我无法弄清楚如何更改我的代码以使其在我的三个文本字段填写完毕后启用导航栏中的“完成”按钮。

我目前有三个 UITextField 和一个 UIButtonItem。 habitNameField 和 goalField 都是手动文本字段，frequencyField 是一个 Picker View。

@IBOutlet weak var habitNameField: UITextField!
@IBOutlet weak var goalField: UITextField!
@IBOutlet weak var frequencyField: UITextField!

@IBOutlet weak var doneBarButton: UIBarButtonItem!

当在第一个字段中输入内容时，我还有以下功能。

func textField(habitNameField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let oldHabitNameText: NSString = habitNameField.text!
    let newHabitNameText: NSString = oldHabitNameText.stringByReplacingCharactersInRange(range, withString: string)
    doneBarButton.enabled = (newHabitNameText.length != 0)
    return true
}

我尝试更改代码，使其将其他两个字段作为参数，并仅在所有三个字段都已填写时才启用 doneBarButton。

func textField(habitNameField: UITextField, goalField: UITextField, frequencyField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let habitNameText: NSString = (habitNameField.text!).stringByReplacingCharactersInRange(range, withString: string)
    let goalText: NSString = (goalField.text!).stringByReplacingCharactersInRange(range, withString: string)
    let frequencyText: NSString = (frequencyField.text!).stringByReplacingCharactersInRange(range, withString: string)

    doneBarButton.enabled = (habitNameText.length != 0) && (goalText.length != 0) && (frequencyText.length != 0)
    return true
}

但是，它不起作用，即使我填写了所有三个文本字段也是如此。

我非常感谢任何帮助，并感谢任何提前做出贡献的人!

所有代码在这里:

class HabitDetailViewController: UITableViewController, UITextFieldDelegate, UIPickerViewDataSource,UIPickerViewDelegate {
@IBOutlet weak var habitNameField: UITextField!
@IBOutlet weak var goalField: UITextField!
@IBOutlet weak var doneBarButton: UIBarButtonItem!
@IBOutlet weak var frequencyField: UITextField!

var frequencies = ["Day", "Week", "Month", "Year"]
var frequencyPicker = UIPickerView()

var habitToEdit: HabitItem?
weak var delegate: HabitDetailViewControllerDelegate?

@IBAction func cancel() {
    delegate?.habitDetailViewControllerDidCancel(self)
}

@IBAction func done() {
    print("You plan to do \(habitNameField.text!) \(goalField.text!) times a \(frequencyField.text!.lowercaseString).")
    if let habit = habitToEdit {
        habit.name = habitNameField.text!
        habit.numberLeft = Int(goalField.text!)!
        habit.frequency = frequencyField.text!
        delegate?.habitDetailViewController(self, didFinishEditingHabit: habit)
    } else {
        let habit = HabitItem()
        habit.name = habitNameField.text!
        habit.numberLeft = Int(goalField.text!)!
        habit.frequency = frequencyField.text!
        habit.completed = false
        delegate?.habitDetailViewController(self, didFinishAddingHabit: habit)
    }
}

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
    habitNameField.becomeFirstResponder()
    frequencyPicker.hidden = false
}

override func viewDidLoad() {
    super.viewDidLoad()
    frequencyPicker.dataSource = self
    frequencyPicker.delegate = self
    doneBarButton.enabled = false
    habitNameField.addTarget(self, action: "checkFields:", forControlEvents: .EditingChanged)
    goalField.addTarget(self, action: "checkFields:", forControlEvents: .EditingChanged)
    frequencyField.addTarget(self, action: "checkFields:", forControlEvents: .EditingChanged)
    frequencyField.inputView = frequencyPicker
    if let habit = habitToEdit {
        title = "Edit Item"
        habitNameField.text = habit.name
        goalField.text = String(habit.numberLeft)
        doneBarButton.enabled = true
    }
}

override func tableView(tableView: UITableView, willSelectRowAtIndexPath indexPath: NSIndexPath) -> NSIndexPath? {
    return nil
}

func textField(habitNameField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let oldHabitNameText: NSString = habitNameField.text!
    let newHabitNameText: NSString = oldHabitNameText.stringByReplacingCharactersInRange(range, withString: string)
    doneBarButton.enabled = (newHabitNameText.length != 0)
    return true
}

func checkFields(sender: UITextField) {
    sender.text = sender.text?.stringByTrimmingCharactersInSet(.whitespaceCharacterSet())
    guard
        let habit = habitNameField.text where !habit.isEmpty,
        let goal = goalField.text where !goal.isEmpty,
        let frequency = frequencyField.text where !frequency.isEmpty
        else { return }
    // enable your button if all conditions are met
    doneBarButton.enabled = true
}

最佳答案

Xcode 9 • Swift 4

您可以addTarget 到您的文本字段以监视控件事件.editingChanged 并为所有这些使用单一选择器方法:

override func viewDidLoad() {
    super.viewDidLoad()
    doneBarButton.isEnabled = false
    [habitNameField, goalField, frequencyField].forEach({ $0.addTarget(self, action: #selector(editingChanged), for: .editingChanged) })
}

创建选择器方法并使用 guard 结合 where 子句(Swift 3/4 使用逗号)来确保所有文本字段不为空，否则直接返回。 Swift 3 不需要 @objc，但 Swift 4 需要:

@objc func editingChanged(_ textField: UITextField) {
    if textField.text?.characters.count == 1 {
        if textField.text?.characters.first == " " {
            textField.text = ""
            return
        }
    }
    guard
        let habit = habitNameField.text, !habit.isEmpty,
        let goal = goalField.text, !goal.isEmpty,
        let frequency = frequencyField.text, !frequency.isEmpty
    else {
        doneBarButton.isEnabled = false
        return
    }
    doneBarButton.isEnabled = true
}

sample

关于ios - 仅当所有文本字段都已填写时才在 Swift 中启用按钮，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34941069/