TMButton.h

//
//  TMButton.h
//  TMButton
//
//  Created by 61 on 6/17/12.
//  Copyright (c) 2012 61. All rights reserved.
//

#import <Cocoa/Cocoa.h>

@interface TMButton : NSButton{
    NSTrackingArea *_trackingArea;
}

@property (nonatomic, strong) NSImage *originImage;
@property (nonatomic, strong) NSImage *hoverImage;
@end

TMButton.m

//
//  TMButton.m
//  TMButton
//
//  Created by 61 on 6/17/12.
//  Copyright (c) 2012 61. All rights reserved.
//

#import "TMButton.h"

@implementation TMButton
@synthesize originImage;
@synthesize hoverImage;

- (void)mouseEntered:(NSEvent *)theEvent
{
    [self setImage:self.hoverImage];
    [self display];
}

- (void)mouseExited:(NSEvent *)theEvent
{
    [self setImage:self.originImage];
    [self display];
}

- (void)updateTrackingAreas {
    [super updateTrackingAreas];
    
    if (_trackingArea)
    {
        [self removeTrackingArea:_trackingArea];
    }
    
    NSTrackingAreaOptions options = NSTrackingInVisibleRect | NSTrackingMouseEnteredAndExited | NSTrackingActiveAlways;
    _trackingArea = [[NSTrackingArea alloc] initWithRect:NSZeroRect options:options owner:self userInfo:nil];
    [self addTrackingArea:_trackingArea];
}

@end