如何向页面控制器添加按钮

Question

我想知道如何添加按钮(左和右)来更改页面控制视图。我正在编写这个教程1：http://www.edumobile.org/iphone/iphone-programming-tutorials/pagecontrol-example-in-iphone/。除了这个示例代码中的切换功能之外，我如何添加两个简单的按钮(左和右)来翻页？

我是一个程序员初学者，所以任何类型的答案都是非常有用的！:)

谢谢!

Answer 1

您可以向视图中添加两个按钮，当单击该按钮时，可以根据单击的按钮调用一个方法来翻页。

UIButton *leftButton = [[UIButton alloc] init];
leftbutton.frame = leftButtonFrame;
[leftbutton setTitle:@"Left" forState:UIControlStateNormal];
[leftbutton addTarget:self action:@selector(leftbuttonClicked:) forControlEvents:UIControlEventTouchUpInside];
[yourView addSubview:leftbutton];


UIButton *rightButton = [[UIButton alloc] init];
rightButton.frame = rightButtonFrame;
[rightButton setTitle:@"Right" forState:UIControlStateNormal];
[rightButton addTarget:self action:@selector(rightButtonClicked:) forControlEvents:UIControlEventTouchUpInside];
[yourView addSubview:rightButton];

- (void)leftButtonclicked:(id)sender
{
//Code to turn page left
}

- (void)rightButtonclicked:(id)sender
{
//Code to turn page right
}

Answer 2

我会迅速回答这个问题，但你应该会翻译。

这个过程是找到PageControl视图，添加两个按钮，并在适当的时候隐藏按钮(即第一页没有上一个按钮)。

我把按钮放在PageControl的左边和右边。默认行为是触摸那里会后退和前进一页。因此，我将按钮设置为enabled=false，以便触摸执行此默认行为。

首先，我们需要一个枚举来帮助定位按钮。使用视图中其他地方不会使用的值。

enum enumBtnTag: Int {
    case tagPrev = 9991
    case tagNext = 9992

}

var pageNbr = 0  //Needed to keep track of page being displayed

现在我们将在ViewDidLoad中添加按钮。首先我找到PageControl，然后查找按钮，这样就不会创建两次。(ViewDidload可能会被多次调用)

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    for view in self.view.subviews {
        if view is UIPageControl {
            let curr:UIPageControl = view as! UIPageControl
            curr.backgroundColor = UIColor.clear
            curr.currentPageIndicatorTintColor = UIColor.red   //Page Dot is red
            curr.pageIndicatorTintColor = UIColor.black   //Other dots are black

            let pcSz = view.frame
            let btnSz = CGSize(width: 35, height: 50)  //Use your button size


            if let _ = self.view.viewWithTag(enumBtnTag.tagNext.rawValue) as? UIButton {}
            else {   //Next Button not found
                let Nbtn = UIButton(frame: CGRect(x: pcSz.width - btnSz.width, y: -15, width: btnSz.width, height: btnSz.height))
                Nbtn.setTitle(">>", for: UIControlState.normal)
                Nbtn.backgroundColor = UIColor.clear
                Nbtn.setTitleColor(UIColor.brown, for: UIControlState.normal)
                Nbtn.titleLabel?.font = UIFont(name: enumFontNames.MarkerFelt_Wide.rawValue, size: 60.0)
                Nbtn.isEnabled = false  //Allows touch to fall through to PageControl
                Nbtn.tag = enumBtnTag.tagNext.rawValue

                view.addSubview(Nbtn)

            }


            if let _ = self.view.viewWithTag(enumBtnTag.tagPrev.rawValue) as? UIButton {}
            else {   //Prev Button not found
                let Pbtn = UIButton(frame: CGRect(x: 0, y: -15, width: btnSz.width, height: btnSz.height))
                Pbtn.setTitle("<<", for: UIControlState.normal)
                Pbtn.backgroundColor = UIColor.clear
                Pbtn.setTitleColor(UIColor.brown, for: UIControlState.normal)
                Pbtn.titleLabel?.font = UIFont(name: enumFontNames.MarkerFelt_Wide.rawValue, size: 60.0)
                Pbtn.isEnabled = false
                Pbtn.isHidden = true
                Pbtn.tag = enumBtnTag.tagPrev.rawValue

                view.addSubview(Pbtn)
            }
        }
    }

}

然后，我捕获将要显示的页面。页面可能不会显示(用户拖动的距离不够远)，但这会在以后处理。

func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {

    if let identifier = pendingViewControllers[0].restorationIdentifier {
        if let index = pages.index(of: identifier) {
            pageNbr = index
        }
    }

}

现在我们在didFinishAnimating中修改按钮；

func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {

    if finished && completed {

        if let button = self.view.viewWithTag(enumBtnTag.tagPrev.rawValue) as? UIButton {
            if pageNbr > 0 {
                button.isHidden = false
            } else {
                button.isHidden = true
            }
        }


        if let button = self.view.viewWithTag(enumBtnTag.tagNext.rawValue) as? UIButton {
            if pageNbr < pages.count - 1 {
               button.isHidden = true
            } else {
               button.isHidden = false
            }
        }

    }

}

奖励代码:我在下一个按钮所在的最后一页添加了一个保存功能。您需要设置按钮已启用(以便它注册触摸)并设置目标(您想要执行的任何函数)；我的是"nextSegue“。当然，当不在最后一页时，删除目标；

if pageNbr < pages.count - 1 {
    //Not on last page. Use next button
    button.setTitle(">>", for: UIControlState.normal)
    button.removeTarget(self, action:  #selector(nextSegue), for: UIControlEvents.touchUpInside)
    button.isEnabled = false
} else {
    //On last page. Use save button
    button.setTitle("S", for: UIControlState.normal)
    button.addTarget(self, action: #selector(nextSegue), for: UIControlEvents.touchUpInside)
    button.isEnabled = true
}

希望这对某些人有帮助。