async display kit -- AsControlNode states

PRImageNode.m

#import "PRImageNode.h"
#import <AsyncDisplayKit/ASControlNode+Subclasses.h>

@interface PRImageNode(){
    // PRImageNode class is derived from ASImageNode which derived from ASControlNode
    BOOL _touched;
}
@end


@implementation PRImageNode

-(id)init{
    
    if( !( self = [super init] ) )
        return nil;
    
    return self;
}

-(void) makeTouched{
    self.borderWidth = 5;
    self.borderColor = [UIColor blackColor].CGColor;
    self.cornerRadius = 3;
}

-(void) cancelTouched{
    self.borderWidth = 0;
    self.cornerRadius = 0;
}


-(BOOL)beginTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)touchEvent{
    _touched = true;
    [self makeTouched];
    return YES;
}


-(BOOL)continueTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)touchEvent{
    
    CGPoint touchLocation = [touch locationInView:self.view];
    if( CGRectContainsPoint(self.bounds, touchLocation) ){
        if( !_touched ){
            _touched = true;
            [self makeTouched];
        }
    }else{
        [self cancelTrackingWithEvent:touchEvent];
        _touched = false;
        [self cancelTouched];
    }
    return YES;
}


-(void)endTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)touchEvent{
    _touched = false;
    [self cancelTouched];
}

@end