Swift Delegate 函数未执行

Question

我有一个包含三个 ViewController 的 UIPageViewcontroller。一个 Viewcontroller 是我的 ProfileViewcontroller。我的 ProfileViewController 中有一个按钮，按下时应该告诉 UIPageViewController 切换到下一个 Viewcontroller。 这是我第一次实现委托，但我无法弄清楚为什么它不起作用。

UIPageViewController 类：

class PageViewController: UIPageViewController, ProfileViewControllerDelegate {

private(set) lazy var orderedViewControllers: [UIViewController] = {


// The view controllers will be shown in this order
return [self.newColoredViewController("Search"),
      self.newColoredViewController("Menu"),
      self.newColoredViewController("Profile"),
      self.newColoredViewController("Offer")]
}()

override func viewDidLoad() {
super.viewDidLoad()

dataSource = self



if orderedViewControllers.count >= 2 {
scrollToViewController(orderedViewControllers[1])
}

}

// MARK: ProfileViewControllerDelegate
func profileViewControllerDidTouchOffer(viewController:ProfileViewController, sender: AnyObject) {
scrollToNextViewController()
print("I'm pressing the offer Button")
}

ProfileViewController 类：

protocol ProfileViewControllerDelegate : class {
func profileViewControllerDidTouchOffer(controller:   ProfileViewController, sender: AnyObject)
}

class ProfileViewController: UIViewController {

weak var delegate: ProfileViewControllerDelegate?

@IBOutlet var profileImageView: SpringImageView!
@IBOutlet var offerButton: UIButton!

override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
@IBAction func offerButtonTouchUpInside(sender: AnyObject) {

delegate?.profileViewControllerDidTouchOffer(self, sender: sender)

}

回答

我通过更改在 orderderedViewControllers 中添加 ViewControllers 的方式更新了 PageViewController 类：

private(set) lazy var orderedViewControllers: [UIViewController] = {
// The view controllers will be shown in this order

let profileVC = UIStoryboard(name: "Main", bundle: nil)   .instantiateViewControllerWithIdentifier("ProfileViewController") as!   ProfileViewController
profileVC.delegate = self

return [self.newColoredViewController("Search"),
      self.newColoredViewController("Menu"),
      profileVC,
      self.newColoredViewController("Offer")]
}()

Answer 1

看起来您正在使用 InterfaceBuilder，所以我不确定它是如何在那里完成的（可能在 prepareForSegue 中），但典型的模式是这样的：

let vc = ProfileViewController() 
vc.delegate = self // Or whatever you want to act as the delegate 
// Now show the view controller. 

关键是在使用视图控制器之前，你要确保它的委托属性被设置为委托并且符合协议。通常，调用控制器将是委托。

编辑：如果您使用的是 UIPageViewController，那么您应该将委托添加到 viewController，然后再将其传递给 setViewControllers https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIPageViewControllerClassReferenceClassRef/#//apple_ref/occ/instm/UIPageViewController/setViewControllers:direction:animated:completion：