如何在SwiftUI中订阅数组的大小

Question

我想跟踪数组的大小，我认为这样的东西会起作用：

class CarListViewModel: ObservableObject {
private var cancellables = Set<AnyCancellable>()   
@Published var ownedCarLength = 0
init(){     
CarRepository.$ownedCars.sink { _ in
self.ownedCarLength = CarRepository.ownedCars.count
}
.store(in: &cancellables)
}

因为每次修改数组CarRepository.ownedCars时都会调用此函数，但是由于某种原因，从CarRepository.ownedCars.count返回的值计算为0。有更干净的方法吗？

Answer 1

很难知道CarRepository和CarRepository.ownedCars是什么，但我猜它们是这样的：

class CarRepositoryType: ObservableObject {
@Published var ownedCars = []
}
var CarRepository = CarRepositoryType()

在更新ownedCars之前调用接收器。将新值传递给接收器；你应该在那里读。

CarRepository.$ownedCars.sink { owned in
self.ownedCarLength = owned.count
}