使用swift制作下拉列表？

Question

在swift中制作下拉菜单的库是什么？我是Xcode和Swift语言的新手,所以有人可以指导我如何在swift中实现下拉列表吗？

Answer 1

(Swift 3)将文本框和uipickerview添加到故事板,然后将委托和数据源添加到uipickerview并将委托添加到文本框.关注视频以获取帮助 https://youtu.be/SfjZwgxlwcc

import UIKit

class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource, UITextFieldDelegate {

    @IBOutlet weak var textBox: UITextField!
    @IBOutlet weak var dropDown: UIPickerView!

    var list = ["1", "2", "3"]

    public func numberOfComponents(in pickerView: UIPickerView) -> Int{
        return 1
    }

    public func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int{

        return list.count
    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {

        self.view.endEditing(true)
        return list[row]
    }

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {

        self.textBox.text = self.list[row]
        self.dropDown.isHidden = true
    }

    func textFieldDidBeginEditing(_ textField: UITextField) {

        if textField == self.textBox {
            self.dropDown.isHidden = false
            //if you don't want the users to se the keyboard type:

            textField.endEditing(true)
        }
    }
}

Answer 2

"下拉菜单"是一个网络控件/术语.在iOS中我们没有这些.你可能会更好看UIPopoverController.查看本教程,了解PopoverControllers的一些见解

http://www.raywenderlich.com/29472/ipad-for-iphone-developers-101-in-ios-6-uipopovercontroller-tutorial

Answer 3

不幸的是,如果你想UIPopoverController在iOS9中申请,你会得到一个弃用的警告.相反,您需要设置所需视图的 UIModalPresentationPopover属性以获得相同的结果.

酥料饼

在水平常规环境中,呈现样式,其中内容以弹出视图显示.背景内容变暗,弹出窗口外的水龙头导致弹出窗口被解除.如果您不想使用tap来关闭popover,可以将一个或多个视图分配给关联的UIPopoverPresentationController对象的passthroughViews属性,您可以从popoverPresentationController属性获取该属性.

在水平紧凑的环境中,此选项与UIModalPresentationFullScreen的行为相同.

适用于iOS 8.0及更高版本.

参考:https://developer.apple.com/documentation/uikit/uiviewcontroller/1621355-modalpresentationstyle

Answer 4

您必须确保使用 UIPickerViewDataSource 和 UIPickerViewDelegate 协议，否则从 swift 3 开始它会抛出 AppDelegate 错误

另请注意语法的变化：

func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int

就是现在：

public func numberOfComponents(in pickerView: UIPickerView) -> Int

以下内容对我有用。

import UIkit

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

    @IBOutlet weak var textBox: UITextField!
    @IBOutlet weak var dropDown: UIPickerView!

    var list = ["1", "2", "3"]

    public func numberOfComponents(in pickerView: UIPickerView) -> Int{
        return 1
    }

    public func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int{

        return list.count
    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {

        self.view.endEditing(true)
        return list[row]
    }

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {

        self.textBox.text = self.list[row]
        self.dropDown.isHidden = true
    }

    func textFieldDidBeginEditing(_ textField: UITextField) {

        if textField == self.textBox {
            self.dropDown.isHidden = false
            //if you don't want the users to se the keyboard type:

            textField.endEditing(true)
        }
    }
}