gistfile1.txt

@interface ViewController : NSViewController


@end


@interface MyView : NSView

@property NSNumber * DrawnLineWidth;

@end





#import "ViewController.h"
@import QuartzCore;

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    MyView * v = [[MyView alloc] initWithFrame: CGRectMake (0, 0, 250, 250)];
    [self.view addSubview:v];
}

@end

@implementation MyView
{
    NSColor * color;
    NSBezierPath * path;
    NSNumber * drawnLineWidth;
}

- (BOOL)acceptsFirstResponder
{
    return YES;
}

- (instancetype)initWithFrame:(NSRect)frameRect
{
    if (!(self = [super initWithFrame:frameRect]))
        return nil;

    color = NSColor.blueColor;
    path = [[NSBezierPath alloc] init];
    [path moveToPoint:self.bounds.origin];
    [path lineToPoint:CGPointMake(self.bounds.size.width, self.bounds.size.height)];
    self.DrawnLineWidth = @1;
    
    self.wantsLayer = true;
    self.layer.backgroundColor = [[NSColor grayColor] CGColor];
    return self;
}

- (void)mouseDown:(NSEvent *)theEvent {
    [self animator].DrawnLineWidth = [[NSNumber alloc] initWithInt:(int)([self.DrawnLineWidth integerValue] + 10)];
}

- (void)setDrawnLineWidth:(NSNumber *) value {
    [self willChangeValueForKey:@"DrawnLineWidth"];
    drawnLineWidth = value;
    path.lineWidth = [value floatValue];
    [self setNeedsDisplay:YES];
    [self didChangeValueForKey:@"DrawnLineWidth"];
}

- (NSNumber *)DrawnLineWidth {
    return drawnLineWidth;
}

- (void)drawRect:(NSRect)dirtyRect
{
    [color setStroke];
    [path stroke];
}

+ (id)defaultAnimationForKey:(NSString *)key {
    if ([key isEqualToString:@"drawnLineWidth"]) {
        return [CABasicAnimation animation];
    } else {
        return [super defaultAnimationForKey:key];
    }
}

@end