, and tvOS at the same time — a major step forward in Apple’s ecosystem integration.

Although SwiftUI was still very young in early 2020 and its ecosystem was not yet mature, it represented the future of UI development on Apple platforms. This learning experience opened a door for me to a whole new world of modern UI development.