tab-list-indent.swift

let items = [
    "Cats walking down to the mall to hang out at the water fountain",
    "Dogs catching tennis balls by the hotel pool",
    "Fish doing backflips as they hone their circus aspirations"
]

let mainAttributedString = NSMutableAttributedString()

for (index, item) in items.enumerated() {
    // Get the highest number however you want, this is hardcoded for sake of example
    let highestNumber = 577
    
    // Ternary hell, don't judge
    let numberPrefix = index == 0 ? 1 : index == 1 ? 22 : highestNumber
    
    let font = UIFont.systemFont(ofSize: 15.0)
    let tabWidth: CGFloat = 15.0
    
    // If you don't ceil this it won't format properly, probably internal integer rounding
    let prefixWidth = ceil(NSAttributedString(string: "\(highestNumber).", attributes: [.font: font]).size().width)
    
    let itemParagraphStyle = NSMutableParagraphStyle()
    itemParagraphStyle.tabStops = [
        NSTextTab(textAlignment: .right, location: prefixWidth),
        NSTextTab(textAlignment: .left, location: prefixWidth + tabWidth)
    ]
    
    itemParagraphStyle.headIndent = prefixWidth + tabWidth
    
    let itemAttributedString = NSAttributedString(string: "\t\(numberPrefix).\t\(item)\n", attributes: [.font: font, .foregroundColor: UIColor.black, .paragraphStyle: itemParagraphStyle])
    mainAttributedString.append(itemAttributedString)
}

label.attributedText = mainAttributedString