当我从主屏幕按下图标但它已经是 运行 时，应用会发生什么情况？
What happens to the app when I press the icon from home screen but it is already running?
假设您正在使用一个应用程序，然后按下主页按钮。该应用程序已经 运行，但您不可见。然后，您再次按下该应用程序图标可将该应用程序带回最前面。
代码中调用了什么？在 ViewController 中调用什么？
//In appDelegate class following delegate method called when you hit home button
func applicationWillResignActive(application: UIApplication)
{
}
// this EnterBackground delegate is called
func applicationDidEnterBackground(application: UIApplication)
{
}
//When you tap on app icon again following 2 delegate methods called
func applicationWillEnterForeground(application: UIApplication)
{
}
//finally when your app become active
func applicationDidBecomeActive(application: UIApplication)
{
}
//This called when app terminates
func applicationWillTerminate(application: UIApplication)
{
}
This is called life cycle of app.
您有一个名为 AppDelegate.swift 的文件。在那里你可以找到默认的 5 种方法。
如你所见，调用函数时已经有一个很好的描述：
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]!) -> Bool {
//Called if the app is started
return true
}
func applicationWillResignActive(application: UIApplication) {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
func applicationDidEnterBackground(application: UIApplication) {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
func applicationWillEnterForeground(application: UIApplication) {
// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}
func applicationDidBecomeActive(application: UIApplication) {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
func applicationWillTerminate(application: UIApplication) {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
// Saves changes in the application's managed object context before the application terminates.
}
假设您正在使用一个应用程序，然后按下主页按钮。该应用程序已经 运行，但您不可见。然后，您再次按下该应用程序图标可将该应用程序带回最前面。
代码中调用了什么？在 ViewController 中调用什么？
//In appDelegate class following delegate method called when you hit home button
func applicationWillResignActive(application: UIApplication)
{
}
// this EnterBackground delegate is called
func applicationDidEnterBackground(application: UIApplication)
{
}
//When you tap on app icon again following 2 delegate methods called
func applicationWillEnterForeground(application: UIApplication)
{
}
//finally when your app become active
func applicationDidBecomeActive(application: UIApplication)
{
}
//This called when app terminates
func applicationWillTerminate(application: UIApplication)
{
}
This is called life cycle of app.
您有一个名为 AppDelegate.swift 的文件。在那里你可以找到默认的 5 种方法。
如你所见，调用函数时已经有一个很好的描述：
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]!) -> Bool {
//Called if the app is started
return true
}
func applicationWillResignActive(application: UIApplication) {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
func applicationDidEnterBackground(application: UIApplication) {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
func applicationWillEnterForeground(application: UIApplication) {
// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}
func applicationDidBecomeActive(application: UIApplication) {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
func applicationWillTerminate(application: UIApplication) {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
// Saves changes in the application's managed object context before the application terminates.
}