mouseEntered y mouseExited no llamados en NSImageView SubClass

Question

Creé una subclase de NSImageView para capturar los eventos mouseEntered y mouseExited. Pero solo se llaman los eventos mouseUp y mouseDown. Cómo capturar los eventos mouseEntered y mouseExited en la subclase NSImageView?

Answer 1

Si desea utilizar mouseEntered: y mouseExited: Debe usar NSTrackingArea. Aquí está la referencia NSTrackingArea Class Reference.

Ejemplo:

//Add this to Your imageView subclass 

-(void)mouseEntered:(NSEvent *)theEvent { 
    NSLog(@"Mouse entered"); 
} 

-(void)mouseExited:(NSEvent *)theEvent 
{ 
    NSLog(@"Mouse exited"); 
} 

-(void)updateTrackingAreas 
{ 
    [super updateTrackingAreas]; 
    if(trackingArea != nil) { 
     [self removeTrackingArea:trackingArea]; 
     [trackingArea release]; 
    } 

    int opts = (NSTrackingMouseEnteredAndExited | NSTrackingActiveAlways); 
    trackingArea = [ [NSTrackingArea alloc] initWithRect:[self bounds] 
               options:opts 
                owner:self 
               userInfo:nil]; 
    [self addTrackingArea:trackingArea]; 
} 

Answer 2

Swift 3 Versión de respuesta @Justin Boo 's:

private var trackingArea: NSTrackingArea? 

override func updateTrackingAreas() { 
    if let trackingArea = self.trackingArea { 
     self.removeTrackingArea(trackingArea) 
    } 

    let options: NSTrackingAreaOptions = [.mouseEnteredAndExited, .activeAlways] 
    let trackingArea = NSTrackingArea(rect: self.bounds, options: options, owner: self, userInfo: nil) 
    self.addTrackingArea(trackingArea) 
}