如何在按钮(Objective-C)上设置自定义指针效果？

#import <Cocoa/Cocoa.h>

@interface CustomButton : NSButton

@end

@implementation CustomButton

- (instancetype)initWithFrame:(NSRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self addTrackingArea:[[NSTrackingArea alloc] initWithRect:self.bounds options:NSTrackingMouseEnteredAndExited|NSTrackingActiveAlways owner:self userInfo:nil]];
    }
    return self;
}

- (void)mouseEntered:(NSEvent *)event {
    NSCursor *customCursor = [[NSCursor alloc] initWithImage:[NSImage imageNamed:@"customCursor.png"] hotSpot:NSMakePoint(0, 0)];
    [customCursor set];
}

- (void)mouseExited:(NSEvent *)event {
    [[NSCursor arrowCursor] set];
}

@end