我正在尝试使我的选择器视图的第一行无法选择，但它不起作用。我已经尝试了以下选项，但是两个都给出了一些错误或用于以前的swift版本。
- 禁用Uipickerview中的特定行值
- (ios(如何在Uipickerview中获得第一个值？
我的代码：
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
if (pickerView.tag == 1){
return list1.count
} else {
return list2.count
}
}
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
if (pickerView.tag == 1){
return "(list1[row])"
} else {
return "(list2[row])"
}
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
if pickerView.tag == 1 {
frequency = list1[row]
} else {
period = list2[row]
}
}
我的数组：
list1 = ["Select", "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"]
list2 = ["Select", "days", "weeks"]
我想在两个Pickerviews中使"选择"不可选择。另外，如果用户不更改pickerview选项(即使选择"选择"(，我也想发送一个错误，即使它是不可选择的(。
按钮代码继续：
@IBAction func addActivity(_ sender: Any) {
if (input.text != "" && pickerString != "Select") {
nameActivity = input.text!
list.append(nameActivity)
input.text = ""
} else if (input.text == "") {
let alertController = UIAlertController(title: "Error", message:
"Please give the activity a name!", preferredStyle: UIAlertControllerStyle.alert)
alertController.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.default,handler: nil))
self.present(alertController, animated: true, completion: nil)
} else if pickerString == "Select" {
let alertController = UIAlertController(title: "Error", message:
"Select something", preferredStyle: UIAlertControllerStyle.alert)
alertController.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.default,handler: nil))
}
}
我相信，在您的情况下以下将有效：
override open func viewDidLoad() {
super.viewDidLoad()
// Set the initial selection of both picker views to the first item, this will prevent the user from proceeding without changing the selections.
frequencyPicker.selectRow(0, inComponent: 0, animated: false)
periodPicker.selectRow(0, inComponent: 0, animated: false)
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
var selectedRow = row
if selectedRow == 0 {
selectedRow = 1
pickerView.selectRow(selectedRow, inComponent: component, animated: false)
}
if pickerView.tag == 1 {
frequency = list1[selectedRow]
} else {
period = list2[selectedRow]
}
}
在您的继续行动中，您可以实施这样的事情：
func continue() {
if frequencyPicker.selectedRow(inComponent: 0) == 0 || periodPicker.selectedRow(inComponent: 0) == 0 {
// Alert the user that he needs to pick the correct values.
return
}
// Perform some action to proceed in the application.
}
您可以做一件事。让您的第一个元素为" - 选择 - - "。现在创建一个类型的变量，将Picker视图行值存储在此字符串中。如果所选的行等于" - 选择 - - "，则创建一个警报并通知用户选择您的选项。
或
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
// Check row
print(row)
if(row == 0)
{
//Create an alert
}
else
{
// IMPLEMENT_CODE
}
}
更新1：
class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate
{
@IBOutlet var pickerView: [UIPickerView]!
var pickerString:String = "--Select--"
var array:[String] = ["--Select--","Apple","Ball","Cat","Dog"]
// number of rows or number of components
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
// number of rows that we have to set
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return array.count
}
// set title in picker view according to the elements
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return array[row]
}
// when an element is selected, store in a string
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
print(row)
pickerString = array[row]
print(pickerString)
}
在此处，当您在Pickerview中选择任何行时，字符串存储在字符串中，您还可以看到选择的行号。
您还可以添加一个按钮，以便如果字符串具有" - 选择 - "，则在按钮操作中，它将显示一个警报。或者将行值存储在整数变量和按钮操作中，如果整数变量== 0，则创建一个警报。
更新2：
@IBAction func addActivity(_ sender: Any) {
if (input.text == "") {
let alertController = UIAlertController(title: "Error", message:
"Please give the activity a name!",preferredStyle:UIAlertControllerStyle.alert)
alertController.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.default,handler: nil))
self.present(alertController, animated: true, completion: nil)
}
else
if pickerString == "Select" {
let alertController = UIAlertController(title: "Error", message:
"Select something", preferredStyle: UIAlertControllerStyle.alert)
alertController.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.default,handler: nil))
}
else
{
nameActivity = input.text!
list.append(nameActivity)
input.text = ""
}
}
更新3：
class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate, UITextFieldDelegate, UITextViewDelegate {
@IBOutlet var pickerView: [UIPickerView]!
@IBOutlet var selectAny: UILabel!
var pickerString:String = “—-Select-—“
var array:[String] = ["—-Select-—“,”Apple”,”Ball”,”Cat”,”Dog”]
// number of rows or number of components
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
// number of rows that we have to set
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return array.count
}
// set title in picker view according to the elements
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return array[row]
}
// when an element is selected, store in a string
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
print(row)
pickerString = array[row]
print(pickerString)
}
// Button action
@IBAction func buttonAction(_ sender: UIButton) {
print(pickerString)
print(length!)
if(pickerString == “--Select--“){
let alert = UIAlertController(title: “Error”, message: "Please select.”, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)
}
else
if(pickerString != “—-Select—-“){
yourCode()
}
}
func yourCode()
{
// do whatever you want
}
}