NSWindow+Fade - Animator proxy based NSWindow fading

NSWindow+Fade.h

@interface NSWindow (Fade)
- (IBAction)fadeIn:(id)sender;
- (IBAction)fadeOut:(id)sender;
@end

NSWindow+Fade.m

#import "NSWindow+SNRAdditions.h"

#define kWindowAnimationDuration 0.1f

@implementation NSWindow (Fade)
- (IBAction)fadeIn:(id)sender
{
    [self setAlphaValue:0.f];
    [self makeKeyAndOrderFront:nil];
    [NSAnimationContext beginGrouping];
    [[NSAnimationContext currentContext] setDuration:kWindowAnimationDuration];
    [[self animator] setAlphaValue:1.f];
    [NSAnimationContext endGrouping];
}

- (IBAction)fadeOut:(id)sender
{
    [NSAnimationContext beginGrouping];
    __block __unsafe_unretained NSWindow *bself = self;
    [[NSAnimationContext currentContext] setDuration:kWindowAnimationDuration];
    [[NSAnimationContext currentContext] setCompletionHandler:^{
        [bself orderOut:nil];
        [bself setAlphaValue:1.f];
    }];
    [[self animator] setAlphaValue:0.f];
    [NSAnimationContext endGrouping];
}
@end

Swift 4 version: https://gist.github.com/BenLeggiero/1ec89e5979bf88ca13e2393fdab15ecc