您可以在
NSWorkspace.sharedWorkspace().notificationCenter观察
NSWorkspaceDidActivateApplicationNotification钥匙时添加观察者。您将选择器指向您的一种方法，然后从
userInfo字典中获取信息。
AppDelegate中的简单示例：
斯威夫特2.2
func applicationDidFinishLaunching(notification: NSNotification) { NSWorkspace.sharedWorkspace().notificationCenter.addObserver(self, selector: #selector(activated), name: NSWorkspaceDidActivateApplicationNotification, object: nil)}func activated(notification: NSNotification) { if let info = notification.userInfo, app = info[NSWorkspaceApplicationKey], name = app.localizedName { print(name) }}迅捷3
func applicationDidFinishLaunching(_ aNotification: Notification) { NSWorkspace.shared().notificationCenter.addObserver(self, selector: #selector(activated(_:)), name: NSNotification.Name.NSWorkspaceDidActivateApplication, object: nil)}func activated(_ notification: NSNotification) { if let info = notification.userInfo, let app = info[NSWorkspaceApplicationKey] as? NSRunningApplication, let name = app.localizedName { print(name) }}
