ios - 弹出菜单继续

Question

我正在 Xcode 8.2.1 上的 Swift 中制作一个弹出菜单，但我不知道如何使其正确连接(它现在正在以编程方式创建，以便当您打开它时它会有一个动画)。

import UIKit

var clickj = false
var st = String()

class ViewController: UIViewController {

    var button = dropDownBtn()

    override func viewDidLoad() {
        super.viewDidLoad()

        if clickj == true {
            performSegue(withIdentifier: st, sender: nil)
        }

        // Do any additional setup after loading the view, typically from a nib.


        //Configure the button
        button = dropDownBtn.init(frame: CGRect(x: 0, y: 0, width: 0, height: 0))
        button.setTitle("Colors", for: .normal)
        button.translatesAutoresizingMaskIntoConstraints = false

        //Add Button to the View Controller
        self.view.addSubview(button)

        //button Constraints
        button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
        button.widthAnchor.constraint(equalToConstant: 100).isActive = true
        button.heightAnchor.constraint(equalToConstant: 40).isActive = true

        //Set the drop down menu's options
        button.dropView.dropDownOptions = ["Blue", "Choices"]

        }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

protocol dropDownProtocol {
    func dropDownPressed(string : String)
}

class dropDownBtn: UIButton, dropDownProtocol {

    func dropDownPressed(string: String) {
        print(string)
        st = string
        clickj = true
        self.dismissDropDown()
    }

    var dropView = dropDownView()

    var height = NSLayoutConstraint()


    override init(frame: CGRect) {
        super.init(frame: frame)

        self.backgroundColor = UIColor.darkGray

        dropView = dropDownView.init(frame: CGRect.init(x: 0, y: 0, width: 0, height: 0))
        dropView.delegate = self
        dropView.translatesAutoresizingMaskIntoConstraints = false
    }

    override func didMoveToSuperview() {
        self.superview?.addSubview(dropView)
        self.superview?.bringSubview(toFront: dropView)
        dropView.topAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
        dropView.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
        dropView.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
        height = dropView.heightAnchor.constraint(equalToConstant: 0)
    }

    var isOpen = false
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        if isOpen == false {

            isOpen = true

            NSLayoutConstraint.deactivate([self.height])

            if self.dropView.tableView.contentSize.height > 150 {
                self.height.constant = 150
            } else {
                self.height.constant = self.dropView.tableView.contentSize.height
            }


            NSLayoutConstraint.activate([self.height])

            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
                self.dropView.layoutIfNeeded()
                self.dropView.center.y += self.dropView.frame.height / 2
            }, completion: nil)

        } else {
            isOpen = false

            NSLayoutConstraint.deactivate([self.height])
            self.height.constant = 0
            NSLayoutConstraint.activate([self.height])
            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
                self.dropView.center.y -= self.dropView.frame.height / 2
                self.dropView.layoutIfNeeded()
            }, completion: nil)

        }
    }

    func dismissDropDown() {
        isOpen = false
        NSLayoutConstraint.deactivate([self.height])
        self.height.constant = 0
        NSLayoutConstraint.activate([self.height])
        UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
            self.dropView.center.y -= self.dropView.frame.height / 2
            self.dropView.layoutIfNeeded()
        }, completion: nil)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

class dropDownView: UIView, UITableViewDelegate, UITableViewDataSource  {

    var dropDownOptions = [String]()

    var tableView = UITableView()

    var delegate : dropDownProtocol!

    override init(frame: CGRect) {
        super.init(frame: frame)

        tableView.backgroundColor = UIColor.darkGray
        self.backgroundColor = UIColor.darkGray


        tableView.delegate = self
        tableView.dataSource = self

        tableView.translatesAutoresizingMaskIntoConstraints = false

        self.addSubview(tableView)

        tableView.leftAnchor.constraint(equalTo: self.leftAnchor).isActive = true
        tableView.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
        tableView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
        tableView.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true

    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return dropDownOptions.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = UITableViewCell()

        cell.textLabel?.text = dropDownOptions[indexPath.row]
        cell.backgroundColor = UIColor.darkGray
        return cell
    }

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        self.delegate.dropDownPressed(string: dropDownOptions[indexPath.row])
        self.tableView.deselectRow(at: indexPath, animated: true)
    }

}

问题是我已经将所有内容都设置为正确的segue，但我仍在研究应该在哪里放置 if 语句，该语句将在条件为真时进行segue(主要是我正在寻找一些可以将其放置在其中的函数)单击按钮时将在主 ViewController 中调用)。

Answer 1

你已经很接近了......你所需要的只是实现另一个委托(delegate)协议(protocol)。

目前，您的 dropDownView 正在使用 dropDownProtocol 告诉按钮已选择一行。您还需要一个协议(protocol)，以便按钮可以告诉 View Controller 它已自行退出，并从表中传递选定的字符串。

这是您提供的代码，几乎没有进行任何更改。请参阅代码中的注释。开始后，事情应该非常清楚 - 如果需要，请随时要求澄清:

import UIKit

class ViewController: UIViewController,  dropDownCallBackProtocol {

    var button = dropDownBtn()

    override func viewDidLoad() {
        super.viewDidLoad()

        //Configure the button
        button = dropDownBtn.init(frame: CGRect(x: 0, y: 0, width: 0, height: 0))
        button.setTitle("Colors", for: .normal)
        button.translatesAutoresizingMaskIntoConstraints = false

        //Add Button to the View Controller
        self.view.addSubview(button)

        //button Constraints
        button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
        button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
        button.widthAnchor.constraint(equalToConstant: 100).isActive = true
        button.heightAnchor.constraint(equalToConstant: 40).isActive = true

        //Set the drop down menu's options
        button.dropView.dropDownOptions = ["Blue", "Choices"]

        // set the button's "vcCallBackDelegate"
        button.vcCallBackDelegate = self

    }

    func dropDownCompleted(string: String) {
        print("Inside View Controller:", string)
        // this will be called when the un-show-drop-down animation is finished
        // so you can perform your segue here
        // performSegue(withIdentifier: string, sender: nil)
    }

}

// protocol for the button to "call back" to the view controller (its parent)
protocol dropDownCallBackProtocol {
    func dropDownCompleted(string : String)
}

// protocol for the table to "call back" to the button (its parent)
protocol dropDownProtocol {
    func dropDownPressed(string : String)
}

class dropDownBtn: UIButton, dropDownProtocol {

    var vcCallBackDelegate: dropDownCallBackProtocol?

    func dropDownPressed(string: String) {
        print("Inside button class:", string)
        self.dismissDropDown(string)
    }

    var dropView = dropDownView()

    var height = NSLayoutConstraint()

    override init(frame: CGRect) {
        super.init(frame: frame)

        self.backgroundColor = UIColor.darkGray

        dropView = dropDownView.init(frame: CGRect.init(x: 0, y: 0, width: 0, height: 0))
        dropView.delegate = self
        dropView.translatesAutoresizingMaskIntoConstraints = false
    }

    override func didMoveToSuperview() {
        self.superview?.addSubview(dropView)
        self.superview?.bringSubview(toFront: dropView)
        dropView.topAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
        dropView.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
        dropView.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
        height = dropView.heightAnchor.constraint(equalToConstant: 0)
    }

    var isOpen = false
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        if isOpen == false {
            isOpen = true
            NSLayoutConstraint.deactivate([self.height])
            if self.dropView.tableView.contentSize.height > 150 {
                self.height.constant = 150
            } else {
                self.height.constant = self.dropView.tableView.contentSize.height
            }
            NSLayoutConstraint.activate([self.height])
            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
                self.dropView.layoutIfNeeded()
                self.dropView.center.y += self.dropView.frame.height / 2
            }, completion: nil)
        } else {
            isOpen = false

            NSLayoutConstraint.deactivate([self.height])
            self.height.constant = 0
            NSLayoutConstraint.activate([self.height])
            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
                self.dropView.center.y -= self.dropView.frame.height / 2
                self.dropView.layoutIfNeeded()
            }, completion: nil)

        }
    }

    func dismissDropDown(_ selectedString: String) {
        isOpen = false
        NSLayoutConstraint.deactivate([self.height])
        self.height.constant = 0
        NSLayoutConstraint.activate([self.height])
        UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
            self.dropView.center.y -= self.dropView.frame.height / 2
            self.dropView.layoutIfNeeded()
        }, completion: {
            b in
            // tell the delegate the animation is complete, and pass the selected string
            self.vcCallBackDelegate?.dropDownCompleted(string: selectedString)
        })
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

class dropDownView: UIView, UITableViewDelegate, UITableViewDataSource  {

    var dropDownOptions = [String]()

    var tableView = UITableView()

    var delegate : dropDownProtocol!

    override init(frame: CGRect) {
        super.init(frame: frame)

        tableView.backgroundColor = UIColor.darkGray
        self.backgroundColor = UIColor.darkGray


        tableView.delegate = self
        tableView.dataSource = self

        tableView.translatesAutoresizingMaskIntoConstraints = false

        self.addSubview(tableView)

        tableView.leftAnchor.constraint(equalTo: self.leftAnchor).isActive = true
        tableView.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
        tableView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
        tableView.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true

    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return dropDownOptions.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = UITableViewCell()

        cell.textLabel?.text = dropDownOptions[indexPath.row]
        cell.backgroundColor = UIColor.darkGray
        return cell
    }

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        self.delegate.dropDownPressed(string: dropDownOptions[indexPath.row])
        self.tableView.deselectRow(at: indexPath, animated: true)
    }

}