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MonoTouch Events
If you want to intercept events from UIControl, you have a range of options: from using the C# lambdas and delegate functions to using the low-level Objective-C APIs.
The following shows how you would capture the TouchDown event on a button, depending on how much control you need:
C# Style
Using the delegate syntax:
UIButton button = MakeTheButton ();
button.TouchDown += delegate {
Console.WriteLine ("Touched");
};
If you like lambdas instead:
button.TouchTown += () => {
Console.WriteLine ("Touched");
};
If you want to have multiple buttons use the same handler to share the same code:
void handler (object sender, EventArgs args)
{
if (sender == button1)
Console.WriteLine ("button1");
else
Console.WriteLine ("some other button");
}
button1.TouchDown += handler;
button2.TouchDown += handler;
Monitoring more than one kind of Event
The C# events for UIControlEvent flags have a one to one mapping to individual flags. Sometimes you might want to have the same piece of code handle two or more events, in that case, use the UIControl.AddTarget method:
button.AddTarget (handler, UIControlEvent.TouchDown | UIControl.TouchCancel);
Using the lambda syntax:
button.AddTarget (()=> Console.WriteLine ("An event happened"), UIControlEvent.TouchDown | UIControl.TouchCancel);
If you need to use low-level features of Objective-C, like hooking up to a particular object instance and invoke a particular selector:
[Export ("MySelector")]
void MyObjectiveCHandler ()
{
Console.WriteLine ("Hello!");
}
// In some other place:
button.AddTarget (this, new Selector ("MySelector"), UIControlEvent.TouchDown);