Implementing Delegate Protocol - swift

Question

I am attempting to implement a delegate protocol but I am apparently doing it all wrong. I am using a cocoapod: https://cocoapods.org/pods/SMDatePicker, which I have attempted to contact the developer for assistance but so far he's never responded to me.
After I added the pod and installed it, I added the .swift file to my project and added the following method which displays the date picker just fine:
class CalculatorViewController: UIViewController, SMDatePickerDelegate {
#IBOutlet weak var lblDate: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Initialize
let tap = UITapGestureRecognizer(target: self, action: #selector(CalculatorViewController.tapFunction))
lblDate.isUserInteractionEnabled = true
lblDate.addGestureRecognizer(tap)
// Set label date
let dt = Date()
lblDate.text = dt.asString(style: .short)
}
#IBAction func datePicker(picker: SMDatePicker, didPickDate date: NSDate) {
let picked = date as Date
lblDate.text = picked.asString(style: .short)
}
#IBAction func tapFunction(sender: UITapGestureRecognizer) {
var picker: SMDatePicker = SMDatePicker()
picker.pickerMode = .date
picker.showPickerInView(view, animated: true)
print("tap working")
}
func datePicker(_ picker: SMDatePicker, didPickDate date: Date) {
let picked = date
print(date)
}
}
I am trying to get the result from the date picker. According to the pod the various methods are as follows:
// Initialize
var picker: SMDatePicker = SMDatePicker()
// Set delegate
picker.delegate = self
You have SMDatePickerDelegate protocol to handle picker’s events. Here are list:
datePickerWillAppear(picker: SMDatePicker)
datePickerDidAppear(picker: SMDatePicker)
datePicker(picker: SMDatePicker, didPickDate date: NSDate)
datePickerDidCancel(picker: SMDatePicker)
datePickerWillDisappear(picker: SMDatePicker)
datePickerDidDisappear(picker: SMDatePicker)
My problem is I'm not sure how to implement this, any help would be greatly appreciated.

Answer 1

You never set the delegate of your SMDatePicker. Also, you have two renditions of didPickDate. The correct syntax in Swift is datePicker(_:didPickDate:), where the second parameter is a Date, not a NSDate.
Thus:
class ViewController: UIViewController {
#IBOutlet weak var dateLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Initialize
let tap = UITapGestureRecognizer(target: self, action: #selector(didTapLabel(_:)))
dateLabel.isUserInteractionEnabled = true
dateLabel.addGestureRecognizer(tap)
// Set label date
let now = Date()
dateLabel.text = now.asString(style: .short)
}
#objc func didTapLabel(_ gesture: UITapGestureRecognizer) {
let picker = SMDatePicker()
picker.delegate = self // Don’t forget to set the delegate
picker.pickerMode = .date
picker.showPickerInView(view, animated: true)
print("tap working")
}
}
extension ViewController: SMDatePickerDelegate {
func datePicker(_ picker: SMDatePicker, didPickDate date: Date) {
dateLabel.text = date.asString(style: .short)
}
}
I personally would put the SMDatePickerDelegate methods in its own extension, just to keep the code nice and organized. Also, your tap gesture recognizer can just be declared as #objc, not #IBAction (as the latter suggests you’re hooking it up to an action in Interface Builder (hence the IB), whereas you’re just hooking it up via an Objective-C #selector pattern).

Answer 2

First, add an outlet to CalculatorViewController that references the date picker in your storyboard/XIB.
Then, in viewDidLoad(), assign your class as its delegate.
#IBOutlet weak var datePicker: SMDatePicker!
override func viewDidLoad() {
self.datePicker.delegate = self
}
The class that you add as its delegate must conform to the SMDatePickerDelegate protocol, which your example does.
Then, simply add the methods to your class to react to its events. For example:
func datePicker(picker: SMDatePicker, didPickDate date: NSDate) {
debugPrint("date picked! \(date)")
}
func datePickerDidCancel(picker: SMDatePicker) {
debugPrint("date picker cancelled")
}