Question

＆＃34;已经回答了类似的问题，但是我的应用程序无效＃34;

有什么方法可以让我的UIPickerView轮作为循环？我在每一列上都有0到9但我不希望它在9结束。我还有一个UIButton，它有一个func，这使得数字跳过一个数字并从它开始000到999，如果我将UIPickerView作为循环，我不希望它对其数学顺序做出任何更改或影响这就是我到目前为止所拥有的：

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)"
}

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))"
}

根据已经回答的其他问题，我必须编辑我的代码，如：

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

func valueForRow(row: Int) -> Int {
    // the rows repeat every `pickerViewData.count` items
    return pickerViewData[row % pickerViewData.count]
}

func rowForValue(value: Int) -> Int? {
    if let valueIndex = find(pickerViewData, value) {
        return pickerViewMiddle + value
    }
    return nil
}

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
    return "\(valueForRow(row))"
}

func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
    return 3
}

func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return pickerViewRows
}

// whenever the picker view comes to rest, we'll jump back to
// the row with the current value that is closest to the middle
func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    let newRow = pickerViewMiddle + (row % pickerViewData.count)
    pickerView.selectRow(newRow, inComponent: 0, animated: false)
}



@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)"
}

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))"
}


private let pickerViewData = Array(0...59)     // contents will be 0, 1, 2, 3...59, change to whatever you want
private let pickerViewRows = 10_000            // any big number
private let pickerViewMiddle = ((pickerViewRows / pickerViewData.count) / 2) * pickerViewData.count






override func viewDidLoad() {
    super.viewDidLoad()
    self.picker.delegate = self
    self.picker.dataSource = self
    let initialValue = 0
    if let row = rowForValue(initialValue) {
        self.picker.selectRow(row, inComponent: 0, animated: false)
    }
    // or if you just want to start in the middle:
    // self.picker.selectRow(pickerViewMiddle, inComponent: 0, animated: false)
}

但我在这6个不同的行上得到6个错误：

 if let valueIndex = find(pickerViewData, value) {
        return pickerViewMiddle + value
//
return "\(valueForRow(row))"
//
 private let pickerViewMiddle = ((pickerViewRows / pickerViewData.count) / 2) * pickerViewData.count

//
self.picker.delegate = self
    self.picker.dataSource = self
    let initialValue = 0
    if let row = rowForValue(initialValue) {
        self.picker.selectRow(row, inComponent: 0, animated: false)

Answer 1

这不是无限循环，但应该可以很好地工作。我们的想法是，您将数据源范围增加了想要添加的任何边距的倍数（我只是将边距随机设置为40），当滚动停止时，重新恢复到数据源范围的中间位置。除非用户滚动（40/2 x 10）项而不停止滚动，否则此实现将像无限循环一样工作。添加了显示想法的代码。

let loopingMargin: Int = 40

var data: [String] = ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"]

var picker: UIPickerView  = UIPickerView()

override func viewDidLoad() {
    super.viewDidLoad()

    picker.delegate = self
    picker.dataSource = self
    view.addSubview(picker)
    picker.selectRow((loopingMargin / 2) * data.count, inComponent: 0, animated: false)
}


// MARK: UIPickerViewDelegate, UIPickerViewDataSource
func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return loopingMargin * data.count
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return data[row % data.count]
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    let currentIndex = row % data.count
    picker.selectRow((loopingMargin / 2) * data.count + currentIndex, inComponent: 0, animated: false)
}

Swift：将UIPickerView作为循环进行循环

1 个答案: