SwiftUI学习之state和Binding的区别浅析

@state 绑定值的状态,其属性的修饰官方推荐使用private.上代码(ps:这里没用private 进行修饰,是为了演示区别)
import SwiftUI

				?

									struct FilterView: View {

									// @Binding var isFavorite: Bool

									 @State var isFavorite = true

									 var body: some View {

									  Toggle(isOn: $isFavorite) {

									  }

									  let buttonTitle = isFavorite ? "呕吼" : "顿顿"

									  Text(buttonTitle)

									 }

									}

									struct ProductView: View {

									 var titleS: String

									 //:不想让外部访问的变量 需要初始化

									 @State private var changeButtonTtile = true

									 var body: some View {

									  Button (action: {

									   changeButtonTtile.toggle()

									  }) {

									   let buttonTitle = changeButtonTtile ? "哈哈哈" : "啦啦啦啦"

									   Text(buttonTitle)

									   FilterView(isFavorite: changeButtonTtile)

									  }

									 }

									}

这里我们看到 @State var isFavorite = true通过state 进行修饰.这个时候我们点击FilterView的开关我们只能刷新当前FilterView的界面.注意这里:FilterView(isFavorite: changeButtonTtile) 初始化传入的是changeButtonTtile的value,也就实际值.

下面我们把State注释掉 ,打开@Bingding 那一行

				?

									import SwiftUI

									struct FilterView: View {

									 @Binding var isFavorite: Bool

									// @State var isFavorite = true

									 var body: some View {

									  Toggle(isOn: $isFavorite) {

									  }

									  let buttonTitle = isFavorite ? "呕吼" : "顿顿"

									  Text(buttonTitle)

									 }

									}

									struct ProductView: View {

									 var titleS: String

									 //:不想让外部访问的变量 需要初始化

									 @State private var changeButtonTtile = true

									 var body: some View {

									  Button (action: {

									   changeButtonTtile.toggle()

									  }) {

									   let buttonTitle = changeButtonTtile ? "哈哈哈" : "啦啦啦啦"

									   Text(buttonTitle)

									   FilterView(isFavorite: $changeButtonTtile)

									//:注意这里的取值 变成了$

									  }

									 }

									}