This is the view I am trying to create:
Everything except the orange line is in place and working (the green ones are just helper lines for visualisation).
I am trying to retrieve informations on rendered views and set view properties to their rect to calculate the orange Path. Right now, this results in the Modifying state during view update, this will cause undefined behavior. error.
What do I need to change in order to make this work?
Here's my view:
struct MyView: View {
#State private var titleRect: CGRect = .zero
#State private var dividerRect: CGRect = .zero
var body: some View {
ZStack {
RoundedRectangle(cornerRadius: 25.0)
.foregroundColor(.yellow)
VStack {
Text("Some fancy title …")
.border(.green) //
.background {
GeometryReader { proxy -> Color in
titleRect = proxy.frame(in: .named("root"))
return .clear
}
}
Rectangle()
.frame(height: 20.0)
.foregroundColor(.clear)
Rectangle()
.frame(height: 1.0)
.background {
GeometryReader { proxy -> Color in
dividerRect = proxy.frame(in: .named("root"))
return .clear
}
}
Spacer()
}
.padding(.top)
Path { path in
path.move(to: CGPoint(x: dividerRect.minX, y: titleRect.maxY)) // startingPoint
path.addLine(to: CGPoint(x: dividerRect.width * 2/3, y: dividerRect.maxY)) // midPoint
path.addLine(to: CGPoint(x: dividerRect.maxX, y: titleRect.maxY)) // endPoint
}
}
.padding()
.coordinateSpace(name: "root")
}
}
I think I found a good workaround for my problem by implementing a ViewModifier that can get me the frame size for arbitrary views I need it for:
struct MeasureSizeModifier: ViewModifier {
let callback: (CGSize) -> ()
func body(content: Content) -> some View {
content
.background {
GeometryReader { proxy in
Color.clear
.onAppear {
callback(proxy.size)
}
}
}
}
}
extension View {
func measureSize(_ callback: #escaping (CGSize) -> () ) -> some View {
modifier(MeasureSizeModifier(callback: callback))
}
}
Credits go out to "Flo Writes Code" on YouTube for his tutorial on this: How to use GeometryReader
BEST in SwiftUl!
After having implemented what is suggested, I can use this extension like so in my specific case:
struct MyView: View {
#State private var containerWidth: CGFloat = .zero
#State private var titleHeight: CGFloat = .zero
var body: some View {
ZStack(alignment: .top) {
RoundedRectangle(cornerRadius: 25.0)
.measureSize { size in
containerWidth = size.width
print(containerWidth)
}
.foregroundColor(.yellow)
Text("Some fancy title …")
.border(.green)
.measureSize { size in
titleHeight = size.height
}
Path { path in
path.move(to: CGPoint(x: .zero, y: titleHeight))
path.addLine(to: CGPoint(x: containerWidth * 0.67, y: titleHeight * 3))
path.addLine(to: CGPoint(x: containerWidth, y: titleHeight))
path.move(to: CGPoint(x: .zero, y: titleHeight * 3))
path.addLine(to: CGPoint(x: containerWidth, y: titleHeight * 3))
}
.stroke(.black)
.border(.green)
HStack {
Text("Y")
Spacer()
Text("N")
}
.padding(.horizontal, 8)
.position(x: containerWidth / 2, y: titleHeight * 2)
.frame(width: containerWidth)
}
.padding()
}
}
I will have other places where I will be glad to have this extension in my toolbelt 🎉
I have a view in SwiftUI. This view has some random images on it in various random positions. Check the code below.
struct ContentView: View {
let screenWidth = UIScreen.main.bounds.width
let screenHeight = UIScreen.main.bounds.height
var body: some View {
ZStack {
ForEach(0..<5) { _ in
Image(systemName: "plus")
.frame(width: 30, height: 30)
.background(Color.green)
.position(
x: CGFloat.random(in: 0..<screenWidth),
y: CGFloat.random(in: 0..<screenHeight)
)
}
}
.ignoreSafeArea()
}
}
I need to get the exact position of these random added images and pass the positions to another transparent view that shows up with a ZStack on top of the previous view. In the transparent popup fullscreen ZStack view i need to point to the position of the images i randomly put in the previous view using arrow images. Is this somehow possible in swiftui? I am new in swiftui so any help or suggestion appreciated.
Store the random offsets in a #State var and generate them in .onAppear { }. Then you can use them to position the random images and pass the offsets to the overlay view:
struct ContentView: View {
#State private var imageOffsets: [CGPoint] = Array(repeating: CGPoint.zero, count: 5)
#State private var showingOverlay = true
let screenWidth = UIScreen.main.bounds.width
let screenHeight = UIScreen.main.bounds.height
var body: some View {
ZStack {
ForEach(0..<5) { index in
Image(systemName: "plus")
.frame(width: 30, height: 30)
.background(Color.green)
.position(
x: imageOffsets[index].x,
y: imageOffsets[index].y
)
}
}
.ignoresSafeArea()
.onAppear {
for index in 0..<5 {
imageOffsets[index] = CGPoint(x: .random(in: 0..<screenWidth), y: .random(in: 0..<screenHeight))
}
}
.overlay {
if showingOverlay {
OverlayView(imageOffsets: imageOffsets)
}
}
}
}
struct OverlayView: View {
let imageOffsets: [CGPoint]
var body: some View {
ZStack {
Color.clear
ForEach(0..<5) { index in
Circle()
.stroke(.blue)
.frame(width: 40, height: 40)
.position(
x: imageOffsets[index].x,
y: imageOffsets[index].y
)
}
}
.ignoresSafeArea()
}
}
I have a TabView with some views that have DragGestures inside. I want to be able to drag the views along with the TabView paging. I am trying to use simultaneousGesture for the drag gesture. This works with a ScrollView but not with a TabView. As you can see in the example the green square on the second page can be dragged around but this doesn't happen simultaneously with the TabViews horizontal scrolling.
Here is a simplified version of the code:
struct ContentView: View {
let colors:[Color] = [.red, .green, .blue]
#State private var location: CGPoint = CGPoint(x: 100, y: 100);
var simpleDrag: some Gesture {
DragGesture()
.onChanged { value in
self.location = value.location
}
.onEnded {_ in }
}
var body: some View {
TabView{
ForEach(colors, id: \.self) { color in
Group {
if color == .green {
VStack {
color
.frame(width:100, height: 100)
.position(location)
.simultaneousGesture(simpleDrag)
}
} else {
color
}
}
.frame(width: 200, height: 200)
}
}
.frame(width: 400, height: 400)
.tabViewStyle(.page(indexDisplayMode: .never))
}
}
And here is a version with a ScrollView that works really well, it even scrolls the scroll view when moving side to side and moves the green box when dragging it up and down.
struct ContentView: View {
let colors:[Color] = [.red, .green, .blue]
#State private var location: CGPoint = CGPoint(x: 100, y: 100);
var simpleDrag: some Gesture {
DragGesture()
.onChanged { value in
self.location = value.location
}
.onEnded {_ in }
}
var body: some View {
ScrollView(.horizontal) {
HStack {
ForEach(colors, id: \.self) { color in
Group {
if color == .green {
VStack {
color
.frame(width:100, height: 100)
.position(location)
.simultaneousGesture(simpleDrag)
}
} else {
color
}
}
.frame(width: 200, height: 200)
}
}
}
.frame(width: 400, height: 400)
}
}
I've been searching for a similar answer as well. The closest I could find to a solution is to set the minimumDistance parameter of DragGesture. I found that DragGesture(minimumDistance:20) works fairly well to allow the TabView paging to happen before the DragGesture kicks in. It does delay the other gesture by 20 pixels, but it seems like a fair compromise to allow for both kind of gestures to function
I have several dozen Texts that I would like to position such that their leading baseline (lastTextBaseline) is at a specific coordinate. position can only set the center. For example:
import SwiftUI
import PlaygroundSupport
struct Location: Identifiable {
let id = UUID()
let point: CGPoint
let angle: Double
let string: String
}
let locations = [
Location(point: CGPoint(x: 54.48386479999999, y: 296.4645408), angle: -0.6605166885682314, string: "Y"),
Location(point: CGPoint(x: 74.99159120000002, y: 281.6336352), angle: -0.589411952788817, string: "o"),
]
struct ContentView: View {
var body: some View {
ZStack {
ForEach(locations) { run in
Text(verbatim: run.string)
.font(.system(size: 48))
.border(Color.green)
.rotationEffect(.radians(run.angle))
.position(run.point)
Circle() // Added to show where `position` is
.frame(maxWidth: 5)
.foregroundColor(.red)
.position(run.point)
}
}
}
}
PlaygroundPage.current.setLiveView(ContentView())
This locates the strings such that their center is at the desired point (marked as a red circle):
I would like to adjust this so that the leading baseline is at this red dot. In this example, a correct layout would move the glyphs up and to the right.
I have tried adding .topLeading alignment to the ZStack, and then using offset rather than position. This will let me align based on the top-leading corner, but that's not the corner I want to layout. For example:
ZStack(alignment: .topLeading) { // add alignment
Rectangle().foregroundColor(.clear) // to force ZStack to full size
ForEach(locations) { run in
Text(verbatim: run.string)
.font(.system(size: 48))
.border(Color.green)
.rotationEffect(.radians(run.angle), anchor: .topLeading) // rotate on top-leading
.offset(x: run.point.x, y: run.point.y)
}
}
I've also tried changing the "top" alignment guide for the Texts:
.alignmentGuide(.top) { d in d[.lastTextBaseline]}
This moves the red dots rather than the text, so I don't believe this is on the right path.
I am considering trying to adjust the locations themselves to take into account the size of the Text (which I can predict using Core Text), but I am hoping to avoid calculating a lot of extra bounding boxes.
So, as far as I can tell, alignment guides can't be used in this way – yet. Hopefully this will be coming soon, but in the meantime we can do a little padding and overlay trickery to get the desired effect.
Caveats
You will need to have some way of retrieving the font metrics – I'm using CTFont to initialise my Font instances and retrieving metrics that way.
As far as I can tell, Playgrounds aren't always representative of how a SwiftUI layout will be laid out on the device, and certain inconsistencies arise. One that I've identified is that the displayScale environment value (and the derived pixelLength value) is not set correctly by default in playgrounds and even previews. Therefore, you have to set this manually in these environments if you want a representative layout (FB7280058).
Overview
We're going to combine a number of SwiftUI features to get the outcome we want here. Specifically, transforms, overlays and the GeometryReader view.
First, we'll align the baseline of our glyph to the baseline of our view. If we have the font's metrics we can use the font's 'descent' to shift our glyph down a little so it sits flush with the baseline – we can use the padding view modifier to help us with this.
Next, we're going to overlay our glyph view with a duplicate view. Why? Because within an overlay we're able to grab the exact metrics of the view underneath. In fact, our overlay will be the only view the user sees, the original view will only be utilised for its metrics.
A couple of simple transforms will position our overlay where we want it, and we'll then hide the view that sits underneath to complete the effect.
Step 1: Set up
First, we're going to need some additional properties to help with our calculations. In a proper project you could organise this into a view modifier or similar, but for conciseness we'll add them to our existing view.
#Environment(\.pixelLength) var pixelLength: CGFloat
#Environment(\.displayScale) var displayScale: CGFloat
We'll also need a our font initialised as a CTFont so we can grab its metrics:
let baseFont: CTFont = {
let desc = CTFontDescriptorCreateWithNameAndSize("SFProDisplay-Medium" as CFString, 0)
return CTFontCreateWithFontDescriptor(desc, 48, nil)
}()
Then some calculations. This calculates some EdgeInsets for a text view that will have the effect of moving the text view's baseline to the bottom edge of the enclosing padding view:
var textPadding: EdgeInsets {
let baselineShift = (displayScale * baseFont.descent).rounded(.down) / displayScale
let baselineOffsetInsets = EdgeInsets(top: baselineShift, leading: 0, bottom: -baselineShift, trailing: 0)
return baselineOffsetInsets
}
We'll also add a couple of helper properties to CTFont:
extension CTFont {
var ascent: CGFloat { CTFontGetAscent(self) }
var descent: CGFloat { CTFontGetDescent(self) }
}
And finally we create a new helper function to generate our Text views that uses the CTFont we defined above:
private func glyphView(for text: String) -> some View {
Text(verbatim: text)
.font(Font(baseFont))
}
Step 2: Adopt our glyphView(_:) in our main body call
This step is simple and has us adopt the glyphView(_:) helper function we define above:
var body: some View {
ZStack {
ForEach(locations) { run in
self.glyphView(for: run.string)
.border(Color.green, width: self.pixelLength)
.position(run.point)
Circle() // Added to show where `position` is
.frame(maxWidth: 5)
.foregroundColor(.red)
.position(run.point)
}
}
}
This gets us here:
Step 3: Baseline shift
Next we shift the baseline of our text view so that it sits flush with the bottom of our enclosing padding view. This is just a case of adding a padding modifier to our new glyphView(_:)function that utilises the padding calculation we define above.
private func glyphView(for text: String) -> some View {
Text(verbatim: text)
.font(Font(baseFont))
.padding(textPadding) // Added padding modifier
}
Notice how the glyphs are now sitting flush with the bottom of their enclosing views.
Step 4: Add an overlay
We need to get the metrics of our glyph so that we are able to accurately place it. However, we can't get those metrics until we've laid out our view. One way around this is to duplicate our view and use one view as a source of metrics that is otherwise hidden, and then present a duplicate view that we position using the metrics we've gathered.
We can do this with the overlay modifier together with a GeometryReader view. And we'll also add a purple border and make our overlay text blue to differentiate it from the previous step.
self.glyphView(for: run.string)
.border(Color.green, width: self.pixelLength)
.overlay(GeometryReader { geometry in
self.glyphView(for: run.string)
.foregroundColor(.blue)
.border(Color.purple, width: self.pixelLength)
})
.position(run.point)
Step 5: Translate
Making use of the metrics we now have available for us to use, we can shift our overlay up and to the right so that the bottom left corner of the glyph view sits on our red positioning spot.
self.glyphView(for: run.string)
.border(Color.green, width: self.pixelLength)
.overlay(GeometryReader { geometry in
self.glyphView(for: run.string)
.foregroundColor(.blue)
.border(Color.purple, width: self.pixelLength)
.transformEffect(.init(translationX: geometry.size.width / 2, y: -geometry.size.height / 2))
})
.position(run.point)
Step 6: Rotate
Now we have our view in position we can finally rotate.
self.glyphView(for: run.string)
.border(Color.green, width: self.pixelLength)
.overlay(GeometryReader { geometry in
self.glyphView(for: run.string)
.foregroundColor(.blue)
.border(Color.purple, width: self.pixelLength)
.transformEffect(.init(translationX: geometry.size.width / 2, y: -geometry.size.height / 2))
.rotationEffect(.radians(run.angle))
})
.position(run.point)
Step 7: Hide our workings out
Last step is to hide our source view and set our overlay glyph to its proper colour:
self.glyphView(for: run.string)
.border(Color.green, width: self.pixelLength)
.hidden()
.overlay(GeometryReader { geometry in
self.glyphView(for: run.string)
.foregroundColor(.black)
.border(Color.purple, width: self.pixelLength)
.transformEffect(.init(translationX: geometry.size.width / 2, y: -geometry.size.height / 2))
.rotationEffect(.radians(run.angle))
})
.position(run.point)
The final code
//: A Cocoa based Playground to present user interface
import SwiftUI
import PlaygroundSupport
struct Location: Identifiable {
let id = UUID()
let point: CGPoint
let angle: Double
let string: String
}
let locations = [
Location(point: CGPoint(x: 54.48386479999999, y: 296.4645408), angle: -0.6605166885682314, string: "Y"),
Location(point: CGPoint(x: 74.99159120000002, y: 281.6336352), angle: -0.589411952788817, string: "o"),
]
struct ContentView: View {
#Environment(\.pixelLength) var pixelLength: CGFloat
#Environment(\.displayScale) var displayScale: CGFloat
let baseFont: CTFont = {
let desc = CTFontDescriptorCreateWithNameAndSize("SFProDisplay-Medium" as CFString, 0)
return CTFontCreateWithFontDescriptor(desc, 48, nil)
}()
var textPadding: EdgeInsets {
let baselineShift = (displayScale * baseFont.descent).rounded(.down) / displayScale
let baselineOffsetInsets = EdgeInsets(top: baselineShift, leading: 0, bottom: -baselineShift, trailing: 0)
return baselineOffsetInsets
}
var body: some View {
ZStack {
ForEach(locations) { run in
self.glyphView(for: run.string)
.border(Color.green, width: self.pixelLength)
.hidden()
.overlay(GeometryReader { geometry in
self.glyphView(for: run.string)
.foregroundColor(.black)
.border(Color.purple, width: self.pixelLength)
.transformEffect(.init(translationX: geometry.size.width / 2, y: -geometry.size.height / 2))
.rotationEffect(.radians(run.angle))
})
.position(run.point)
Circle() // Added to show where `position` is
.frame(maxWidth: 5)
.foregroundColor(.red)
.position(run.point)
}
}
}
private func glyphView(for text: String) -> some View {
Text(verbatim: text)
.font(Font(baseFont))
.padding(textPadding)
}
}
private extension CTFont {
var ascent: CGFloat { CTFontGetAscent(self) }
var descent: CGFloat { CTFontGetDescent(self) }
}
PlaygroundPage.current.setLiveView(
ContentView()
.environment(\.displayScale, NSScreen.main?.backingScaleFactor ?? 1.0)
.frame(width: 640, height: 480)
.background(Color.white)
)
And that's it. It's not perfect, but until SwiftUI gives us an API that allows us to use alignment anchors to anchor our transforms, it might get us by!
this code takes care of the font metrics, and position text as you asked
(If I properly understood your requirements :-))
import SwiftUI
import PlaygroundSupport
struct BaseLine: ViewModifier {
let alignment: HorizontalAlignment
#State private var ref = CGSize.zero
private var align: CGFloat {
switch alignment {
case .leading:
return 1
case .center:
return 0
case .trailing:
return -1
default:
return 0
}
}
func body(content: Content) -> some View {
ZStack {
Circle().frame(width: 0, height: 0, alignment: .center)
content.alignmentGuide(VerticalAlignment.center) { (d) -> CGFloat in
DispatchQueue.main.async {
self.ref.height = d[VerticalAlignment.center] - d[.lastTextBaseline]
self.ref.width = d.width / 2
}
return d[VerticalAlignment.center]
}
.offset(x: align * ref.width, y: ref.height)
}
}
}
struct ContentView: View {
var body: some View {
ZStack {
Cross(size: 20, color: Color.red).position(x: 200, y: 200)
Cross(size: 20, color: Color.red).position(x: 200, y: 250)
Cross(size: 20, color: Color.red).position(x: 200, y: 300)
Cross(size: 20, color: Color.red).position(x: 200, y: 350)
Text("WORLD").font(.title).border(Color.gray).modifier(BaseLine(alignment: .trailing))
.rotationEffect(.degrees(45))
.position(x: 200, y: 200)
Text("Y").font(.system(size: 150)).border(Color.gray).modifier(BaseLine(alignment: .center))
.rotationEffect(.degrees(45))
.position(x: 200, y: 250)
Text("Y").font(.system(size: 150)).border(Color.gray).modifier(BaseLine(alignment: .leading))
.rotationEffect(.degrees(45))
.position(x: 200, y: 350)
Text("WORLD").font(.title).border(Color.gray).modifier(BaseLine(alignment: .leading))
.rotationEffect(.degrees(225))
.position(x: 200, y: 300)
}
}
}
struct Cross: View {
let size: CGFloat
var color = Color.clear
var body: some View {
Path { p in
p.move(to: CGPoint(x: size / 2, y: 0))
p.addLine(to: CGPoint(x: size / 2, y: size))
p.move(to: CGPoint(x: 0, y: size / 2))
p.addLine(to: CGPoint(x: size, y: size / 2))
}
.stroke().foregroundColor(color)
.frame(width: size, height: size, alignment: .center)
}
}
PlaygroundPage.current.setLiveView(ContentView())
Updated: you could try the following variants
let font = UIFont.systemFont(ofSize: 48)
var body: some View {
ZStack {
ForEach(locations) { run in
Text(verbatim: run.string)
.font(Font(self.font))
.border(Color.green)
.offset(x: 0, y: -self.font.lineHeight / 2.0)
.rotationEffect(.radians(run.angle))
.position(run.point)
Circle() // Added to show where `position` is
.frame(maxWidth: 5)
.foregroundColor(.red)
.position(run.point)
}
}
}
there is also next interesting variant, use ascender instead of above lineHeight
.offset(x: 0, y: -self.font.ascender / 2.0)
I'm trying to create a custom percentage bar chart like the one below
however, I'm unable to set the bar width programmatically, what am I doing wrong?
Setting .frame(width: UIScreen.main.bounds.width * percent, height:23) produces the following error : Ambiguous reference to member 'frame(width:height:alignment:)'
import SwiftUI
struct BarChartView : View {
#Binding var percent: Float
init(percentage: Binding<Float>){
self._percent = percentage
}
var body: some View {
ZStack {
Rectangle().fill(Color.yellow).frame(height: 30).border(Color.black, width:1)
HStack {
RoundedRectangle(cornerRadius: 5)
.fill(Color.green).frame(width: 300, height:23).padding(2)
Spacer()
}
HStack {
Text("Bar Chart View").padding (2)
Spacer()
Text("\(String(format: "%02.f", arguments: [self.percent]))%")
}
}
}
}
Is there a way to determine the width of the first rectangle in the ZStack and calc a percentage off of that. I would like this to automatically update in landscape mode too, if possible.
You could use GeometryReader to play with dimensions, but in this case I think using a shape is a much better fit:
import SwiftUI
struct BarChartView : View {
#Binding var percent: Float
init(percentage: Binding<Float>){
self._percent = percentage
}
var body: some View {
HStack {
Text("Bar Chart View").padding (5)
Spacer()
Text("\(String(format: "%02.f", arguments: [self.percent * 100]))%").padding(5)
}
.background(LeftPart(pct: CGFloat(percent)).fill(Color.green))
.background(RightPart(pct: CGFloat(percent)).fill(Color.yellow))
.padding(10)
}
struct LeftPart: Shape {
let pct: CGFloat
func path(in rect: CGRect) -> Path {
var p = Path()
p.addRoundedRect(in: CGRect(x: 0, y: 0, width: rect.size.width * pct, height: rect.size.height), cornerSize: .zero)
return p
}
}
struct RightPart: Shape {
let pct: CGFloat
func path(in rect: CGRect) -> Path {
var p = Path()
p.addRoundedRect(in: CGRect(x: rect.size.width * pct, y: 0, width: rect.size.width * (1-pct), height: rect.size.height), cornerSize: .zero)
return p
}
}
}
struct ContentView: View {
var body: some View {
BarChartView(percentage: .constant(0.75))
}
}