NSAttributedString with multiple alignments

Question

I have a UILabel where I would like to have three texts with three alignments: left, center and right. I found the following solution that works with left and right alignment, but I cannot add the center one:

    text = "Pause\n09:30 - 11:30\nsome center text"
    at = NSMutableAttributedString(string: text)
    p1.alignment = .left
    p2.alignment = .right
    p3.alignment = .center
    p2.paragraphSpacingBefore = -labelPause.font.lineHeight
    at.addAttribute(.paragraphStyle, value: p1, range: NSRange(location: 0, length: 4))
    at.addAttribute(.paragraphStyle, value: p3, range: NSRange(location: 4, length: 6))
    at.addAttribute(.paragraphStyle, value: p2, range: NSRange(location: 6, length: 8))
    labelPause.numberOfLines = 0
    labelPause.attributedText = at

The text that should be in the center just appears in the next line left-aligned. What am I doing wrong?

Answer 1

Some of your NSRanges don't match the character offsets you seem to want to target.

Try this in a playground, it works for me:

import UIKit
import PlaygroundSupport

let text = "Pause\n09:30 - 11:30\nsome centered text"
let at = NSMutableAttributedString(string: text)
let label = UILabel(frame: CGRect(x: 0, y: 0, width: 400, height: 60))
var p1 = NSMutableParagraphStyle()
var p2 = NSMutableParagraphStyle()
var p3 = NSMutableParagraphStyle()

p1.alignment = .left
p2.alignment = .right
p3.alignment = .center
p2.paragraphSpacingBefore = -label.font.lineHeight
p3.paragraphSpacingBefore = -label.font.lineHeight

at.addAttribute(.paragraphStyle, value: p1, range: NSRange(location: 0, length: 5))
at.addAttribute(.paragraphStyle, value: p3, range: NSRange(location: 20, length: 6))
at.addAttribute(.paragraphStyle, value: p2, range: NSRange(location: 6, length: 13))


label.numberOfLines = 0
label.attributedText = at

PlaygroundPage.current.liveView = label