Infinite loop in UITextField subclass when overriding layoutSubviews

Could you show code for UITextField subclass ? Including viewLayout override of course.

We override

layoutSubviews

and set five background colours within it.

How are you setting these background colours? By modifying the text attributed string, for example, by setting

attributedText

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No attributes strings in this case. I've added the code below for the complete subclass.

This code doesn't crash at all on iOS 13.

It crashes *sometimes* on iOS 11 and 12 simulators with layoutSubviews in an infinite loop. Note it doesn't crash immediately or on first load. Sometimes it will take a couple of clicks within the text box or some letters being typed.

import UIKit


class FormTextField: UITextField {


    // MARK: Layout overrides
    override func textRect(forBounds bounds: CGRect) -> CGRect {
        return CGRect(x: bounds.origin.x + 10, y: bounds.origin.y, width: bounds.width + 10, height: bounds.height)
    }
    
    override func editingRect(forBounds bounds: CGRect) -> CGRect {
        return CGRect(x: bounds.origin.x + 10, y: bounds.origin.y, width: bounds.width + 10, height: bounds.height)
    }
    
    // MARK: Private properties
    private var hintText: String?
    
    // MARK: Life Cycle
    init(hintText: String? = nil) {
        super.init(frame: .zero)
        
        self.autocapitalizationType = .none
        self.autocorrectionType = .no
        self.spellCheckingType = .no
        self.font = UIFont.font(type: .helveticaNeueRegular, size: 15)
        self.layer.borderColor = UIColor.mswGrayLight.cgColor
        self.layer.borderWidth = 0.5
        self.layer.cornerRadius = 2
        self.hintText = hintText
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        styleViews()
    }
    
    // MARK: Theme Support
    private func styleViews() {
        self.layer.borderColor = UIColor.textAreaOutline.cgColor
        self.tintColor = .mswLightBlue
        self.textColor = .textFieldText
    }
}

Why do you call styleViews() on layout and not only at init ?

Could you try the change ?

Could you see the pattern of infinite loop ?

Does it involve textRect and / or editingRect ?

Is it called in layoutSubviews to support dark mode. layoutSubviews is called on all views when the system dark mode setting is turned on or off. The colour specified have a light and dark variety.

Removing the textRect and editingRect does not stop the issue. If I remove the line

self.textColor = .textFieldText 

The crash doesn not occur, so it seems this line is causing an issue.

I recreate it by having two text fields and;

- focus on first text field and type a letter

- focus on second text field and type a letter

- attempt to focus on the first text field - at this point layoutSubviews goes into an infinite loop.