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@michaelevensen
Last active November 13, 2023 12:20
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A really handy extension to `View` which enables dynamic binding of `GeometryReader` properties like `Size`, `Frame` and `SafeAreaInsets` for a `View`. This is particularly handy when you want to share `GeometryReader` output between other `View`'s. All credit goes to @danielsaidi.
//
// View+Geometry.swift
// SwiftUIKit
//
// Created by Daniel Saidi on 2020-03-26.
// Copyright © 2020 Daniel Saidi. All rights reserved.
//
import SwiftUI
public extension View {
/**
Bind the view's safe area to a binding.
*/
func bindSafeAreaInsets(to binding: Binding<EdgeInsets>) -> some View {
background(safeAreaBindingView(for: binding))
}
/**
Bind the view's size to a binding.
*/
func bindSize(to binding: Binding<CGSize>) -> some View {
background(sizeBindingView(for: binding))
}
/**
Bind the view's frame to a binding.
*/
func bindFrame(to binding: Binding<CGRect>,
coordinateSpace: CoordinateSpace = .global) -> some View {
background(frameBindingView(for: binding, coordinateSpace: coordinateSpace))
}
}
private extension View {
func changeStateAsync(_ action: @escaping () -> Void) {
DispatchQueue.main.async(execute: action)
}
func safeAreaBindingView(for binding: Binding<EdgeInsets>) -> some View {
GeometryReader { geo in
self.safeAreaBindingView(for: binding, geo: geo)
}
}
func safeAreaBindingView(for binding: Binding<EdgeInsets>, geo: GeometryProxy) -> some View {
changeStateAsync { binding.wrappedValue = geo.safeAreaInsets }
return Color.clear
}
func sizeBindingView(for binding: Binding<CGSize>) -> some View {
GeometryReader { geo in
self.sizeBindingView(for: binding, geo: geo)
}
}
func sizeBindingView(for binding: Binding<CGSize>, geo: GeometryProxy) -> some View {
changeStateAsync { binding.wrappedValue = geo.size }
return Color.clear
}
func frameBindingView(for binding: Binding<CGRect>, coordinateSpace: CoordinateSpace = .global) -> some View {
GeometryReader { geo in
self.frameBindingView(for: binding, geo: geo, coordinateSpace: coordinateSpace)
}
}
func frameBindingView(for binding: Binding<CGRect>, geo: GeometryProxy, coordinateSpace: CoordinateSpace) -> some View {
changeStateAsync { binding.wrappedValue = geo.frame(in: coordinateSpace) }
return Color.clear
}
}
@michaelevensen
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michaelevensen commented Jun 26, 2020

And like this if you want to specify CoordinateSpace.

struct GeometryReaderExample: View {
    @State private var stackFrame: CGRect
    
    var body: some View {
        ScrollView {
            HStack {
                ForEach(0..<100) { _ in
                    Text("Some Content..")
                }
            }.bindFrame(to: $stackFrame, coordinateSpace: .local)
        }
    }
}

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