Is it possible to pass the values of GeometryReader to a #Observableobject - swift

Question

I need to do calculations based on the size of the device and the width of a screen.
struct TranslatorView: View {
#ObservedObject var settings = TranslationViewModel(spacing: 4, charSize: 20)
var body: some View {
GeometryReader { geometry in
VStack{
TextField("Enter your name", text:self.$settings.translateString)
}
}
}
}
My ObservableObject can be seen below
class TranslationViewModel: ObservableObject {
#Published var translateString = ""
var ScreenSize : CGFloat = 0
var spacing : CGFloat = 4
var charSize : CGFloat = 20
init(spacing: CGFloat, charSize : CGFloat) {
self.spacing = spacing
self.charSize = charSize
}
}
I need a way to pass the geometry.size.width to my ScreenSize property but have no idea how to do this.

Answer 1

The simplest way is to have setter-method inside the ObservableObject which returns an EmptyView.
import SwiftUI
struct TranslatorView: View {
#ObservedObject var settings = TranslationViewModel(spacing: 4, charSize: 20)
var body: some View {
GeometryReader { geometry in
VStack{
self.settings.passWidth(geometry: geometry)
TextField("Enter your name", text:self.$settings.translateString)
}
}
}
}
class TranslationViewModel: ObservableObject {
#Published var translateString = ""
var ScreenSize : CGFloat = 0
var spacing : CGFloat = 4
var charSize : CGFloat = 20
init(spacing: CGFloat, charSize : CGFloat) {
self.spacing = spacing
self.charSize = charSize
}
func passWidth(geometry: GeometryProxy) -> EmptyView {
self.ScreenSize = geometry.size.width
return EmptyView()
}
}
Then you could implement a wrapper around GeometryReader taking content: () -> Content and a closure which gets executed every time the GeometryReader gets rerendered where you can update whatever you wish.
import SwiftUI
struct TranslatorView: View {
#ObservedObject var settings = TranslationViewModel(spacing: 4, charSize: 20)
var body: some View {
GeometryReaderEasy(callback: {
self.settings.ScreenSize = $0.size.width
}) { geometry in
TextField("Enter your name", text:self.$settings.translateString)
}
}
}
struct GeometryReaderEasy<Content: View>: View {
var callback: (GeometryProxy) -> ()
var content: (GeometryProxy) -> (Content)
private func setGeometry(geometry: GeometryProxy) -> EmptyView {
callback(geometry)
return EmptyView()
}
var body: some View {
GeometryReader { geometry in
VStack{
self.setGeometry(geometry: geometry)
self.content(geometry)
}
}
}
}

Answer 2

You can use a simple extension on View to allow arbitrary code execution when building your views.
extension View {
func execute(_ closure: () -> Void) -> Self {
closure()
return self
}
}
And then
var body: some View {
GeometryReader { proxy
Color.clear.execute {
self.myObject.useProxy(proxy)
}
}
}

Answer 3

Another option is to set the value using .onAppear
struct TranslatorView: View {
#ObservedObject var settings = TranslationViewModel(spacing: 4, charSize: 20)
var body: some View {
GeometryReader { geometry in
VStack{
TextField("Enter your name", text:self.$settings.translateString)
} .onAppear {
settings.ScreenSize = geometry.size.width
}
}
}
}