我刚接触Xamarin.Forms和绑定的概念。请问为什么这段代码不起作用?当我点击按钮时,对象本身的名称会更改。但为什么Text属性没有更新呢?
var red = new Label
{
Text = todoItem.Name,
BackgroundColor = Color.Red,
Font = Font.SystemFontOfSize (20)
};
red.SetBinding (Label.TextProperty, "Name");
Button button = new Button
{
Text = String.Format("Tap for name change!")
};
button.Clicked += (sender, args) =>
{
_todoItem.Name = "Namie " + new Random().NextDouble();
};
todoItem是下面这个类的对象。通知本身可以工作,我几乎确定。我想我的绑定有问题,或者我对这个概念缺少了什么。
public class TodoItem : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
string _name;
public string Name
{
get { return _name; }
set
{
if (value.Equals(_name, StringComparison.Ordinal))
{
// Nothing to do - the value hasn't changed;
return;
}
_name = value;
OnPropertyChanged();
}
}
void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}