Programmatically adding UILabels and UIButtons to UIScrollView in Swift - ios

Question

My goal is to programmatically create multiple UILabels and UIButtons followed by programmatically creating and inserting them into a UIScrollView.
I am operating within the following class.
class ViewController: UIViewController {
I have first created my scrollView shown below.
#IBOutlet weak var scrollView: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
createTitleBar() //Function that creates fixed buttons and labels not included in scrollView
createUpperTabs() //Function that creates fixed buttons and labels not included in scrollView
createLowerNavBars() //Function that creates fixed buttons and labels not included in scrollView
for _ in 0...10 {
createTemplate() //This function consists of nested functions that creates labels and buttons that are then added to the scrollView
}
scrollView = UIScrollView(frame: view.bounds)
scrollView.backgroundColor = UIColor.black
scrollView.contentSize = CGSize(width: screenSize.width, height: currentStackY)
scrollView.autoresizingMask = UIViewAutoresizing.flexibleHeight
view.addSubview(scrollView)
}
After creating the labels and buttons, I add the views individually to the scrollView with following statement
self.scrollView.addSubview(UILabel or UIButton Name).
Here are some snippets showing how I am creating my UILabel and UIButton.
let titleHeader = UILabel()
self.scrollView.addSubview(titleHeader)
currentStackY += 8
titleHeader.backgroundColor = .gray
titleHeader.text = headerTitle
titleHeader.font = UIFont(name: buttonFont, size: buttonFontSize)
let labelWidth = titleHeader.intrinsicContentSize.width + 16
titleHeader.snp.makeConstraints { (make) in
make.height.equalTo(titleHeader)
make.width.equalTo(titleHeader)
make.top.equalTo(currentStackY)
make.left.equalTo(view).offset(8)
}
as well as
for i in 0...chiefComplaintArray.count - 1 {
let btn = UIButton()
chiefComplaintButton.append(btn)
buttonDictionary[chiefComplaintButton[i]] = numberButtonPressed
chiefComplaintButton[i].setTitle(chiefComplaintArray[i], for: .normal)
chiefComplaintButton[i].setTitleColor(UIColor.black, for: .normal)
chiefComplaintButton[i].titleLabel!.font = UIFont(name: buttonFont, size: buttonFontSize)
chiefComplaintButton[i].backgroundColor = UIColor.gray
chiefComplaintButton[i].sizeToFit()
let buttonWidth = chiefComplaintButton[i].frame.width + 10
let buttonHeight = chiefComplaintButton[i].frame.height + 5
if i == 0 {
currentStackX = 20
currentStackY += 5
} else if (currentStackX + buttonWidth) > screenSize.width {
currentStackX = 20
currentStackY += buttonHeight + 5
}
chiefComplaintButton[i].frame = CGRect(x: currentStackX, y: currentStackY, width: buttonWidth, height: buttonHeight)
currentStackX += chiefComplaintButton[i].frame.width + 5
if i == chiefComplaintArray.count - 1 {
currentStackY += chiefComplaintButton[i].frame.height
}
self.scrollView.addSubview(chiefComplaintButton[i])
chiefComplaintButton[i].addTarget(self, action: #selector(self.buttonPressed), for: .touchUpInside)
}
I used similar statements to add all of the created content to the scrollView. I have modeled my UIScrollView after other solutions in the stacks as well as other online references. Thanks in advance for your time and consideration.
I have subsequently tried
let titleHeader = UILabel()
scrollView.addSubview(titleHeader)
self.view.addSubview(scrollView)
currentStackY += 8
titleHeader.backgroundColor = .gray
titleHeader.text = headerTitle
titleHeader.font = UIFont(name: buttonFont, size: buttonFontSize)
let labelWidth = titleHeader.intrinsicContentSize.width + 16
Still getting the same error.

Answer 1

The issue with your code is you are initializing your scrollView after you are calling the method in which you are getting crash,because at that time your scrollView is nil.
You need to call your method after
view.addSubview(scrollView)
Edit
override func viewDidLoad() {
super.viewDidLoad()
for _ in 0...10 {
createTemplate() //This function consists of nested functions that creates labels and buttons that are then added to the scrollView
}
scrollView = UIScrollView(frame: view.bounds)
scrollView.backgroundColor = UIColor.black
scrollView.contentSize = CGSize(width: screenSize.width, height: currentStackY)
scrollView.autoresizingMask = UIViewAutoresizing.flexibleHeight
view.addSubview(scrollView)
createTitleBar() //Function that creates fixed buttons and labels not included in scrollView
createUpperTabs() //Function that creates fixed buttons and labels not included in scrollView
createLowerNavBars() //Function that creates fixed buttons and labels not included in scrollView
}
Also from here
let titleHeader = UILabel()
scrollView.addSubview(titleHeader)
self.view.addSubview(scrollView)
currentStackY += 8
titleHeader.backgroundColor = .gray
titleHeader.text = headerTitle
titleHeader.font = UIFont(name: buttonFont, size: buttonFontSize)
let labelWidth = titleHeader.intrinsicContentSize.width + 16
remove this
self.view.addSubview(scrollView)