[英]SwiftUI ContentView_Previews not running function
I'm trying to generate some mock data for my preview in Xcode with a method written directly in ContentView_Previews
but I have no success and I don't understand why.我正在尝试使用直接在
ContentView_Previews
中编写的方法为我在 Xcode 中的预览生成一些模拟数据,但我没有成功,我不明白为什么。
struct ContentView_Previews: PreviewProvider {
static let healthManager = generateMockData()
static var previews: some View {
MainView().environmentObject(healthManager)
}
static func generateMockData() -> HealthManager {
let defaultHealthManager = HealthManager()
defaultHealthManager.gavePermissions = true
for i in 1...10 {
let defaultWorkout = HKWorkout(activityType: .traditionalStrengthTraining,
start: .now - Double(i * 50),
end: .now,
duration: Double(i * 100),
totalEnergyBurned: HKQuantity(unit: .largeCalorie(), doubleValue: Double(i * 100)),
totalDistance: nil,
device: nil,
metadata: nil)
defaultHealthManager.previousWorkouts.append(defaultWorkout)
}
return defaultHealthManager
}
}
Basically it shows up defaultHealthManager
object has no values set besides the default ones.基本上它显示
defaultHealthManager
object 除了默认值之外没有设置任何值。 If I call ContentView_Previews. generateMockData()
如果我调用
ContentView_Previews. generateMockData()
ContentView_Previews. generateMockData()
for my property in the actual view at runtime, it works fine.在运行时的实际视图中为我的属性
ContentView_Previews. generateMockData()
,它工作正常。
On occasion, I seem to need to create what I call an intermediary view to get things to work.有时,我似乎需要创建我称之为中间视图的东西来让事情正常进行。 Does something like this work?
这样的东西有用吗?
struct MainViewIntermediary: View {
@State var healthManager: HealthManager
init() {
let defaultHealthManager = HealthManager()
defaultHealthManager.gavePermissions = true
for i in 1...10 {
let defaultWorkout = HKWorkout(activityType: .traditionalStrengthTraining,
start: .now - Double(i * 50),
end: .now,
duration: Double(i * 100),
totalEnergyBurned: HKQuantity(unit: .largeCalorie(), doubleValue: Double(i * 100)),
totalDistance: nil,
device: nil,
metadata: nil)
defaultHealthManager.previousWorkouts.append(defaultWorkout)
_healthManager = State(initialValue: defaultHealthManager)
}
}
var body: some View {
MainView().environmentObject(healthManager)
}
}
Then your preview provider becomes:然后你的预览提供者变成:
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
MainViewIntermediary()
}
}
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