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@andreyz
Forked from mecid/Calendar.swift
Created November 3, 2020 14:38
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SwiftUI Calendar view using LazyVGrid
import SwiftUI
fileprivate extension DateFormatter {
static var month: DateFormatter {
let formatter = DateFormatter()
formatter.dateFormat = "MMMM"
return formatter
}
static var monthAndYear: DateFormatter {
let formatter = DateFormatter()
formatter.dateFormat = "MMMM yyyy"
return formatter
}
}
fileprivate extension Calendar {
func generateDates(
inside interval: DateInterval,
matching components: DateComponents
) -> [Date] {
var dates: [Date] = []
dates.append(interval.start)
enumerateDates(
startingAfter: interval.start,
matching: components,
matchingPolicy: .nextTime
) { date, _, stop in
if let date = date {
if date < interval.end {
dates.append(date)
} else {
stop = true
}
}
}
return dates
}
}
struct CalendarView<DateView>: View where DateView: View {
@Environment(\.calendar) var calendar
let interval: DateInterval
let showHeaders: Bool
let content: (Date) -> DateView
init(
interval: DateInterval,
showHeaders: Bool = true,
@ViewBuilder content: @escaping (Date) -> DateView
) {
self.interval = interval
self.showHeaders = showHeaders
self.content = content
}
var body: some View {
LazyVGrid(columns: Array(repeating: GridItem(), count: 7)) {
ForEach(months, id: \.self) { month in
Section(header: header(for: month)) {
ForEach(days(for: month), id: \.self) { date in
if calendar.isDate(date, equalTo: month, toGranularity: .month) {
content(date).id(date)
} else {
content(date).hidden()
}
}
}
}
}
}
private var months: [Date] {
calendar.generateDates(
inside: interval,
matching: DateComponents(day: 1, hour: 0, minute: 0, second: 0)
)
}
private func header(for month: Date) -> some View {
let component = calendar.component(.month, from: month)
let formatter = component == 1 ? DateFormatter.monthAndYear : .month
return Group {
if showHeaders {
Text(formatter.string(from: month))
.font(.title)
.padding()
}
}
}
private func days(for month: Date) -> [Date] {
guard
let monthInterval = calendar.dateInterval(of: .month, for: month),
let monthFirstWeek = calendar.dateInterval(of: .weekOfMonth, for: monthInterval.start),
let monthLastWeek = calendar.dateInterval(of: .weekOfMonth, for: monthInterval.end)
else { return [] }
return calendar.generateDates(
inside: DateInterval(start: monthFirstWeek.start, end: monthLastWeek.end),
matching: DateComponents(hour: 0, minute: 0, second: 0)
)
}
}
struct CalendarView_Previews: PreviewProvider {
static var previews: some View {
CalendarView(interval: .init()) { _ in
Text("30")
.padding(8)
.background(Color.blue)
.cornerRadius(8)
}
}
}
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