将按钮添加到 UIPickerView 以转到下一个数字
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【中文标题】将按钮添加到 UIPickerView 以转到下一个数字【英文标题】：Add button to UIPickerView to go to next number 【发布时间】：2017-09-12 18:15:23 【问题描述】：我的pickerView 上有 3 列，它代表一个 3 位数字。有什么我可以添加到UIButton 的功能来使***转动吗？例如，当它显示“119”时，按下UIButton，它应该转到“120”。到目前为止，这是我所拥有的：
class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate
@IBOutlet weak var label: UILabel!
@IBOutlet weak var pickerView: UIPickerView!
let numbers = ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"]
func numberOfComponents(in pickerView: UIPickerView) -> Int
return 3
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String?
return numbers[row]
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
return numbers.count
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int)
let val1 = numbers[pickerView.selectedRow(inComponent: 0)]
let val2 = numbers[pickerView.selectedRow(inComponent: 1)]
let val3 = numbers[pickerView.selectedRow(inComponent: 2)]
label.text = "\(val1) \(val2) \(val3)"
【问题讨论】：
【参考方案1】：这是您的简化代码。 buttonPressed 将导致 pickerView 转到下一个号码。当它到达 999 时，它又回到 000。
class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate
@IBOutlet weak var label: UILabel!
@IBOutlet weak var pickerView: UIPickerView!
override func viewDidLoad()
super.viewDidLoad()
changeLabelText()
func numberOfComponents(in pickerView: UIPickerView) -> Int
return 3
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String?
return "\(row)"
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
return 10
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int)
changeLabelText()
fileprivate func num(_ i: Int) -> Int
return pickerView.selectedRow(inComponent: i)
@IBAction func buttonPressed()
let currentNum = num(0) * 100 + num(1) * 10 + num(2)
let nextNum = currentNum + 1
pickerView.selectRow(nextNum % 1000 / 100, inComponent: 0, animated: true)
pickerView.selectRow(nextNum % 100 / 10, inComponent: 1, animated: true)
pickerView.selectRow(nextNum % 10, inComponent: 2, animated: true)
changeLabelText()
fileprivate func changeLabelText()
label.text = "\(num(0)) \(num(1)) \(num(2))"
【讨论】：
【参考方案2】：当然，使用selectRow 方法，它将选择特定列（又名组件）的一行。该方法还可以选择对此更改进行动画处理。向情节提要添加一个按钮并将其连接到如下方法：
@IBAction func go120(_ sender: Any)
pickerView.selectRow(1, inComponent: 0, animated: true)
pickerView.selectRow(2, inComponent: 1, animated: true)
pickerView.selectRow(0, inComponent: 2, animated: true)
【讨论】：
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