iOS App初次启动时的用户引导页制作实例分享

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

    // 得到当前应用的版本号
    let infoDictionary = NSBundle.mainBundle().infoDictionary
    let currentAppVersion = infoDictionary!["CFBundleShortVersionString"] as! String

    // 取出之前保存的版本号
    let userDefaults = NSUserDefaults.standardUserDefaults()
    let appVersion = userDefaults.stringForKey("appVersion")

    let storyboard = UIStoryboard(name: "Main", bundle: nil)

    // 如果 appVersion 为 nil 说明是第一次启动；如果 appVersion 不等于 currentAppVersion 说明是更新了
    if appVersion == nil || appVersion != currentAppVersion {
        // 保存最新的版本号
        userDefaults.setValue(currentAppVersion, forKey: "appVersion")

        let guideViewController = storyboard.instantiateViewControllerWithIdentifier("GuideViewController") as! GuideViewController
        self.window?.rootViewController = guideViewController
    }

    return true
}

class GuideViewController: UIViewController {

    @IBOutlet weak var pageControl: UIPageControl!
    @IBOutlet weak var startButton: UIButton!

    private var scrollView: UIScrollView!

    private let numOfPages = 3

    override func viewDidLoad() {
        super.viewDidLoad()

        let frame = self.view.bounds

        scrollView = UIScrollView(frame: frame)
        scrollView.pagingEnabled = true
        scrollView.showsHorizontalScrollIndicator = false
        scrollView.showsVerticalScrollIndicator = false
        scrollView.scrollsToTop = false
        scrollView.bounces = false
        scrollView.contentOffset = CGPointZero
        // 将 scrollView 的 contentSize 设为屏幕宽度的3倍(根据实际情况改变)
        scrollView.contentSize = CGSize(width: frame.size.width * CGFloat(numOfPages), height: frame.size.height)

        scrollView.delegate = self

        for index  in 0..<numOfPages {
            // 这里注意图片的命名
            let imageView = UIImageView(image: UIImage(named: "GuideImage\(index + 1)"))
            imageView.frame = CGRect(x: frame.size.width * CGFloat(index), y: 0, width: frame.size.width, height: frame.size.height)
            scrollView.addSubview(imageView)
        }

        self.view.insertSubview(scrollView, atIndex: 0)

        // 给开始按钮设置圆角
        startButton.layer.cornerRadius = 15.0
        // 隐藏开始按钮
        startButton.alpha = 0.0
    }

    // 隐藏状态栏
    override func prefersStatusBarHidden() -> Bool {
        return true
    }
}

// MARK: - UIScrollViewDelegate
extension GuideViewController: UIScrollViewDelegate {
    func scrollViewDidScroll(scrollView: UIScrollView) {
        let offset = scrollView.contentOffset
        // 随着滑动改变pageControl的状态
        pageControl.currentPage = Int(offset.x / view.bounds.width)

        // 因为currentPage是从0开始，所以numOfPages减1
        if pageControl.currentPage == numOfPages - 1 {
            UIView.animateWithDuration(0.5) {
                self.startButton.alpha = 1.0
            }
        } else {
            UIView.animateWithDuration(0.2) {
                self.startButton.alpha = 0.0
            }
        }
    }
}