Custom Activity Ring in SwiftUI

Activity rings are a feature of the Apple Watch that track a user’s physical activity throughout the day. There are three rings: one for Move, one for Exercise, and one for Stand. I will create a basic custom activity ring for the beginner and go deep by implementing multi rings.

In this blog post about creating an Activity ring in SwiftUI will cover the following topics:

1. Setting up the basic structure of the ring using the ZStack and Circle views.
2. Creating a custom view modifier to apply the ring’s appearance, such as color and thickness, to the Circle view.
3. Using the animation() method to create an animation for the ring’s progress and a @State variable to track and update the progress.
4. Using the state variable and updating the ring’s progess accordingly.
5. Adding interactivity to the ring, such as the ability to tap or long press and hold to increase the progress.

A Super Basic Custom Activity Ring

Here is an example of how you might create an activity ring in SwiftUI:

struct BasicActivityRing: View {
    @State private var progress: CGFloat = 0.9

    var body: some View {
        ZStack {
            Circle()
                .trim(from: 0, to: progress)
                .stroke(Color.green, style: StrokeStyle(lineWidth: 20, lineCap: .round))
                .frame(width: 200, height: 200)
                .rotationEffect(.degrees(-90))
                .animation(.linear)

            Text("\(Int(progress * 100))%")
                .font(.title)
                .foregroundColor(.green)
        }
        .onTapGesture {
            withAnimation {
                self.progress += 0.01
                if self.progress > 1.01 {
                    self.progress = 0
                }
            }
        }
    }
}

This creates a ring-shaped view using the Circle view, with the trim(from:to:) modifier used to create the appearance of a ring with filled and unfilled sections. The stroke modifier is used to apply a green color and a line width of 20 to the ring. The frame modifier is used to set the size of the ring to 200×200 pixels. The rotationEffect is used to rotate the ring -90 degrees to start the animation from the top.

The Text view is used to display the current progress as a percentage, and the onTapGesture is used to increment the progress by 0.1 on each tap and resets the progress back to zero when it reaches 1.

You can customize this code to match your desired design and desired data.

FastForwardActivityRing: Fast forward with Long press and hold

struct FastForwardActivityRing: View {
    @State private var progress: CGFloat = 0.9
    @State private var timer: Timer?
    @State private var isLongPressAndHold = false

    var body: some View {
        ZStack {
            Circle()
                .trim(from: 0, to: progress)
                .stroke(Color.green, style: StrokeStyle(lineWidth: 20, lineCap: .round))
                .frame(width: 200, height: 200)
                .rotationEffect(.degrees(-90))
                .animation(.linear)

            Text("\(Int(progress * 100))%")
                .font(.title)
                .foregroundColor(.green)
        }
        .onTapGesture {
            withAnimation {
                if isLongPressAndHold {
                    isLongPressAndHold.toggle()
                    timer?.invalidate()
                } else {
                    progress += 0.01
                    if progress > 1.01 {
                        progress = 0
                    }
                }
            }
        }
        .simultaneousGesture(LongPressGesture(minimumDuration: 0.2).onEnded { _ in
            isLongPressAndHold = true
            timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true, block: { _ in
                progress += 0.01
                if progress > 1.01 {
                    progress = 0
                    isLongPressAndHold.toggle()
                    timer?.invalidate()
                }
            })
        })
    }
}

The view has two gesture recognizers to implement press and hold behaviour.

• A onTapGesture that increases the progress by 0.01 when the view is tapped. If the user is currently performing a long press gesture, the gesture recognizer will stop the timer and reset the isLongPressAndHold flag.
• A LongPressGesture that starts a timer when the user performs a long press gesture. The timer increases the progress by 0.01 every 0.1 seconds until the progress reaches 100%. When this happens, the timer is invalidated and the isLongPressAndHold flag is reset.

The code creates a circular progress indicator that can be incremented by tapping on the view or by holding down on the view to increment the progress continuously.

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