viewcontroller 初始化不同
IOS alloc init 会自动创建空view
mac alloc init不会主动创建，需重写-(void)loadview方法，否则会报nib找不到的错误：
Failed to set (contentViewController) user defined inspected property on (NSWindow): -[NSNib _initWithNibNamed:bundle:options:] could not load the nibName: HWVC1 in bundle (null).
解决：需重写-(void)loadview方法
-(void)loadView
{
NSRect frame=[[[NSApplication sharedApplication]mainWindow]frame];
self.view=[[NSView alloc]initWithFrame:frame];
}
