How to programmatically set line height for a UILabel with dynamic text?

Question

I have a UILabel that will vary in number of lines. I'm using a custom font, and want to set the line height of this label to something >1.

Answer 1

I'm not really familiar with KVO, but I use Rx, so I can suggest using this

import UIKit
import RxSwift
import RxCocoa

extension UILabel {
    private func setLineHeight(lineHeight: CGFloat) {
        var attributeStringInitial: NSMutableAttributedString?
        var textInitial: String?
        
        if let text_ = self.text {
            attributeStringInitial = NSMutableAttributedString(string: text_)
            textInitial = text_
        } else if let text_ = self.attributedText {
            attributeStringInitial = NSMutableAttributedString(attributedString: text_)
            textInitial = text_.string
        }
        
        guard let attributeString = attributeStringInitial,
              let text = textInitial
        else { return }
            
        let style = NSMutableParagraphStyle()
        
        style.lineSpacing = lineHeight
        attributeString.addAttribute(NSAttributedString.Key.paragraphStyle, value: style, range: NSMakeRange(0, text.count))
        self.attributedText = attributeString
    }
    
    func setLineHeight(lineHeight: CGFloat, disposeBag: DisposeBag) {
        rx.observe(String.self, "text")
            .subscribe(onNext: { [weak self] text in
                self?.setLineHeight(lineHeight: 10)
            })
            .disposed(by: disposeBag)
    }
}