NSView、设置BackgroundColor
NSView *view = [[NSView alloc] initWithFrame:NSMakeRect(100, 150, 100, 50)];
view.wantsLayer = YES;（很重要，不设置是否显示layer，默认是不显示，设置颜色也不会显示）
view.layer.backgroundColor = [NSColor blueColor].CGColor;（设置背景色要通过layer来设置）
[view setNeedsDisplay:YES];（可要也可不要）
[self.view addSubview:view];
NSButton 设置 BackgroundColor
方法一：
[[button cell] setBackgroundColor:[NSColor redColor]];
方法二：
+(NSImage *)swatchWithColor:(NSColor *)color size:(NSSize)size
{
NSImage *image = [[NSImage alloc] initWithSize:size];
[image lockFocus];
[color drawSwatchInRect:NSMakeRect(0, 0, size.width, size.height)];
[image unlockFocus];
return image;
}
NSImage *image = [NSImage swatchWithColor:[NSColor greenColor] size:button.frame.size]; [[button cell] setBackgroundColor:[NSColor redColor]];
button.image = image;
