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[英]SwiftUI animation problem with a binding to a StateObject inside a NavigationView
[英]SwiftUI animation not occurring on update of Binding
我正在尝试创建一个在绑定值非零时出现的“弹出视图”。
我有一个PopupCard
class 它是通用的Content
和一些Value
......
struct PopupCard<Content: View, Value>: View {
@Binding private var data: Value?
private let content: (Value) -> Content
init(data: Binding<Value?>, @ViewBuilder content: @escaping (Value) -> Content) {
self._data = data
self.content = content
}
var body: some View {
Group {
if data != nil {
HStack {
self.content(self.data!)
.padding()
Spacer()
}
.frame(width: UIScreen.main.bounds.width - 40)
.background(
Rectangle()
.fill(Color.yellow)
.shadow(color: Color.black.opacity(0.2), radius: 5, y: 0)
)
.offset(y: self.data == nil ? -100 : 0)
.animation(.default)
}
}
}
}
我还在View
上创建了以下扩展...
extension View {
func popup<Content: View, Value>(data: Binding<Value?>, @ViewBuilder content: @escaping (Value) -> Content) -> some View {
return ZStack {
self
VStack {
Spacer()
PopupCard(data: data, content: content)
}
}
}
}
除了 animation 之外,这一切都很好。 该卡按预期出现和消失,但没有 animation。 这在以下预览中得到了演示……
struct PopupCard_Previews: PreviewProvider {
struct PreviewView: View {
@State var name: String? = "Hello"
var body: some View {
TabView {
Button("Toggle", action: {
self.name = self.name == nil ? "Hello" : nil
})
.popup(data: $name) { string in
Text(string)
}
}
}
}
static var previews: some View {
PreviewView()
}
}
我如何让这个动画进/出?
这是固定的变体(如果我正确理解了意图)。 使用 Xcode 11.4 / iOS 13.4 测试
struct PopupCard<Content: View, Value>: View {
@Binding private var data: Value?
private let content: (Value) -> Content
init(data: Binding<Value?>, @ViewBuilder content: @escaping (Value) -> Content) {
self._data = data
self.content = content
}
var body: some View {
Group {
HStack {
if data != nil {
self.content(self.data!).padding()
} else {
Text("")
}
Spacer()
}
.frame(width: UIScreen.main.bounds.width - 40)
.background(
Rectangle()
.fill(Color.yellow)
.shadow(color: Color.black.opacity(0.2), radius: 5, y: 0)
)
.compositingGroup()
.offset(y: self.data == nil ? 100 : 0)
.animation(.default)
}
}
}
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