问题描述
我正在尝试实现类似 iOS Timer App 时间选择器控件的功能:
我已经研究过 DatePicker,但它没有秒视图。
解决方法
经过一段时间的调查,结果证明唯一的解决方案是从头开始编写。我把它贴在这里给有同样问题的人:
import SwiftUI
struct MultiComponentPicker<Tag: Hashable>: View {
let columns: [Column]
var selections: [Binding<Tag>]
init?(columns: [Column],selections: [Binding<Tag>]) {
guard !columns.isEmpty && columns.count == selections.count else {
return nil
}
self.columns = columns
self.selections = selections
}
var body: some View {
GeometryReader { geometry in
HStack(spacing: 0) {
ForEach(0 ..< columns.count) { index in
let column = columns[index]
ZStack(alignment: Alignment.init(horizontal: .customCenter,vertical: .center)) {
if (!column.label.isEmpty && !column.options.isEmpty) {
HStack {
Text(verbatim: column.options.last!.text)
.foregroundColor(.clear)
.alignmentGuide(.customCenter) { $0[HorizontalAlignment.center] }
Text(column.label)
}
}
Picker(column.label,selection: selections[index]) {
ForEach(column.options,id: \.tag) { option in
Text(verbatim: option.text).tag(option.tag)
}
}
.pickerStyle(WheelPickerStyle())
.frame(width: geometry.size.width / CGFloat(columns.count),height: geometry.size.height)
.clipped()
}
}
}
}
}
}
extension MultiComponentPicker {
struct Column {
struct Option {
var text: String
var tag: Tag
}
var label: String
var options: [Option]
}
}
private extension HorizontalAlignment {
enum CustomCenter: AlignmentID {
static func defaultValue(in context: ViewDimensions) -> CGFloat { context[HorizontalAlignment.center] }
}
static let customCenter = Self(CustomCenter.self)
}
// MARK: - Demo preview
struct MultiComponentPicker_Previews: PreviewProvider {
static var columns = [
MultiComponentPicker.Column(label: "h",options: Array(0...23).map { MultiComponentPicker.Column.Option(text: "\($0)",tag: $0) }),MultiComponentPicker.Column(label: "min",options: Array(0...59).map { MultiComponentPicker.Column.Option(text: "\($0)",MultiComponentPicker.Column(label: "sec",]
static var selection1: Int = 23
static var selection2: Int = 59
static var selection3: Int = 59
static var previews: some View {
MultiComponentPicker(columns: columns,selections: [.constant(selection1),.constant(selection2),.constant(selection3)]).frame(height: 300).previewLayout(.sizeThatFits)
}
}
这是它的样子:
我已经把它变得非常通用,所以你可以将它用于任何类型的多组件选择器,而不仅仅是时间选择器。
解决方案的基础归功于 Matteo Pacini。