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objective-ccocoamacostrackpad

Mac cocoa - how can i detect trackpad scroll gestures?

I want to detect scroll gestures (two fingers on trackpad). How should i do that?

Solution

  • You should do that by implementing touch event methods of NSView in your custom subclass. These methods are :

    - (void)touchesBeganWithEvent:(NSEvent *)event;
- (void)touchesMovedWithEvent:(NSEvent *)event;
- (void)touchesEndedWithEvent:(NSEvent *)event;
- (void)touchesCancelledWithEvent:(NSEvent *)event;

    The NSEvent object coming along as a paramter contains informations about the touches involded. In particular, you may retrieve them using :

    -(NSSet *)touchesMatchingPhase:(NSTouchPhase)phase inView:(NSView *)view;

    Also, in the custom view subclass, you must first set it like this :

    [self setAcceptsTouchEvents:YES];

    in order to recieve such events.