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Working with UI Controls
Willie edited this page Jun 9, 2019
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在
Landmarksapp 中,用户可以创建个人资料来展示个性。为了让用户能修改个人资料,我们需要添加一个编辑模式,并设计一个偏好设置界面。我们将使用多种常用的 UI 控件来处理数据,并在用户保存修改时更新
Landmarksmodel。
- 预计完成时间:25 分钟
- 项目文件:下载
Landmarks app 在本地保存一些详细配置和偏好设置。在用户编辑他们的详情前,会在一个没有修改控件的摘要 view 中显示出来。
1.1 在 Landmark 文件夹里创建一个新文件夹 Profile ,然后在里面创建一个新文件 ProfileHost.swift 。
ProfileHost view 负责用户信息的静态摘要 view 以及编辑模式。
ProfileHost.swift
import SwiftUI
struct ProfileHost: View {
@State var profile = Profile.default
var body: some View {
Text("Profile for: \(profile.username)")
}
}
#if DEBUG
struct ProfileHost_Previews: PreviewProvider {
static var previews: some View {
ProfileHost()
}
}
#endif
1.2 在 Home.swift 中,把静态的 Text 换成上一步中创建的 ProfileHost 。
现在 home screen 中的 profile 按钮会显示一个带有用户信息的模态。
Home.swift
import SwiftUI
struct CategoryHome: View {
var categories: [String: [Landmark]] {
.init(
grouping: landmarkData,
by: { 0ドル.category.rawValue }
)
}
var featured: [Landmark] {
landmarkData.filter { 0ドル.isFeatured }
}
var body: some View {
NavigationView {
List {
FeaturedLandmarks(landmarks: featured)
.scaledToFill()
.frame(height: 200)
.clipped()
.listRowInsets(EdgeInsets())
ForEach(categories.keys.sorted().identified(by: \.self)) { key in
CategoryRow(categoryName: key, items: self.categories[key]!)
}
.listRowInsets(EdgeInsets())
NavigationButton(destination: LandmarkList()) {
Text("See All")
}
}
.navigationBarTitle(Text("Featured"))
.navigationBarItems(trailing:
PresentationButton(
Image(systemName: "person.crop.circle")
.imageScale(.large)
.accessibility(label: Text("User Profile"))
.padding(),
destination: ProfileHost()
)
)
}
}
}
struct FeaturedLandmarks: View {
var landmarks: [Landmark]
var body: some View {
landmarks[0].image(forSize: 250).resizable()
}
}
#if DEBUG
struct CategoryHome_Previews: PreviewProvider {
static var previews: some View {
CategoryHome()
}
}
#endif
1.3 创建一个新 view ProfileSummary ,它持有一个 Profile 实例并显示一些基本用户信息。
ProfileSummary 持有一个 Profile 值要比一个 profile 的 binding 更合适,因为它的父 view ProfileHost 负责管理它的 state 。
ProfileSummary.swift
import SwiftUI
struct ProfileSummary: View {
var profile: Profile
static let goalFormat: DateFormatter = {
let formatter = DateFormatter()
formatter.dateFormat = "MMMM d, yyyy"
return formatter
}()
var body: some View {
List {
Text(profile.username)
.bold()
.font(.title)
Text("Notifications: \(self.profile.prefersNotifications ? "On": "Off" )")
Text("Seasonal Photos: \(self.profile.seasonalPhoto.rawValue)")
Text("Goal Date: \(self.profile.goalDate, formatter: Self.goalFormat)")
}
}
}
#if DEBUG
struct ProfileSummary_Previews: PreviewProvider {
static var previews: some View {
ProfileSummary(profile: Profile.default)
}
}
#endif
1.4 更新 ProfileHost 来显示摘要 view 。
ProfileHost.swift
import SwiftUI
struct ProfileHost: View {
@State var profile = Profile.default
var body: some View {
VStack(alignment: .leading, spacing: 20) {
ProfileSummary(profile: self.profile)
}
.padding()
}
}
#if DEBUG
struct ProfileHost_Previews: PreviewProvider {
static var previews: some View {
ProfileHost()
}
}
#endif
1.5 创建一个新 view HikeBadge ,这个 view 组合了 绘制路径和形状 中的徽章以及一些远足的描述文本。
徽章只是一个图形,因此 HikeBadge 中的文本以及 accessibility(label:) 方法让徽章对其他用户来说含义更加清晰。
两个调用 frame(width:height:) 的方法让徽章以 ×ばつ300 点的设计尺寸进行缩放渲染。
HikeBadge.swift
import SwiftUI
struct HikeBadge: View {
var name: String
var body: some View {
VStack(alignment: .center) {
Badge()
.frame(width: 300, height: 300)
.scaleEffect(1.0 / 3.0)
.frame(width: 100, height: 100)
Text(name)
.font(.caption)
.accessibility(label: Text("Badge for \(name)."))
}
}
}
#if DEBUG
struct HikeBadge_Previews : PreviewProvider {
static var previews: some View {
HikeBadge(name: "Preview Testing")
}
}
#endif
1.6 更新 ProfileSummary ,给它添加几个具有不同色调的徽章以及获得徽章的原因。
ProfileSummary.swift
import SwiftUI
struct ProfileSummary: View {
var profile: Profile
static let goalFormat: DateFormatter = {
let formatter = DateFormatter()
formatter.dateFormat = "MMMM d, yyyy"
return formatter
}()
var body: some View {
List {
Text(profile.username)
.bold()
.font(.title)
Text("Notifications: \(self.profile.prefersNotifications ? "On": "Off" )")
Text("Seasonal Photos: \(self.profile.seasonalPhoto.rawValue)")
Text("Goal Date: \(self.profile.goalDate, formatter: Self.goalFormat)")
VStack(alignment: .leading) {
Text("Completed Badges")
.font(.headline)
ScrollView {
HStack {
HikeBadge(name: "First Hike")
HikeBadge(name: "Earth Day")
.hueRotation(Angle(degrees: 90))
HikeBadge(name: "Tenth Hike")
.grayscale(0.5)
.hueRotation(Angle(degrees: 45))
}
}
.frame(height: 140)
}
}
}
}
#if DEBUG
struct ProfileSummary_Previews: PreviewProvider {
static var previews: some View {
ProfileSummary(profile: Profile.default)
}
}
#endif
1.7 引入 动画视图与转场 中的 HikeView 来完成 ProfileSummary 。
ProfileSummary.swift
import SwiftUI
struct ProfileSummary: View {
var profile: Profile
static var goalFormat: DateFormatter {
let formatter = DateFormatter()
formatter.dateFormat = "MMMM d, yyyy"
return formatter
}
var body: some View {
List {
Text(profile.username)
.bold()
.font(.title)
Text("Notifications: \(self.profile.prefersNotifications ? "On": "Off" )")
Text("Seasonal Photos: \(self.profile.seasonalPhoto.rawValue)")
Text("Goal Date: \(self.profile.goalDate, formatter: Self.goalFormat)")
VStack(alignment: .leading) {
Text("Completed Badges")
.font(.headline)
ScrollView {
HStack {
HikeBadge(name: "First Hike")
HikeBadge(name: "Earth Day")
.hueRotation(Angle(degrees: 90))
HikeBadge(name: "Tenth Hike")
.grayscale(0.5)
.hueRotation(Angle(degrees: 45))
}
}
.frame(height: 140)
}
VStack(alignment: .leading) {
Text("Recent Hikes")
.font(.headline)
HikeView(hike: hikeData[0])
}
}
}
}
#if DEBUG
struct ProfileSummary_Previews: PreviewProvider {
static var previews: some View {
ProfileSummary(profile: Profile.default)
}
}
#endif
用户需要在个人详情中切换浏览和编辑模式。我们会通过在现有的 ProfileHost 中添加一个 EditButton 来实现编辑模式,并且创建一个带有编辑单个数据控件的 view 。
2.1 创建一个 Environment view 属性,并输入 \.editMode 。
我们可以使用此属性来读取和写入当前编辑范围。
ProfileHost.swift
import SwiftUI
struct ProfileHost: View {
@Environment(\.editMode) var mode
@State var profile = Profile.default
var body: some View {
VStack(alignment: .leading, spacing: 20) {
ProfileSummary(profile: profile)
}
.padding()
}
}
#if DEBUG
struct ProfileHost_Previews: PreviewProvider {
static var previews: some View {
ProfileHost()
}
}
#endif
2.2 创建一个可以切换环境中编辑模式开关的 Edit 按钮。
ProfileHost.swift
import SwiftUI
struct ProfileHost: View {
@Environment(\.editMode) var mode
@State var profile = Profile.default
var body: some View {
VStack(alignment: .leading, spacing: 20) {
HStack {
Spacer()
EditButton()
}
ProfileSummary(profile: profile)
}
.padding()
}
}
#if DEBUG
struct ProfileHost_Previews: PreviewProvider {
static var previews: some View {
ProfileHost()
}
}
#endif
2.3 添加一个用户信息的草稿副本来传递给编辑控件。
为了避免在任何编辑确认之前更新 app 的全局状态,例如在用户输入其名称时,编辑 view 只会对其自身的副本进行操作。
ProfileHost.swift
import SwiftUI
struct ProfileHost: View {
@Environment(\.editMode) var mode
@State var profile = Profile.default
@State var draftProfile = Profile.default
var body: some View {
VStack(alignment: .leading, spacing: 20) {
HStack {
Spacer()
EditButton()
}
ProfileSummary(profile: self.profile)
}
.padding()
}
}
#if DEBUG
struct ProfileHost_Previews: PreviewProvider {
static var previews: some View {
ProfileHost()
}
}
#endif
2.4 添加条件 view,显示静态信息或编辑模式的 view。
目前,编辑模式只是一个静态文本。
ProfileHost.swift
import SwiftUI
struct ProfileHost: View {
@Environment(\.editMode) var mode
@State var profile = Profile.default
@State var draftProfile = Profile.default
var body: some View {
VStack(alignment: .leading, spacing: 20) {
HStack {
Spacer()
EditButton()
}
if self.mode?.value == .inactive {
ProfileSummary(profile: profile)
} else {
Text("Profile Editor")
}
}
.padding()
}
}
#if DEBUG
struct ProfileHost_Previews: PreviewProvider {
static var previews: some View {
ProfileHost()
}
}
#endif
用户信息编辑器主要包含了更改详情时的不同控件。信息中徽章之类某些项目是用户编辑不了的,因此它们不会出现在编辑器中。
为了与信息摘要保持一致,我们会在编辑器中以相同的顺序添加信息详情。
3.1 创建一个新 view ProfileEditor ,然后给用户信息的草稿副本引入一个 binding 。
view 中第一个控件是一个 TextField ,它控制并更新一个字符串的 binding,在这里例子中则是用户选择的显示名称。
ProfileEditor.swift
import SwiftUI
struct ProfileEditor: View {
@Binding var profile: Profile
var body: some View {
List {
HStack {
Text("Username").bold()
Divider()
TextField($profile.username)
}
}
}
}
#if DEBUG
struct ProfileEditor_Previews: PreviewProvider {
static var previews: some View {
ProfileEditor(profile: .constant(.default))
}
}
#endif
3.2 更新 ProfileHost 中的条件内容,引入 ProfileEditor 并给它传递一个信息的 binding 。
现在当你点击 Edit 后,信息编辑 view 就会显示。
ProfileHost.swift
import SwiftUI
struct ProfileHost: View {
@Environment(\.editMode) var mode
@State var profile = Profile.default
@State var draftProfile = Profile.default
var body: some View {
VStack(alignment: .leading, spacing: 20) {
HStack {
Spacer()
EditButton()
}
if self.mode?.value == .inactive {
ProfileSummary(profile: profile)
} else {
ProfileEditor(profile: $draftProfile)
}
}
.padding()
}
}
#if DEBUG
struct ProfileHost_Previews: PreviewProvider {
static var previews: some View {
ProfileHost()
}
}
#endif
3.3 添加接收地标相关事件通知的 toggle ,它与用户偏好相对应。
Toggle 是只有 on 或 off 的控件,所以它很适合像 yes 或 no 之类的 Boolean 值。
ProfileEditor.swift
import SwiftUI
struct ProfileEditor: View {
@Binding var profile: Profile
var body: some View {
List {
HStack {
Text("Username").bold()
Divider()
TextField($profile.username)
}
Toggle(isOn: $profile.prefersNotifications) {
Text("Enable Notifications")
}
}
}
}
#if DEBUG
struct ProfileEditor_Previews: PreviewProvider {
static var previews: some View {
ProfileEditor(profile: .constant(.default))
}
}
#endif
3.4 将一个 SegmentedControl 和它的 label 放在一个 VStack 中,使地标照片具有可选择的季节。
ProfileEditor.swift
import SwiftUI
struct ProfileEditor: View {
@Binding var profile: Profile
var body: some View {
List {
HStack {
Text("Username").bold()
Divider()
TextField($profile.username)
}
Toggle(isOn: $profile.prefersNotifications) {
Text("Enable Notifications")
}
VStack(alignment: .leading, spacing: 20) {
Text("Seasonal Photo").bold()
SegmentedControl(selection: $profile.seasonalPhoto) {
ForEach(Profile.Season.allCases.identified(by: \.self)) { season in
Text(season.rawValue).tag(season)
}
}
}
.padding(.top)
}
}
}
#if DEBUG
struct ProfileEditor_Previews: PreviewProvider {
static var previews: some View {
ProfileEditor(profile: .constant(.default))
}
}
#endif
3.5 最后,在季节选择器的下面添加一个 DatePicker ,用来修改到达地标的日期。
ProfileEditor.swift
import SwiftUI
struct ProfileEditor: View {
@Binding var profile: Profile
var body: some View {
List {
HStack {
Text("Username").bold()
Divider()
TextField($profile.username)
}
Toggle(isOn: $profile.prefersNotifications) {
Text("Enable Notifications")
}
VStack(alignment: .leading, spacing: 20) {
Text("Seasonal Photo").bold()
SegmentedControl(selection: $profile.seasonalPhoto) {
ForEach(Profile.Season.allCases.identified(by: \.self)) { season in
Text(season.rawValue).tag(season)
}
}
}
.padding(.top)
VStack(alignment: .leading, spacing: 20) {
Text("Goal Date").bold()
DatePicker(
$profile.goalDate,
minimumDate: Calendar.current.date(byAdding: .year, value: -1, to: profile.goalDate),
maximumDate: Calendar.current.date(byAdding: .year, value: 1, to: profile.goalDate),
displayedComponents: .date
)
}
.padding(.top)
}
}
}
要使编辑在用户退出编辑模式之后才生效,我们需要在编辑期间使用信息的草稿副本,然后仅在用户确认编辑时将草稿副本分配给真实副本。
4.1 给 ProfileHost 添加一个确认按钮。
与 EditButton 提供的 Cancel 按钮不同, Done 按钮会在其操作闭包中将编辑应用于实际的数据。
ProfileHost.swift
import SwiftUI
struct ProfileHost: View {
@Environment(\.editMode) var mode
@State var profile = Profile.default
@State var draftProfile = Profile.default
var body: some View {
VStack(alignment: .leading, spacing: 20) {
HStack {
if self.mode?.value == .active {
Button(action: {
self.profile = self.draftProfile
self.mode?.animation().value = .inactive
}) {
Text("Done")
}
}
Spacer()
EditButton()
}
if self.mode?.value == .inactive {
ProfileSummary(profile: profile)
} else {
ProfileEditor(profile: $draftProfile)
}
}
.padding()
}
}
#if DEBUG
struct ProfileHost_Previews: PreviewProvider {
static var previews: some View {
ProfileHost()
}
}
#endif
4.2 使用 onDisappear(perform:) 方法来清空用户点击 Cancel 按钮时选择丢弃的值。
否则,下次编辑模式激活时会显示旧值。
ProfileHost.swift
import SwiftUI
struct ProfileHost: View {
@Environment(\.editMode) var mode
@State var profile = Profile.default
@State var draftProfile = Profile.default
var body: some View {
VStack(alignment: .leading, spacing: 20) {
HStack {
if self.mode?.value == .active {
Button(action: {
self.profile = self.draftProfile
self.mode?.animation().value = .inactive
}) {
Text("Done")
}
}
Spacer()
EditButton()
}
if self.mode?.value == .inactive {
ProfileSummary(profile: profile)
} else {
ProfileEditor(profile: $draftProfile)
.onDisappear {
self.draftProfile = self.profile
}
}
}
.padding()
}
}
#if DEBUG
struct ProfileHost_Previews: PreviewProvider {
static var previews: some View {
ProfileHost()
}
}
#endif