UIPickerView是一个简易的列表控件，用于提供有限个数的选项供用户选择。
它是通过代理和数据源的方法对其进行设置和数据源填充的，这种控件的设计模式也是代理模式的应用之一。
添加下面的代码即可实现基本功能。
class ViewController: UIViewController,UIPickerViewDelegate,UIPickerViewDataSource {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let picker = UIPickerView(frame:CGRect(x:20, y:100, width:500, height:150))
picker.delegate = self
picker.dataSource = self
self.view.addSubview(picker)
}
//设置视图的分区数，也可以理解为选择列表的列数
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 2
}
//设置每个分区的行数，参数component用于判断具体的分区
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return 8
}
//返回设置列表中每一行的数据，参数row和component分别用于区分行和列
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return "\(component)area\(row)line data"
}
//返回值设置具体行的行高
func pickerView(_ pickerView: UIPickerView, rowHeightForComponent component: Int) -> CGFloat {
return 50
}
//返回值设置分区的宽度，即列的宽度
func pickerView(_ pickerView: UIPickerView, widthForComponent component: Int) -> CGFloat {
return 200
}
//选中数据时的回调代理
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
print("\(component)area\(row)line data")
}