create UILabel via function-CodePudding

First of all, I would like to say that I am aware that my approach may be a bit naive, but I have not been programming in Swift for so long and you may forgive my ignorance at this point.

I am currently trying to create UILabels programmatically and in the process I came up with the idea - because the basic properties of the labels basically don't change - to write a function that does this work for me. Apart from the fact that it saves a lot of code.

In the end I want to create labels with different names, whose properties (constraints) I can edit externally with my own functions.

My function, as you see it here, "produces" labels but nothing comes out that Xcode can do anything with.

func createValueLabel(placeHolderValue text: String, labelName name: String) -> UILabel {
    let label = UILabel()

    label.layer.name = name
    label.font = UIFont.boldSystemFont(ofSize: 14)
    label.text = text
    label.textColor = UIColor.init(red: 188 / 255, green: 143 / 255, blue: 143 / 255, alpha: 1.0)
    resourceView.addSubview(label)
    //label.translatesAutoresizingMaskIntoConstraints = false

    return label
}

I would like to put the labels, once they are produced, into a subView.

Is my project basically doomed to fail or am I just being too stupid?

Thanks in advance.

CodePudding user response：

UILabel is a reference type(Class) As you are returning the label in your method you can assign it to a new variable like:

var myNewLabel = createValueLabel(...)

and later you can change it's property whenever you want like

myNewLabel.text = "newLabelText"

CodePudding user response：

Firstly refactor your creating label to only create label without adding it to view

func createValueLabel(placeHolderValue text: String, labelName name: String) -> UILabel {
    let label = UILabel()
    label.layer.name = name
    label.font = UIFont.boldSystemFont(ofSize: 14)
    label.text = text
    label.textColor = UIColor.init(red: 188 / 255, green: 143 / 255, blue: 143 / 255, alpha: 1.0)
    return label
}

Then add your label into your view, for example in UIViewController method viewDidLoad and add proper constraints:

override func viewDidLoad() {
    super.viewDidLoad()
    let label = createValueLabel(placeHolderValue: "", labelName: "")
    //adding label to view
    self.view.addSubview(label)
    //adding constraints to labels
    label.translatesAutoresizingMaskIntoConstraints = false
    label.leadingAnchor.constraint(equalTo: self.view.leadingAnchor,constant: 10).isActive = true
    label.trailingAnchor.constraint(equalTo: self.view.trailingAnchor,constant: 10).isActive = true
    label.topAnchor.constraint(equalTo: self.view.topAnchor,constant: 10).isActive = true
    label.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: 10).isActive = true
}

CodePudding user response：

If you're creating the label inside a UIViewController class programmatically, following way is considered a good practice:

let myNewLabel: UILabel = {
    let lbl = UILabel()
    lbl.frame = CGRect(x: 0, y: 0, width: 100, height: 100) //setting frame here or you can change later as well
    lbl.backgroundColor = .white
    lbl.font = UIFont.boldSystemFont(ofSize: 14)
    lbl.textColor = UIColor.init(red: 188 / 255, green: 143 / 255, blue: 143 / 255, alpha: 1.0)
    lbl.translatesAutoresizingMaskIntoConstraints = false //make sure this property is false when programmatically setting constraints
    return lbl
}()

You can later access this property via myNewLabel in viewDidLoad:

override func viewDidLoad() {
    super.viewDidLoad()
    setupMyNewLabel(placeHolderValue: "placeholderValue", labelName: "name")
}

It's good to refactor code based on what purpose each line serve.

fileprivate func setupMyNewLabel(placeHolderValue text: String, labelName name: String) {
    myNewLabel.layer.name = name
    myNewLabel.text = text
    resourceView.addSubview(myNewLabel)

    //setup your constraints here
    myNewLabel.leadingAnchor.constraint(equalTo: self.view.leadingAnchor,constant: 10).isActive = true
    myNewLabel.trailingAnchor.constraint(equalTo: self.view.trailingAnchor,constant: 10).isActive = true
    myNewLabel.topAnchor.constraint(equalTo: self.view.topAnchor,constant: 10).isActive = true
    myNewLabel.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: 10).isActive = true
}

CodePudding user response：

Ok, I have found the error. I tried to change the constrains of the labels via a function and this function did not "know" the created labels, because I executed the function to create the labels in the viewDidLoad. So the created value or label were not global and therefore not recognized.