SwiftUI 学习 - 关于@Environment

可是使用@Environment修饰词读写环境变量，系统预设的环境变量或自定义的环境变量。

//自定义变量放入环境变量中
private struct MyEnvironmentKey: EnvironmentKey {
    static let defaultValue: String = "Default value"
}

extension EnvironmentValues {
    var myCustomValue: String {
        get { self[MyEnvironmentKey.self] }
        set { self[MyEnvironmentKey.self] = newValue }
    }
}

//写
MyView().environment(\.myCustomValue, "test")
//读
@Environment(\.myCustomValue) var myCustomValue: String