我的代码存在这个问题，我的PageViewController有一个函数，它根据用户正在查看的视图在导航栏上显示视图控制器的标题。但是，当我运行应用程序时，它开始没有标题，并且该功能仅在用户开始滚动页面时实现。我想知道我能做些什么来解决这个问题吗？我使用的函数包括一个switch语句，可以在下面和下面的整个类代码中看到：
func pageViewController(pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
if (!completed) {
return
}
if let firstViewController = viewControllers?.first,
let arrayIndex = orderedViewControllers.indexOf(firstViewController) {
switch arrayIndex {
case 0:
self.navigationController!.navigationBar.topItem!.title = "Monday"
break
case 1:
self.navigationController!.navigationBar.topItem!.title = "Tuesday"
break
case 2:
self.navigationController!.navigationBar.topItem!.title = "Wednesday"
break
case 3:
self.navigationController!.navigationBar.topItem!.title = "Thursday"
case 4:
self.navigationController!.navigationBar.topItem!.title = "Friday"
break
case 5:
self.navigationController!.navigationBar.topItem!.title = "Saturday"
break
case 6:
self.navigationController!.navigationBar.topItem!.title = "Sunday"
break
default:
self.navigationController!.navigationBar.topItem!.title = "Timetable"
}
}
}
代码：（PageViewController.swift）
import UIKit
import ChameleonFramework
class PageViewController: UIPageViewController,UIPageViewControllerDelegate {
// created for use in the function which determines the title of the navigationBar
var arrayIndex: Int = 0
// reference for later function to determine title of navigationBar
var pageControl = UIPageControl.self
// NSUserDefaults
let defaults = NSUserDefaults.standardUserDefaults()
// set of viewControllers (based on their storyboard ID)
private(set) lazy var orderedViewControllers: [UIViewController] = {
return [self.newDayViewController("monday"),
self.newDayViewController("tuesday"),
self.newDayViewController("wednesday"),
self.newDayViewController("thursday"),
self.newDayViewController("friday"),
self.newDayViewController("saturday"),
self.newDayViewController("sunday")
]
}()
override func viewDidLoad() {
super.viewDidLoad()
self.setNeedsStatusBarAppearanceUpdate()
// setting the datasource & Delegate of the UIPageViewController
dataSource = self
delegate = self
// set the first viewController for the pageView (monday as it is the first in the set)
if let firstViewController = orderedViewControllers.first {
setViewControllers([firstViewController],
direction: .Forward,
animated: true,
completion: nil)
}
}
// function to add view controllers
// function will only instantiateViewControllers which have a storyboard id containing 'day' e.g Monday, Tuesday, Wednesday
private func newDayViewController(day: String) -> UIViewController {
return UIStoryboard(name: "Main", bundle: nil) .
instantiateViewControllerWithIdentifier("\(day)")
}
// set the navigationBar title to the dayViewController's title
// if the user is looking at orderedViewControllers[1], then the title of that day is "Tuesday"
func pageViewController(pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
if (!completed) {
return
}
if let firstViewController = viewControllers?.first,
let arrayIndex = orderedViewControllers.indexOf(firstViewController) {
switch arrayIndex {
case 0:
self.navigationController!.navigationBar.topItem!.title = "Monday"
break
case 1:
self.navigationController!.navigationBar.topItem!.title = "Tuesday"
break
case 2:
self.navigationController!.navigationBar.topItem!.title = "Wednesday"
break
case 3:
self.navigationController!.navigationBar.topItem!.title = "Thursday"
case 4:
self.navigationController!.navigationBar.topItem!.title = "Friday"
break
case 5:
self.navigationController!.navigationBar.topItem!.title = "Saturday"
break
case 6:
self.navigationController!.navigationBar.topItem!.title = "Sunday"
break
default:
self.navigationController!.navigationBar.topItem!.title = "Timetable"
}
}
}
}
// Mandatory functions and setup for the pageViewController to work
extension PageViewController: UIPageViewControllerDataSource {
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 orderedViewControllers.last
}
guard orderedViewControllers.count > previousIndex else {
return nil
}
return orderedViewControllers[previousIndex]
}
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 orderedViewControllers.first
}
guard orderedViewControllersCount > nextIndex else {
return nil
}
return orderedViewControllers[nextIndex]
}
// set number of viewControllers to be presented
func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
return orderedViewControllers.count
}
func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
guard let firstViewController = viewControllers?.first,
firstViewControllerIndex = orderedViewControllers.indexOf(firstViewController) else {
return 0
}
return firstViewControllerIndex
}
}
答案 0 :(得分：4)
在viewDidLoad()方法中添加
self.navigationItem.title
或
self.title
答案 1 :(得分：3)
使用此代码它适合您
override func viewDidLoad()
{
self.title="your title"
或者
self.navigationItem.title = "YourTitle"