UIGestureRecognizer Constructors

Definition

Namespace:

UIKit

Assembly:

Xamarin.iOS.dll

Overloads

UIGestureRecognizer()	Default constructor that initializes a new instance of this class with no parameters.
UIGestureRecognizer(NSObjectFlag)	Constructor to call on derived classes to skip initialization and merely allocate the object.
UIGestureRecognizer(Action)	Initalizes a gesture recognizer.
UIGestureRecognizer(IntPtr)	A constructor used when creating managed representations of unmanaged objects; Called by the runtime.
UIGestureRecognizer(NSObject, Selector)	Initializes a designated gesture-recognizer.
UIGestureRecognizer(Selector, UIGestureRecognizer+Token)	Initalizes a gesture recognizer.

UIGestureRecognizer()

Default constructor that initializes a new instance of this class with no parameters.

[Foundation.Export("init")]
public UIGestureRecognizer ();

Attributes

ExportAttribute

Remarks

To add methods that will be invoked upon recognition, you can use the AddTarget method.

UIGestureRecognizer(NSObjectFlag)

Constructor to call on derived classes to skip initialization and merely allocate the object.

protected UIGestureRecognizer (Foundation.NSObjectFlag t);

new UIKit.UIGestureRecognizer : Foundation.NSObjectFlag -> UIKit.UIGestureRecognizer

Parameters

t

NSObjectFlag

Unused sentinel value, pass NSObjectFlag.Empty.

Remarks

This constructor should be called by derived classes when they completely construct the object in managed code and merely want the runtime to allocate and initialize the NSObject. This is required to implement the two-step initialization process that Objective-C uses, the first step is to perform the object allocation, the second step is to initialize the object. When developers invoke the constructor that takes the NSObjectFlag.Empty they take advantage of a direct path that goes all the way up to NSObject to merely allocate the object's memory and bind the Objective-C and C# objects together. The actual initialization of the object is up to the developer.

This constructor is typically used by the binding generator to allocate the object, but prevent the actual initialization to take place. Once the allocation has taken place, the constructor has to initialize the object. With constructors generated by the binding generator this means that it manually invokes one of the "init" methods to initialize the object.

It is the developer's responsibility to completely initialize the object if they chain up using the NSObjectFlag.Empty path.

In general, if the developer's constructor invokes the NSObjectFlag.Empty base implementation, then it should be calling an Objective-C init method. If this is not the case, developers should instead chain to the proper constructor in their class.

The argument value is ignored and merely ensures that the only code that is executed is the construction phase is the basic NSObject allocation and runtime type registration. Typically the chaining would look like this:

//
// The NSObjectFlag merely allocates the object and registers the
// C# class with the Objective-C runtime if necessary, but no actual
// initXxx method is invoked, that is done later in the constructor
//
// This is taken from Xamarin.iOS's source code:
//
[Export ("initWithFrame:")]
public UIView (System.Drawing.RectangleF frame) : base (NSObjectFlag.Empty)
{
// Invoke the init method now.
	var initWithFrame = new Selector ("initWithFrame:").Handle;
	if (IsDirectBinding)
		Handle = ObjCRuntime.Messaging.IntPtr_objc_msgSend_CGRect (this.Handle, initWithFrame, frame);
	else
		Handle = ObjCRuntime.Messaging.IntPtr_objc_msgSendSuper_CGRect (this.SuperHandle, initWithFrame, frame);
}

UIGestureRecognizer(Action)

Initalizes a gesture recognizer.

[ObjCRuntime.DesignatedInitializer]
public UIGestureRecognizer (Action action);

new UIKit.UIGestureRecognizer : Action -> UIKit.UIGestureRecognizer

Parameters

action

Action

Code to invoke when the gesture is recognized.

Attributes

DesignatedInitializerAttribute

UIGestureRecognizer(IntPtr)

A constructor used when creating managed representations of unmanaged objects; Called by the runtime.

protected internal UIGestureRecognizer (IntPtr handle);

new UIKit.UIGestureRecognizer : nativeint -> UIKit.UIGestureRecognizer

Parameters

handle

IntPtr

nativeint

Pointer (handle) to the unmanaged object.

Remarks

This constructor is invoked by the runtime infrastructure (GetNSObject(IntPtr)) to create a new managed representation for a pointer to an unmanaged Objective-C object. Developers should not invoke this method directly, instead they should call the GetNSObject method as it will prevent two instances of a managed object to point to the same native object.

UIGestureRecognizer(NSObject, Selector)

Initializes a designated gesture-recognizer.

[Foundation.Export("initWithTarget:action:")]
[ObjCRuntime.DesignatedInitializer]
public UIGestureRecognizer (Foundation.NSObject target, ObjCRuntime.Selector action);

new UIKit.UIGestureRecognizer : Foundation.NSObject * ObjCRuntime.Selector -> UIKit.UIGestureRecognizer

Parameters

target

NSObject

Recipient for action messages that are sent by the receiver.

action

Selector

Code to invoke when the gesture is recognized.

Attributes

ExportAttribute DesignatedInitializerAttribute

UIGestureRecognizer(Selector, UIGestureRecognizer+Token)

Initalizes a gesture recognizer.

public UIGestureRecognizer (ObjCRuntime.Selector sel, UIKit.UIGestureRecognizer.Token token);

new UIKit.UIGestureRecognizer : ObjCRuntime.Selector * UIKit.UIGestureRecognizer.Token -> UIKit.UIGestureRecognizer

Parameters

sel

Selector

A selector that specifies the method that is implemented by the target to handle the gesture that is recognized by the receiver.

token

UIGestureRecognizer.Token

String constant to be used as a token.