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//
// BottomSheetView.swift
//
// Created by Majid Jabrayilov
// Copyright © 2019 Majid Jabrayilov. All rights reserved.
//
import SwiftUI
fileprivate enum Constants {
static let radius: CGFloat = 16
static let indicatorHeight: CGFloat = 6
static let indicatorWidth: CGFloat = 60
static let snapRatio: CGFloat = 0.25
static let minHeightRatio: CGFloat = 0.3
}
struct BottomSheetView<Content: View>: View {
@Binding var isOpen: Bool
let maxHeight: CGFloat
let minHeight: CGFloat
let content: Content
let cardPopAnimationResponse: Double = 0.5
@GestureState private var translation: CGFloat = 0
@State var draggedToOpenOffset: CGFloat = 0
@State var draggedToCloseOffset: CGFloat = 0
private var offset: CGFloat {
if isOpen {
return 0 + draggedToCloseOffset
} else {
return maxHeight - minHeight + draggedToOpenOffset // draggedToOpenOffset is always negative
}
}
private var indicator: some View {
RoundedRectangle(cornerRadius: Constants.radius)
.fill(Color.secondary)
.frame(
width: Constants.indicatorWidth,
height: Constants.indicatorHeight
).onTapGesture {
self.draggedToOpenOffset = 0
self.draggedToCloseOffset = 0
withAnimation(.interactiveSpring(response: self.cardPopAnimationResponse)) {
self.isOpen.toggle()
}
}
}
init(isOpen: Binding<Bool>, maxHeight: CGFloat, @ViewBuilder content: () -> Content) {
self.minHeight = maxHeight * Constants.minHeightRatio
self.maxHeight = maxHeight
self.content = content()
self._isOpen = isOpen
}
var body: some View {
GeometryReader { geometry in
VStack(spacing: 0) {
self.indicator.padding()
self.content
}
.frame(width: geometry.size.width, height: self.maxHeight, alignment: .top)
.background(Color(.secondarySystemBackground))
.cornerRadius(Constants.radius)
.frame(height: geometry.size.height, alignment: .bottom)
.offset(y: max(self.offset, 0))
.gesture(
DragGesture().updating(self.$translation) { value, state, _ in
state = value.translation.height
}.onEnded { value in
let snapDistance = self.maxHeight * Constants.snapRatio
// if it's negative, it's dragging up, isOpen = true, open it
// if it's positive, it's moving down, isOpen = false, close it
let yDraggedValue = value.translation.height
let isDraggedUp = yDraggedValue < 0
// dragged value isn't more than snapDistance, go back to where it was
guard abs(value.translation.height) > snapDistance else {
if isDraggedUp {
self.draggedToCloseOffset = 0
self.draggedToOpenOffset = 0
self.draggedToOpenOffset = yDraggedValue
} else {
self.draggedToOpenOffset = 0
self.draggedToCloseOffset = 0
self.draggedToCloseOffset = yDraggedValue
}
withAnimation(.interactiveSpring(response: self.cardPopAnimationResponse)) {
self.draggedToOpenOffset = 0
self.draggedToCloseOffset = 0
self.isOpen = !isDraggedUp
}
return
}
if isDraggedUp {
self.draggedToCloseOffset = 0
self.draggedToOpenOffset = 0
self.draggedToOpenOffset = yDraggedValue
} else {
self.draggedToOpenOffset = 0
self.draggedToCloseOffset = 0
self.draggedToCloseOffset = yDraggedValue
}
withAnimation(.interactiveSpring(response: self.cardPopAnimationResponse)) {
self.isOpen = isDraggedUp
}
}
)
}
}
}
struct BottomSheetView_Previews: PreviewProvider {
static var previews: some View {
BottomSheetView(isOpen: .constant(false), maxHeight: 600) {
Rectangle().fill(Color.red)
}.edgesIgnoringSafeArea(.all)
}
}
@contracorner

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@contracorner contracorner commented Jan 19, 2021

This does not seem to track the drag gesture, which the original gist does. The sheet does not animate to each place.

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