[英]How to add a generic SwiftUI view to another view?
当尝试使用泛型类型初始化/添加视图到另一个 SwiftUI 视图时,我收到错误Type 'T' has no member 'init'
。 如何解决?
我想问题是, View
只是一个协议,它只需要一个body
属性,仅此而已。 但是可以改用什么类型呢?
简单示例:
尝试使用应该创建/显示T
类型的三个视图的TrippleView<T: View>
。 添加视图( RedRectView
或BlueCircleView
)没问题。 将这些视图作为通用参数传递失败:
struct SomeView: View {
var body: some View {
TrippleView<RedRectView>()
TrippleView<BlueCircleView>()
}
}
struct TrippleView<T: View>: View {
var body: some View {
VStack {
// Does NOT work: Type 'T' has no member 'init'
T()
T()
T()
// Works fine
// RedRectView()
// BlueCircleView()
// RedRectView()
}
}
}
struct RedRectView: View {...}
struct BlueCircleView: View {...}
编辑:
TrippleView
当然只是一个例子。 我想像使用任何其他泛型类型一样使用泛型视图:在不同场景中使用通用的基本“类型”。
例如,两个版本的列表视图使用通用CellView
在两个不同的 styles / 布局中显示相同的数据。
您需要在结构中使用 ViewBuilder 来初始化视图。 这是一个例子,
struct TripleView<T: View>: View {
// simple example that takes in one parameter.
var someView: T
init(@ViewBuilder someView: () -> T) {
self.someView = someView()
}
var body: some View {
// You can modify your viewes here.
someView
.foregroundColor(.red)
someView
.foregroundColor(.blue)
someView
.foregroundColor(.green)
}
}
或者你可以接受多个参数
struct TripleViewsWithParam<T1: View, T2: View, T3: View>: View {
// you can take as many parameters as you want.
var someView1: T1
var someView2: T2
var someView3: T3
init(@ViewBuilder someView1: () -> T1, @ViewBuilder someView2: () -> T2, @ViewBuilder someView3: () -> T3) {
self.someView1 = someView1()
self.someView2 = someView2()
self.someView3 = someView3()
}
var body: some View {
VStack {
someView1
someView2
someView3
}
}
}
struct SomeView: View {
var body: some View {
VStack{
TripleView {
Text("Triple View Example")
}
TripleViewsWithParam(
someView1: {
Text("View 1")
}, someView2: {
Text("View 2")
}, someView3: {
Text("View 3")
}
)
}
}
}
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