c# - MonoTouch.Dialog - 接受空值作为输入的 DateElement
<p><p>我在互联网上搜索无济于事...我正在使用 MT.D 并想为使用 <code>DateElement</code> 的人设置生日，但生日可能为空，这意味着数据尚未收集。有人知道如何让 DateElement 接受空值或日期吗？</p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p><strong>更新</strong> 20140106:<em>自从 iOS7 发布以来，Apple 希望日期/时间选择器与内容一致，而不是作为操作表，或者在本例中为全屏覆盖。因此，此代码仅用于说明和历史目的。</em></p>
<p>好的，所以我推出了自己的类(class)。就我个人而言，我认为当前的日期/时间选择器设置看起来并不像弹出一个带有日期选择器的 <code>ActionSheet</code> 等效项那样专业。在 MT.D 方面经验更丰富的人可能能够弄清楚，但我所做的是从 <code>DateTimeElement</code> 和 <code>DateElement</code> 复制代码并对其进行修改，使其具有三个顶部按钮:最左边的按钮是取消，右边的按钮区域有“设置”和“空”按钮。右侧按钮的标题可以在类的ctor中设置为您喜欢的任何内容，但可以默认为“设置日期”和“无日期”。</p>
<p>分享就是关怀!</p>
<p><strong>可为空的日期时间元素</strong></p>
<pre><code>using MonoTouch.Foundation;
using MonoTouch.UIKit;
using System;
using System.Drawing;
namespace MonoTouch.Dialog
{
public class NullableDateTimeElement : StringElement
{
private class MyViewController : UIViewController
{
private NullableDateTimeElement container;
private bool hasNullValue = false;
private bool hasBeenSet = false;
//private EventHandler nullButtonTouched;
//UIButton isNullButton;
public bool Autorotate
{
get;
set;
}
public MyViewController (NullableDateTimeElement container)
{
this.container = container;
}
public override void ViewDidLoad ()
{
base.ViewDidLoad ();
//isNullButton = UIButton.FromType (UIButtonType.RoundedRect);
//isNullButton.SizeToFit ();
//isNullButton.Frame = new RectangleF(this.View.Frame.Top, this.View.Frame.Left, this.View.Frame.Width - 40f, 40f);
//isNullButton.SetTitle (container.NullButtonCaption, UIControlState.Normal);
this.NavigationItem.RightBarButtonItems = new UIBarButtonItem[]
{
new UIBarButtonItem(container.NullButtonCaption, UIBarButtonItemStyle.Done, NullButtonTapped),
new UIBarButtonItem(container.SetButtonCaption, UIBarButtonItemStyle.Done, SetButtonTapped)
};
this.NavigationItem.LeftBarButtonItem = new UIBarButtonItem(UIBarButtonSystemItem.Cancel, CancelTapped);
this.NavigationItem.HidesBackButton = true;
//this.View.AddSubview (isNullButton);
//this.isNullButton.TouchUpInside += (nullButtonTouched = new EventHandler(nullButtonWasTouched));
}
void CancelTapped(object sender, EventArgs e)
{
hasBeenSet = false;
this.NavigationController.PopViewControllerAnimated (true);
}
void NullButtonTapped(object sender, EventArgs e)
{
hasBeenSet = true;
hasNullValue = true;
this.NavigationController.PopViewControllerAnimated (true);
}
void SetButtonTapped(object sender, EventArgs e)
{
hasBeenSet = true;
hasNullValue = false;
this.NavigationController.PopViewControllerAnimated (true);
}
public override void ViewWillDisappear (bool animated)
{
base.ViewWillDisappear (animated);
if (hasBeenSet)
{
if (!hasNullValue)
this.container.DateValue = this.container.datePicker.Date;
else
this.container.DateValue = null;
}
//this.isNullButton.TouchUpInside -= nullButtonTouched;
//nullButtonTouched = null;
}
/*void nullButtonWasTouched(object sender, EventArgs e)
{
hasNullValue = true;
NavigationController.PopViewControllerAnimated (true);
}*/
public override void DidRotate (UIInterfaceOrientation fromInterfaceOrientation)
{
base.DidRotate (fromInterfaceOrientation);
this.container.datePicker.Frame = NullableDateTimeElement.PickerFrameWithSize (this.container.datePicker.SizeThatFits (SizeF.Empty));
}
public override bool ShouldAutorotateToInterfaceOrientation (UIInterfaceOrientation toInterfaceOrientation)
{
return this.Autorotate;
}
}
public DateTime? DateValue;
public UIDatePicker datePicker;
//public UIButton isNullButton;
public string NullButtonCaption { get; set; }
public string SetButtonCaption { get; set; }
protected internal NSDateFormatter fmt = new NSDateFormatter
{
DateStyle = NSDateFormatterStyle.Short
};
public NullableDateTimeElement (string caption, DateTime? date, string nullButtonCaption, string setButtonCaption) : base (caption)
{
this.DateValue = date;
this.Value = this.FormatDate (date);
this.NullButtonCaption = nullButtonCaption;
this.SetButtonCaption = setButtonCaption;
}
public NullableDateTimeElement(string caption, DateTime? date, string nullButtonCaption) : this(caption, date, nullButtonCaption, "Set Date")
{}
public NullableDateTimeElement(string caption, DateTime? date) : this(caption, date, "No Date", "Set Date")
{}
public override UITableViewCell GetCell (UITableView tv)
{
this.Value = this.FormatDate (this.DateValue);
UITableViewCell cell = base.GetCell (tv);
cell.Accessory = UITableViewCellAccessory.DisclosureIndicator;
return cell;
}
protected override void Dispose (bool disposing)
{
base.Dispose (disposing);
if (disposing)
{
if (this.fmt != null)
{
this.fmt.Dispose ();
this.fmt = null;
}
/* if (this.isNullButton != null)
{
this.isNullButton.Dispose ();
this.isNullButton = null;
}*/
if (this.datePicker != null)
{
this.datePicker.Dispose ();
this.datePicker = null;
}
}
}
public virtual string FormatDate (DateTime? dt)
{
if (dt.HasValue)
return this.fmt.ToString (dt.Value) + " " + dt.Value.ToLocalTime ().ToShortTimeString ();
else
return NullButtonCaption;
}
public virtual UIDatePicker CreatePicker ()
{
return new UIDatePicker (RectangleF.Empty)
{
AutoresizingMask = UIViewAutoresizing.FlexibleWidth,
Mode = UIDatePickerMode.DateAndTime,
Date = this.DateValue ?? DateTime.Now
};
}
private static RectangleF PickerFrameWithSize (SizeF size)
{
RectangleF applicationFrame = UIScreen.MainScreen.ApplicationFrame;
float y = 0f;
float x = 0f;
switch (UIApplication.SharedApplication.StatusBarOrientation)
{
case UIInterfaceOrientation.Portrait:
case UIInterfaceOrientation.PortraitUpsideDown:
{
x = (applicationFrame.Width - size.Width) / 2f;
y = (applicationFrame.Height - size.Height) / 2f - 25f;
break;
}
case UIInterfaceOrientation.LandscapeRight:
case UIInterfaceOrientation.LandscapeLeft:
{
x = (applicationFrame.Height - size.Width) / 2f;
y = (applicationFrame.Width - size.Height) / 2f - 17f;
break;
}
}
return new RectangleF (x, y, size.Width, size.Height);
}
public override void Selected (DialogViewController dvc, UITableView tableView, NSIndexPath path)
{
NullableDateTimeElement.MyViewController myViewController = new NullableDateTimeElement.MyViewController (this)
{
Autorotate = dvc.Autorotate
};
this.datePicker = this.CreatePicker ();
this.datePicker.Frame = NullableDateTimeElement.PickerFrameWithSize (this.datePicker.SizeThatFits (SizeF.Empty));
myViewController.View.BackgroundColor = UIColor.Black;
myViewController.View.AddSubview (this.datePicker);
dvc.ActivateController (myViewController);
}
}
}
</code></pre>
<p><strong>NULLABLE DATE-ONLY ELEMENT</strong></p>
<pre><code>using System;
using MonoTouch.Foundation;
using MonoTouch.UIKit;
namespace MonoTouch.Dialog
{
public class NullableDateElement : NullableDateTimeElement
{
public NullableDateElement (string caption, DateTime? date, string nullButtonCaption, string setButtonCaption) : base (caption, date, nullButtonCaption, setButtonCaption)
{
initDateOnlyPicker ();
}
public NullableDateElement (string caption, DateTime? date, string nullButtonCaption) : base(caption, date, nullButtonCaption)
{
initDateOnlyPicker ();
}
public NullableDateElement (string caption, DateTime? date) : base(caption, date)
{
initDateOnlyPicker ();
}
void initDateOnlyPicker()
{
this.fmt.DateStyle = NSDateFormatterStyle.Medium;
}
public override string FormatDate (DateTime? dt)
{
if (dt.HasValue)
return this.fmt.ToString (dt);
else
return base.NullButtonCaption;
}
public override UIDatePicker CreatePicker ()
{
UIDatePicker uIDatePicker = base.CreatePicker ();
uIDatePicker.Mode = UIDatePickerMode.Date;
return uIDatePicker;
}
}
}
</code></pre>
<p>@Miguel，请考虑将此添加到 MonoTouch.Dialog，因为对于空日期/日期时间存在非常合理的业务需求，并且此解决方案似乎可以解决问题。我的代码需要稍微清理一下，但这可行。</p></p>
<p style="font-size: 20px;">关于c# - MonoTouch.Dialog - 接受空值作为输入的 DateElement，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/10199084/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/10199084/
</a>
</p>
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