| Inherits from | |
| Conforms to | |
| Framework | /System/Library/Frameworks/UIKit.framework |
| Availability | Available in iPhone OS 2.0 and later. |
| Declared in | UITouch.h |
| Related sample code |
A UITouch object represents the presence or movement of a finger on the screen for a particular event. You access UITouch objects through UIEvent objects passed into responder objects for event handling.
A UITouch object includes methods for accessing the view or window in which the touch occurred and for obtaining the location of the touch in a specific view or window. it also lets you find out when the touch occurred, whether the user tapped more than once, whether the finger is swiped (and if so, in which direction), and the phase of a touch—that is, whether it began, moved, or ended the gesture, or whether it was canceled.
A UITouch object is persistent throughout a multi-touch sequence. You should never retain an UITouch object when handling an event. If you need to keep information about a touch from one phase to another, you should copy that information from the UITouch object.
See Event Handling in iPhone Application Programming Guide for further information on event handling.
– locationInView:
– previousLocationInView:
view property
window property
For more about Objective-C properties, see “Properties” in The Objective-C Programming Language.
The type of touch. (read-only)
@property(nonatomic, readonly) UITouchPhase phase
The property value is a constant that indicates whether the touch began, moved, ended, or was canceled. For descriptions of possible UITouchPhase values, see “Touch Phase.”
UITouch.hThe number of times the finger was tapped for this given touch. (read-only)
@property(nonatomic, readonly) NSUInteger tapCount
The value of this property is an integer indicating the number of times the user tapped their fingers on a certain point within a predefined period. If want to determine whether the user single-tapped, double-tapped, or even triple-tapped a particular view or window, you should evaluate the value returned by this method.
UITouch.hThe time when the touch occurred or when it was last mutated. (read-only)
@property(nonatomic, readonly) NSTimeInterval timestamp
The value of this property is the time, in seconds, since system startup the touch either originated or was last changed. You can store and compare the initial value of this attribute to subsequent timestamp values of the UITouch instance to determine the duration of the touch and, if it is being swiped, the speed of movement.
UITouch.hThe view in which the touch initially occurred. (read-only)
@property(nonatomic, readonly, retain) UIView *view
The value of the property is the view object in which the touch originally occurred. This object might not be the view the touch is currently in.
UITouch.hThe window in which the touch initially occurred. (read-only)
@property(nonatomic, readonly, retain) UIWindow *window
The value of the property is the window object in which the touch originally occurred. This object might not be the window the touch is currently in.
UITouch.hReturns the current location of the receiver in the coordinate system of the given view.
- (CGPoint)locationInView:(UIView *)view
The view object in whose coordinate system you want the touch located. A custom view that is handling the touch may specify self to get the touch location in its own coordinate system. Pass nil to get the touch location in the window’s coordinates.
A point specifying the location of the receiver in view.
This method returns the current location of a UITouch object in the coordinate system of the specified view. Because the touch object might have been forwarded to a view from another view, this method performs any necessary conversion of the touch location to the coordinate system of the specified view.
UITouch.hReturns the previous location of the receiver in the coordinate system of the given view.
- (CGPoint)previousLocationInView:(UIView *)view
The view object in whose coordinate system you want the touch located. A custom view that is handling the touch may specify self to get the touch location in its own coordinate system. Pass nil to get the touch location in the window’s coordinates.
This method returns the previous location of a UITouch object in the coordinate system of the specified view. Because the touch object might have been forwarded to a view from another view, this method performs any necessary conversion of the touch location to the coordinate system of the specified view.
UITouch.hThe phase of a finger touch.
typedef enum {
UITouchPhaseBegan,
UITouchPhaseMoved,
UITouchPhaseStationary,
UITouchPhaseEnded,
UITouchPhaseCancelled,
} UITouchPhase;
UITouchPhaseBeganA finger for a given event touched the screen.
Available in iPhone OS 2.0 and later.
Declared in UITouch.h.
UITouchPhaseMovedA finger for a given event moved on the screen.
Available in iPhone OS 2.0 and later.
Declared in UITouch.h.
UITouchPhaseStationaryA finger is touching the surface but hasn't moved since the previous event.
Available in iPhone OS 2.0 and later.
Declared in UITouch.h.
UITouchPhaseEndedA finger for a given event was lifted from the screen.
Available in iPhone OS 2.0 and later.
Declared in UITouch.h.
UITouchPhaseCancelledThe system cancelled tracking for the touch, as when (for example) the user puts the device to his or her face.
Available in iPhone OS 2.0 and later.
Declared in UITouch.h.
The phase of a UITouch instance changes in a certain order during the course of an event. You access this value through the phase property.
UITouch.hLast updated: 2008-09-09
iPhone OS Reference Library Data Management: Event Handling UITouch Class Reference