Ios multitouch gestures11/30/2023 Now that we have an understanding of the touch events in iOS, let’s learn about gesture recognizers. the touch event happened inside the UIView imgTouchMe. The following code snippet shows an example of this: if ( (touch.LocationInView (this.View))) Additionally, we can test to see if that location is within a control by calling the method Frame.Contains. The method UITouch.LocationInView returns a CGPoint object that holds the coordinates of the touch within a given view. LblNumberOfFingers.Text = "Number of fingers: " + () To determine how many fingers touched the screen, use the Count property on the UITouch property: public override void TouchesBegan (NSSet touches, UIEvent evt) It is also possible to set multi-touch programmatically by setting the MultipleTouchEnabled property as shown in the following line of code: imgTouchMe.MultipleTouchEnabled = true Multi-touch can be enabled in the iOS Designer, as illustrated by the following screenshot: Multi-touch is not enabled by default on controls. This makes checking for a double tap as easy as checking the TapCount property, as illustrated in the following code: public override void TouchesBegan (NSSet touches, UIEvent evt) IOS automatically recognizes successive quick touches on the screen and will collect them all as one tap in a single UITouch object. UITouch touch = touches.AnyObject as UITouch To obtain a reference to the first touch, call the AnyObject property and cast it as a UITouch as show in the following example: public override void TouchesBegan (NSSet touches, UIEvent evt) We can use this property to obtain a reference to a touch, and determine the application’s response.Ĭlasses that override one of the touch events should first call the base implementation and then get the UITouch object associated with the event. The touch events get passed a touches property – an NSSet containing one or more touches. The UITouch object includes data about the touch, such as when the touch occurred, where it occurred, if the touch was a swipe, etc. They will first be called on the topmost UIView or UIViewController and then will be called on the UIView and UIViewControllers below them in the view hierarchy.Ī UITouch object will be created each time the user touches the screen. Touch events travel recursively down through the stack of UIViews, to check if the touch event is within the bounds of a view object. TouchesCancelled gets called if iOS cancels the touch – for example, if a user slides his or her finger away from a button to cancel a press.
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