Question

如何使用元组数组加载UIPickerView？

使用以下代码，我只在UIPickerView中看到Oregon: 9.0。

let myArrayTuple: [(String, Double)] = [("Illinois", 7.0), ("Wisconsin", 8.0), ("Oregon" ,9.0)]

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {    
    var stateName:String?
    var stateTax:Double?

    for (name , tax) in myArrayTuple{
         stateName = name
         stateTax = tax
    }
    return stateName! +  ": \(stateTax!)"
}

编辑：您就是这样做的：请参阅Shadow Of

的回答

在下面的示例中，我使用的是命名元组，而不是Shadow Of示例中的默认值。

let myArrayTuple: [(name:String, tax:Double)] = [("Illinois", 7.0), ("Wisconsin", 8.0), ("Oregon" ,9.0)]

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

    let stateName = myArrayTuple[row]
    return stateName.name +  ": \(stateName.tax)"
}

Answer 1

这就是你应该如何使用UIPickerView，我想：

func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return myArrayTuple.count
}

func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    let current = myArrayTuple[row]
    return current.0 + ": \(current.1)"
}

Answer 2

您遇到与for loop理解相关的问题。

 for (name , tax) in myArrayTuple{
      stateName = name
      stateTax = tax
 }

你从0元素到2，在每次迭代中你设置新的值并且不返回它。

在循环结束后，您只能看到最后一个元素的最后一个值＆＃39;案例2。

来自阵列元组的UIPicker

2 个答案: