Easily read the size of a subview in SwiftUI

Example.swift

struct ExampleView: View {

    // MARK: - Properties
   	@State private var size: CGSize = .zero
    
    // MARK: - Updates
    func body(content: Content) -> some View {
		Text("Size of this label: \(Int(self.size.width)),\(Int(self.size.height))")
            .modifier(SizeModifier({self.size = $0}))
        }
}

SizeModifier.swift

import SwiftUI

struct SizeModifier: ViewModifier {
	
	// MARK: - Properties
	let onSize: (CGSize)->Void
	
	// MARK: - Init
	init(_ onSize: @escaping (CGSize)->Void) {
		self.onSize = onSize
	}
	
	private var sizeView: some View {
		GeometryReader { proxy in
			Color.clear.onAppear {
				self.onSize(proxy.size)
			}.onPreferenceChange(SizePreferenceKey.self) {
				self.onSize($0)
			}
		}
	}
	
	// MARK: - Updates
	func body(content: Content) -> some View {
		content
			.background(self.sizeView)
	}
}

private struct SizePreferenceKey: PreferenceKey {
	
	// MARK: - Properties
	static var defaultValue: CGSize = .zero
	
	// MARK: - Updates
	static func reduce(value: inout CGSize, nextValue: () -> CGSize) {
		value = nextValue()
	}
}