Swift 3动态添加删除子视图及其内容

Question

I am writing my first Swift app for quiz. Each question has random way to render on screen as below screenshot.

I am programming app without story board ie. programmatically. I want to create simple pagination flow for each question within single viewcontroller without using Collocationview, Tableview or navigation.

What I did so far? I have simple viewcontroller with UIView() added as subview. I am adding question components dynamically. Now once user click on continue I wanted remove subview and add new subview with new question. I am able to remove subview but contents on subview seems to be still there as I can see its overwriting.

To get more clarification please view my code.

import UIKit

class QuizController: UIViewController {

let subView = UIView()
var currentQuestion:Int = 1;


let questions = ["This is question 1", "Hello to question 2", "Question 3"]

override func viewDidLoad() {
    super.viewDidLoad()
    self.view.backgroundColor = .white
    setup_layout()
}

func setup_layout(){

    let closeBtn = UIButton(frame: CGRect(x: 5, y: 10, width: 200, height: 50))
    closeBtn.backgroundColor = UIColor.red
    closeBtn.setTitle("Close", for: .normal)
    closeBtn.addTarget(self, action: #selector(close), for: .touchUpInside)
    view.addSubview(closeBtn)
    //dynamic view
    create_subview()
}

func nextQuestion(){
    print("Show next")
    if let viewWithTag = self.view.viewWithTag(currentQuestion) {
        viewWithTag.removeFromSuperview()
        currentQuestion += 1;
        create_subview()
    } else {
        print("No!")
    }


}

func create_subview(){

    let heightOfView = view.frame.size.height
    let widthOfView = view.frame.size.width

    subView.tag = currentQuestion
    subView.backgroundColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.2)
    subView.frame = CGRect(x: 0, y: 60, width: self.view.frame.width, height: heightOfView - 60)
    self.view.addSubview(subView)

    let txtLabel1 = UILabel(frame: CGRect(x: 35, y: 120, width: widthOfView , height: 20))
    txtLabel1.text = questions[currentQuestion-1]
    txtLabel1.font = txtLabel1.font.withSize(12)
    subView.addSubview(txtLabel1)

    let nextBtn = UIButton(frame: CGRect(x: 5, y: 300, width: 200, height: 50))
    nextBtn.backgroundColor = UIColor.red
    nextBtn.setTitle("Continue", for: .normal)
    nextBtn.addTarget(self, action: #selector(nextQuestion), for: .touchUpInside)
    subView.addSubview(nextBtn)

}

func close(){
    self.dismiss(animated: true, completion: nil)
}

}

And this is what I see which I click continue.

NOTE: Initially thought using Collocation or Table view will be more appropriate as I can set to scroll horizontally for each question and fetch questions using REST API and place to each cell. But I want to present next screen to user only once then click on continue. I guess with collectionview user can move to next screen on swipe.

Answer 1

Just found the answer. I assumed removing subview will also remove all components on subview by itself ie. UILable and UIButton in my case.

I have to remove them separately.

for subview in self.subView.subviews {
       subview.removeFromSuperview()
}

Now i can add tag to components and remove like this:

    for subview in self.subView.subviews {
        if (subview.tag == 1) {
            subview.removeFromSuperview()
        }
    }

Answer 2

Why are you removing superviews and adding again and again?? Simply change UILabel.text :)