[英]SwiftUI map @Published var from one ObservableObject to another
I would like two separate ObjservableObject
to share a single @Published var.我想要两个单独的
ObjservableObject
共享一个 @Published var。 Ideally something like the below.理想情况下,如下所示。 That does not compile due to
Cannot assign to property: '$bar' is immutable
.由于
Cannot assign to property: '$bar' is immutable
而无法编译Cannot assign to property: '$bar' is immutable
。 I would like foo and bar to be in sync if a change is made to one or the other.如果对其中一个进行更改,我希望 foo 和 bar 保持同步。
class FooState: ObservableObject {
@Published var foo: Bool = false
}
class BarState: ObservableObject {
@Published var bar: Bool
init(fooState: FooState) {
self.$bar = fooState.$foo // compile error
}
}
let fooState = FooState()
let barState = BarState(fooState: fooState)
print(fooState.foo) // false
print(barState.bar) // false
fooState.foo = true
print(fooState.foo) // true
print(barState.bar) // true
This is not currently supported (I think).目前不支持(我认为)。 The only way I know to work around it is subscribing to the nested observable object yourself and propagating the
objectWillChange
event:我知道解决它的唯一方法是自己订阅嵌套的可观察对象并传播
objectWillChange
事件:
class FooState: ObservableObject {
@Published var foo: Bool = false
}
class BarState: ObservableObject {
var fooState: FooState
var bar: Bool {
return self.fooState.foo
}
private var cancellables = Set<AnyCancellable>()
init(fooState: FooState) {
self.fooState = fooState
fooState.objectWillChange
.sink { [weak self] in
self?.objectWillChange.send()
}
.store(in: &cancellables)
}
}
let fooState = FooState()
let barState = BarState(fooState: fooState)
print(fooState.foo) // false
print(barState.bar) // false
fooState.foo = true
print(fooState.foo) // true
print(barState.bar) // true
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