我已经知道如何保存内容,并且可以在打开应用程序时自动加载它们。但我不知道如何在关闭时拯救它们!我现在有一个按钮。我试图仅保存一个值,StreakNumber
。然而,每当我尝试时,我都会失败。
当在应用程序委托(delegate)中时,我尝试说ViewController.AppSave(ViewController)
。我收到错误:
Editor placeholder in source file Expression resolves to an unused function
如果我使用ViewController.AppSave()
我收到以下错误:
Instance member 'SaveApp' cannot be used on type 'ViewController'; did you mean to use a value of this type instead?
import UIKit
import UserNotifications
class ViewController: UIViewController {
//TEST PLAY AREA//
@IBAction func SaveButton(_ sender: Any) {
SaveApp()
}
@IBAction func LoadButton(_ sender: Any) {
LoadApp()
}
///TEST PLAY AREA ENDS
public var streakNumber = 0
public var streakNumberString = ""
public var activated = false
let defaults = UserDefaults.standard
//Labels
@IBOutlet var streakNumberLabel: UILabel!
@IBOutlet var remainingTimeTextLabel: UILabel!
@IBOutlet var remainingTimeNumberLabel: UILabel!
//Buttons
@IBAction func startButton(_ sender: Any) {
Activate()
}
@IBAction func stopButton(_ sender: Any) {
Deactivate()
seconds = 59
minutes = 59
hours = 47
}
//Timer
var timer = Timer()
var seconds = 0
var minutes = 0
var hours = 0
// Nitifications
//END
override func viewDidLoad() {
super.viewDidLoad()
LoadApp()
// this enables notifications
UNUserNotificationCenter.current().requestAuthorization(options:[.alert , .sound , .badge], completionHandler:{ didAllow, error in
})
}
func Activate (){
if activated == false {
streakNumber += 1
}
activated = true
streakNumberLabel.text = String(streakNumber)
}
func Deactivate (){
if activated == true{
activated = false
ActivTimer()
// Notification
let content = UNMutableNotificationContent()
content.title = " 10 secodns are up "
content.subtitle = " yep time passed"
content.body = " The 10 seconds are really up!!"
content.badge = 1
let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 600, repeats:false)
let request = UNNotificationRequest(identifier: "timerDone", content: content , trigger: trigger)
UNUserNotificationCenter.current().add(request,withCompletionHandler:nil)
}
}
@objc func Clock(){
seconds = seconds-1
if seconds == -1{
seconds = 59
minutes = minutes-1
}
if minutes == -1{
minutes = 59
hours = hours-1
}
remainingTimeNumberLabel.text = (String(hours) + ":" + String(minutes) + ":" + String(seconds))
if seconds == 0 && hours == 0 && minutes == 0 {
timer.invalidate()
}
}
func ActivTimer(){
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(ViewController.Clock), userInfo: nil, repeats: true)
}//SAVING STUFF DOESNT WORK
//
func SaveApp(){
streakNumberString = String(streakNumber)
defaults.set(streakNumberString, forKey: "streakNumbers")
print("Saved" + String(defaults.integer(forKey: "streakNumbers")))
}
func LoadApp(){
streakNumberString = defaults.string(forKey: "streakNumbers")!
print (defaults.integer(forKey: "streakNumbers") )
streakNumber = Int(streakNumberString)!
streakNumberLabel.text = String(streakNumber)
}//
}
最佳答案
错误说明了一切。您无法在 ViewController
上调用 SaveApp()
。您实际上需要一个 ViewController
实例来调用 SaveApp()
本身。
如果您希望 ViewController
实例在应用程序终止时保存其数据,您可以从 AppDelegate
的 applicationDidEnterBackground
方法发布通知,每当应用程序最小化时以及终止之前都会调用它:
func applicationDidEnterBackground(_ application: UIApplication) {
NotificationCenter.default.post(Notification(name: Notification.Name("AppAboutToTerminateOrMinimize")))
}
然后您可以在 ViewController
的 viewDidLoad()
中订阅该通知:
NotificationCenter.default.addObserver(self,
selector: #selector(AppSave),
name: Notification.Name("AppAboutToTerminateOrMinimize"),
object: nil)
或者正如rmaddy在评论中提到的,您可以将以下代码放入ViewController
的viewDidLoad()
中并跳过AppDelegate
部分:
NotificationCenter.default.addObserver(self,
selector: #selector(AppSave),
name: Notification(name: UIApplicationDidEnterBackgroundNotification,
object: nil)
这样,当应用程序最小化/终止时,AppDelegate
将发送通知,ViewController
实例(如果处于事件状态)将接收它并调用 AppSave()
您必须将 AppSave()
方法注释为 @objc
最好使用小驼峰命名法来命名属性和方法/即 appSave()
而不是 AppSave()
关于ios - 让应用程序在终止时保存数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/46894471/