现在的演练场景只有一次ios swift
问题描述:
我创建了一个PageViewController并添加了三个视图控制器作为我的应用程序的演练,但我希望它们只显示一次,而且我无法弄清楚如何。现在的演练场景只有一次ios swift
,这里是我的pageViewController代码:
import UIKit
class MyPageViewController: UIPageViewController{
override func viewDidLoad() {
super.viewDidLoad()
dataSource = self
// Do any additional setup after loading the view.
if let firstViewController = orderedViewControllers.first {
setViewControllers([firstViewController],
direction: .Forward,
animated: true,
completion: nil)
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//array for the ordered view controllers
private(set) lazy var orderedViewControllers: [UIViewController] = {
return [self.newColoredViewController("First"),
self.newColoredViewController("Second"),
self.newColoredViewController("Third")]
}()
private func newColoredViewController(color: String) -> UIViewController {
return UIStoryboard(name: "Main", bundle: nil) .
instantiateViewControllerWithIdentifier("\(color)ViewController")
}
}
extension MyPageViewController: UIPageViewControllerDataSource {
//returning index of previous view controller
func pageViewController(pageViewController: UIPageViewController,
viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
return nil
}
let previousIndex = viewControllerIndex - 1
guard previousIndex >= 0 else {
return nil
}
guard orderedViewControllers.count > previousIndex else {
return nil
}
return orderedViewControllers[previousIndex]
}
//returning index of the next view controller
func pageViewController(pageViewController: UIPageViewController,
viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
return nil
}
let nextIndex = viewControllerIndex + 1
let orderedViewControllersCount = orderedViewControllers.count
guard orderedViewControllersCount != nextIndex else {
return nil
}
guard orderedViewControllersCount > nextIndex else {
return nil
}
return orderedViewControllers[nextIndex]
}
}
如何编辑的代码只有一次显示呢?
答
从你说过的话我猜你只希望它显示第一次用户打开应用程序,然后不再出现?
Theres有几种方法可以做到这一点,最简单的方法可能是在NSUserDefaults上设置一个属性,这将记住应用程序启动之间的设置。尝试像这样:
// this should be your initial view controller
let defaults = NSUserDefaults.standardUserDefaults()
override func viewDidLoad() {
super.viewDidLoad()
if !defaults.boolForKey("walkthroughSeen") {
// create page view controller and display
let walkthroughVC = UIStoryboard(name: "Main", bundle: nil).
instantiateViewControllerWithIdentifier("MyPageViewController")
self.presentViewController(walkthroughVC, animated: true)
defaults.setBool(true, forKey: "walkthroughSeen")
}
}
谢谢你,这就是我需要的。 :) –