问题
I have two viewcontroller classes. MainViewController has a UITextField and SecondViewController has a UILabel. I want to print the text from the UITextField in the UILabe. Please tell me the best way to do this programmatically. Below is my code:
// AppDelegate.swift
import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
window = UIWindow(frame: UIScreen.main.bounds)
window?.makeKeyAndVisible()
window?.rootViewController = MainViewController()
window?.backgroundColor = UIColor.yellow
application.statusBarStyle = .lightContent
return true
}
}
// MainViewController Class
import UIKit
class MainViewController: UIViewController {
let label = UILabel()
let textField = UITextField()
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = UIColor.gray
setupLabel()
setupTextField()
setupButton()
}
func setupLabel() {
label.frame = CGRect(x: 40, y: 80, width: 300, height: 60)
label.text = "welcome to my world"
label.textColor = UIColor.yellow
label.font = UIFont.boldSystemFont(ofSize: 25)
label.textAlignment = .center
label.layer.borderWidth = 2
label.layer.borderColor = UIColor.yellow.cgColor
label.layer.cornerRadius = 5
view.addSubview(label)
}
func setupTextField() {
textField.frame = CGRect(x: 10, y: 200, width: self.view.frame.size.width - 20, height: 60)
textField.placeholder = "text here"
textField.textAlignment = .center
textField.font = UIFont.systemFont(ofSize: 25)
textField.layer.borderWidth = 2
textField.layer.borderColor = UIColor.yellow.cgColor
textField.layer.cornerRadius = 5
view.addSubview(textField)
}
func setupButton() {
let button = UIButton()
button.frame = CGRect(x: 50, y: 300, width: self.view.frame.size.width - 100, height: 60)
button.setTitle("Enter", for: .normal)
button.setTitleColor(UIColor.yellow, for: .normal)
button.layer.borderWidth = 2
button.layer.borderColor = UIColor.yellow.cgColor
button.layer.cornerRadius = 5
button.addTarget(self, action: #selector(buttonTarget), for: .touchUpInside)
view.addSubview(button)
}
func buttonTarget() {
// i missed here maybe
}
}
// SecondViewController class
import UIKit
class SecondViewController: UIViewController {
let secondLabel = UILabel()
override func viewDidLoad() {
super.viewDidLoad()
setupLabelSecond()
}
func setupLabelSecond() {
secondLabel.frame = CGRect(x: 40, y: 80, width: 300, height: 60)
secondLabel.text = "this is Second Page"
secondLabel.textColor = UIColor.yellow
secondLabel.font = UIFont.boldSystemFont(ofSize: 25)
secondLabel.textAlignment = .center
secondLabel.layer.borderWidth = 2
secondLabel.layer.borderColor = UIColor.yellow.cgColor
secondLabel.layer.cornerRadius = 5
view.addSubview(secondLabel)
}
}
回答1:
you need to follow some steps
step1
initially embed with your initial VC to navigation controller , for e.g
Now select the first controller in Storyboard and click on Editor > Embed in... > Navigation Controller.
step2
Now you have to link the second Controller in Storyboard with your new SecondViewController.swift file.
Select the yellow circle at the top of the controller, click on the Identify inspector panel icon on the right side of the XCode window, and type the name of your new .swift file in the Class and StoryboardID fields
for e.g
step3
Passing a String
Now select the other controller in Storyboard and add this variable right below the SecondViewController class declaration:
class SecondViewController: UIViewController {
let secondLabel = UILabel()
var stringPassed = ""
Make the app assign the value of this variable to secondLabel with the following line of code in the viewDidLoad() method
step4
on your first VC , inside the button
func buttonTarget() {
let myVC = storyboard?.instantiateViewControllerWithIdentifier("SecondVC") as! SecondViewController
myVC.stringPassed = label.text!
navigationController?.pushViewController(myVC, animated: true)
}
finally you get the out put as
func setupLabelSecond() {
secondLabel.frame = CGRect(x: 40, y: 80, width: 300, height: 60)
if let outputText = stringPassed
{
secondLabel.text = outputText
}else
{
secondLabel.text = "this is Second Page"
}
secondLabel.textColor = UIColor.yellow
secondLabel.font = UIFont.boldSystemFont(ofSize: 25)
secondLabel.textAlignment = .center
secondLabel.layer.borderWidth = 2
secondLabel.layer.borderColor = UIColor.yellow.cgColor
secondLabel.layer.cornerRadius = 5
view.addSubview(secondLabel)
}
for sample you can get the tutorial here
update for XIB
func buttonTarget() {
var vcPass = SecondViewController(nibName: "SecondViewController", bundle: nil)
vcPass.stringPassed = label.text!
self.navigationController?.pushViewController(vcPass, animated: true)
}
update for without XIB and Storboard
change your appdelegate
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
self.window = UIWindow(frame: UIScreen.main.bounds)
// Override point for customization after application launch.
let navigation = UINavigationController(rootViewController: MainViewController())
self.window?.rootViewController = navigation
self.window?.makeKeyAndVisible()
return true
}
on your MainViewController
func buttonTarget() {
var vcPass = SecondViewController()
vcPass.stringPassed = label.text!
self.navigationController?.pushViewController(vcPass, animated: true)
}
Passing a String
Now select the other controller in Storyboard and add this variable right below the SecondViewController class declaration:
class SecondViewController: UIViewController {
let secondLabel = UILabel()
var stringPassed = ""
Make the app assign the value of this variable to secondLabel with the following line of code in the viewDidLoad() method
func setupLabelSecond() {
secondLabel.frame = CGRect(x: 40, y: 80, width: 300, height: 60)
if let outputText = stringPassed
{
secondLabel.text = outputText
}else
{
secondLabel.text = "this is Second Page"
}
secondLabel.textColor = UIColor.yellow
secondLabel.font = UIFont.boldSystemFont(ofSize: 25)
secondLabel.textAlignment = .center
secondLabel.layer.borderWidth = 2
secondLabel.layer.borderColor = UIColor.yellow.cgColor
secondLabel.layer.cornerRadius = 5
view.addSubview(secondLabel)
}
回答2:
I know 2 possible ways.
1) Embed your initial view controller in navigation controller. In your 2nd view create a var. eg
var x = ""
in your 1st view create a text field outlet and object of second view controller ,
@IBOutlet weak var enteredName: UITextField!
let secondVC = self.storyboard?.instantiateViewController(withIdentifier: "secondViewController") as! secondViewController
then, assign the entered text field through that object to variable x.
secondVC.x = enteredName.text!
in your second vc you can assign the value of x to your label.
mylabel.text = x
____________________________________________________________________
Second Method is using user Defaults.
take user input and set that as user default.
let defaults = UserDefaults.standard
defaults.set(self.enteredName.text!,forKey: "userName")
defaults.synchronize()
and in your second view use
let defaults = UserDefaults.standard
yourlabel.text = defaults.object(forKey: "userName")
来源：https://stackoverflow.com/questions/42608097/passing-data-between-view-controllers-programmatically-swift