SwiftUI学习<三>

1、Toggle控件：

 // Switch
 Toggle(isOn: .constant(showFavoriteOnly), label: {
    Text("只显示收藏")
})

2、按钮动画：

struct HikeView: View {
    @State private var showDetail = false
    
    var body: some View {
        Button(action: {
            self.showDetail.toggle()
        }) {
            Image(systemName: "chevron.right.circle")
                .imageScale(.large)
                .rotationEffect(.degrees(showDetail ? 90 : 0))
//            scaleEffect(showDetail ? 1.5 : 1)
                .padding()
                .animation(.spring())
        }
    }
}

3、设置图片：

struct Home: View {
    var body: some View {
        NavigationView {
            List {
                Image(landmarks[0].imageName)
                    .resizable()
                    .scaledToFill()
                    .frame(height: 200)
                    .clipped() // 注意设置的顺序问题
                    .listRowInsets(EdgeInsets()) // 消除间距
            }
        }
    }
}

4、NavigationBarItem：

.navigationTitle("精选")
.navigationBarItems(trailing: Image(systemName: "person.crop.circle")
.imageScale(.large)
.padding())

5、SwiftUI单例的使用：

import Foundation

struct User {
    var username: String
    var preferNotification = true
    var prefersSeason = Season.winter
    var birthday = Date()
    
    // 单例
    static let `default` = Self(username: "思思")
    
    enum Season: String, CaseIterable {
        case spring = "chun"
        case summer = "xia"
        case autumn = "qiu"
        case winter = "dong"
    }
}

6、日期格式的转换：

var dateFormatter: DateFormatter {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "yyyy年M月d日"
    return dateFormatter
}

Text("生日: \(dateFormatter.string(from: profile.birthday))")
Text("生日: \(profile.birthday, formatter: dateFormatter)")

7、SwiftUI转UIViewController：

var page = UIHostingController(rootView: Image(landmarks[0].imageName))