我第一次限制 onAppearing()
选项卡式页面的所有子页面中的方法。我需要调用onAppearing()
当我更改标签时。为此,我使用 OnCurrentPageChanged()
调用onAppearing()
方法。
当我更改选项卡时,我正在调用 OnCurrentPageChanged()
并授予他们运行 onAppearing()
的权限功能。 onAppearing()
在调用 OnCurrentPageChanged()
之前调用.
分页码:
public partial class VendorScheduleTabbedPage : Xamarin.Forms.TabbedPage
{
public int isCount;
public VendorScheduleTabbedPage ()
{
InitializeComponent ();
Xamarin.Forms.Application.Current.Properties["dayOnAppear"] = false;
Xamarin.Forms.Application.Current.Properties["weekOnAppear"] = false;
Xamarin.Forms.Application.Current.Properties["monthOnAppear"] = false;
On<Android>().SetBarItemColor(value: Color.FromHex("#6699FF"));
On<Android>().SetBarSelectedItemColor(value: Color.Orange);
}
override protected void OnCurrentPageChanged()
{
isCount = 1;
if (this.CurrentPage.Title == "Week")
{
Xamarin.Forms.Application.Current.Properties["weekOnAppear"] = true;
}
if (this.CurrentPage.Title == "Month")
{
Xamarin.Forms.Application.Current.Properties["monthOnAppear"] = true;
}
else
{
Xamarin.Forms.Application.Current.Properties["dayOnAppear"] = true;
}
base.OnCurrentPageChanged();
}
}
}
周页码(子页):
public WeekSchedulePage()
{
InitializeComponent();
NavigationPage.SetHasNavigationBar(this, false);
timeSlot = new List<VendorScheduleTimeSlot>();
scheduleSlots = new List<VendorScheduleTimeSlot>();
lstVendorsData = new List<ScheduledCustomersVM>();
SortedList = new List<ScheduledCustomersVM>();
scheduledCustomersList = new List<ScheduledCustomersVM>();
rescheduledCustomersList = new List<RescheduledCustomersVM>();
ConfirmBtn.IsVisible = true;
ConfirmBtn.IsEnabled = false;
vendorDayAndHoursDataVM = new VendorDayAndHoursDataVM();
lstDaysAndHours = new List<VendorDayAndHoursDataVM>();
lstQuestionsData = new List<VendorQuestionsDataVM>();
overlay.IsVisible = false;
Alert.IsVisible = false;
presentWeekDay.Text = DateTime.Now.ToString("dddd, dd MMMM yyyy");
currentDayName = DateTime.Now.DayOfWeek.ToString();
currentDate = DateTime.Parse(presentWeekDay.Text);
}
protected override void OnAppearing()
{
var isAppear = Convert.ToBoolean(Application.Current.Properties["weekOnAppear"].ToString());
if (isAppear == true)
{
ConfirmBtn.IsVisible = true;
ConfirmBtn.IsEnabled = false;
overlay.IsVisible = false;
Alert.IsVisible = false;
Application.Current.Properties["dayOnAppear"] = true;
Application.Current.Properties["monthOnAppear"] = true;
ConfirmBtn.IsEnabled = false;
scheduledCustomersList.Clear();
rescheduledCustomersList.Clear();
presentWeekDay.Text = DateTime.Now.ToString("dddd, dd MMMM yyyy");
currentDayName = DateTime.Now.DayOfWeek.ToString();
weekwiseTimeslotClick();
base.OnAppearing();
}
}
这里我需要调用
OnCurrentPageChanged()
方法优先而不是 OnApearing()
方法。和OnCurrentPageChanged()
会给bool
执行 OnApearing()
中的代码的值方法。
最佳答案
在 Android 中,onAppearing
在 OnCurrentPageChanged
之前调用在 iOS 中 OnCurrentPageChanged
在 onAppearing
之前调用.
1.作为jgoldberger
建议,可以在CurrentPageChanged
之后的每个Page中调用方法:
override protected void OnCurrentPageChanged()
{
if (this.CurrentPage.Title == "Week")
{
Xamarin.Forms.Application.Current.Properties["weekOnAppear"] = true;
NavigationPage naviPage = this.Children[0] as NavigationPage;
WeekPage page = naviPage.RootPage as WeekPage;
page.test();
}else if (this.CurrentPage.Title == "Month")
{
Xamarin.Forms.Application.Current.Properties["monthOnAppear"] = true;
NavigationPage naviPage = this.Children[1] as NavigationPage;
MonthPage page = naviPage.RootPage as MonthPage;
page.test();
}
else
{
Xamarin.Forms.Application.Current.Properties["dayOnAppear"] = true;
NavigationPage naviPage = this.Children[2] as NavigationPage;
DayPage page = naviPage.RootPage as DayPage;
page.test();
}
base.OnCurrentPageChanged();
}
}
2.您可以使用messaging-center通知特定页面在
CurrentPageChanged
之后执行一些操作: override protected void OnCurrentPageChanged()
{
string testStr;
if (this.CurrentPage.Title == "Week")
{
testStr = "Week";
}else if (this.CurrentPage.Title == "Month")
{
testStr = "Month";
}
else
{
testStr = "Day";
}
MessagingCenter.Send<object, string>(new object(), "CurrentPageChanged", testStr);
base.OnCurrentPageChanged();
}
并且在每一页中:
public partial class MonthPage : ContentPage
{
public MonthPage()
{
InitializeComponent();
MessagingCenter.Subscribe<object, string>(new object(), "CurrentPageChanged", async (sender, arg) =>
{
if (arg == "Month")
{
Console.WriteLine(arg);
//do something
}
});
}
public void test() {
Console.WriteLine("test");
//do something
}
}
顺便说一句,你应该使用
if...else if...else
而不是 if...if...else
在您的控制语句中。
关于xamarin - OnAppearing() 方法在调用 OnCurrentPageChanged() 方法之前执行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/59409853/