Swift spinner/picker 未保存或显示整数

Question

我想弄清楚为什么我的微调器不能保存整数。当我运行程序时，问号出现在微调器中，而不是 1、2、3、4 等等，一直到 100。我是 Swift 的新手，这是我的第一次使用 spinner/Picker。我的程序应该计算每加仑英里数，但如果我不能让微调器工作，那将不会发生，哈哈。

这是设置变量和微调器的代码：

class SecondViewController:
UIViewController,UIPickerViewDataSource,UIPickerViewDelegate
{
    var BlopSoundURL =  NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("Blop", ofType: "mp3")!)

    var soundAudioPlayer = AVAudioPlayer()

    var miles = 0.0
    var gallonsUsed = 0.0
    var mpg = 0.0

    // Variables for slider
    var minMiles = 1
    var maxMiles = 1000


    @IBOutlet weak var milesDrivenLabel: UILabel!

    @IBAction func milesDrivenSlider(sender: UISlider)
    {

    }

    @IBOutlet weak var gallonsUsedPicker: UIPickerView!
    let pickerData = [1,2,3,4,5,6,7,8,9,10,11,
                12,13,14,15,16,17,18,19,20,21,
                22,23,24,25,26,27,28,29,30,31,
                32,33,34,35,36,37,38,39,40,41,
                42,43,44,45,46,47,48,49,50,51,
                52,53,54,55,56,57,58,59,60,61,
                62,63,64,65,66,67,68,69,70,71,
                72,73,74,75,76,77,78,79,80,81,
                82,83,84,85,86,87,88,89,90,91,
                92,93,94,95,96,97,98,99,100]

尚无提交按钮的代码，但这是微调器和程序的其余代码：

@IBAction func submitButton(sender: UIButton)
{
    soundAudioPlayer.play()
    let row = gallonsUsedPicker.selectedRowInComponent(0)

}



func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int
{
    return 1
}
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
{
    return pickerData.count
}
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> Int!
{
    return pickerData[row]
}


override func viewDidLoad()
{
    super.viewDidLoad()

    gallonsUsedPicker.dataSource = self
    gallonsUsedPicker.delegate = self

    soundAudioPlayer = AVAudioPlayer(contentsOfURL: BlopSoundURL, error: nil)
    // Do any additional setup after loading the view, typically from a nib.
}   // End of viewDidLoad

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


}   // End of SecondViewController

我真的不确定函数中的代码是做什么的，因为这本书没有很好地解释它。然后，我必须弄清楚如何从微调器中获取数字并将其存储在变量中，以便我可以进行 mpg 计算。我知道如何用滑块来做，但不知道微调器。基本上是一样的吗？我有一种感觉，这会变得很有趣。谢谢，非常感谢您的帮助。

Answer 1

首先，根据 Swift 约定，您应该以小写字母开头命名变量，并使用 URLForResource(withExtension:) 方法找出本地资源的 url：

let blopSoundURL = NSBundle.mainBundle().URLForResource("Blop", withExtension: "mp3")!

其次，选择器值应为字符串：

func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
    return 1
}
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
    return "\(row+1)"
}
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return 100
}

你可以使用

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    // do whatever with row+1  here
}

// or 

@IBAction func submitButton(sender: UIButton) {
    soundAudioPlayer.play()
    let rowValue = gallonsUsedPicker.selectedRowInComponent(0) + 1

}

Swift spinner/picker 未保存或显示整数

Swift spinner/picker isn't holding or showing integers

picker

spinner

ios

swift