rdar://30739102

ViewController.swift

//
//  ViewController.swift
//  AttributedString
//
//  Created by Peter Goldsmith on 27/02/2017.
//

import UIKit

class ViewController: UIViewController {

    @IBOutlet var label: UILabel!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let attributedString = NSMutableAttributedString()
        
        // Strikethrough attribute
        let strikeThroughAttributes: [String: Any] = [
            NSStrikethroughStyleAttributeName: NSUnderlineStyle.styleSingle.rawValue,
            NSForegroundColorAttributeName: UIColor.purple
        ]
        attributedString.append(NSAttributedString(string: "strikethrough", attributes: strikeThroughAttributes))
        
        // If the below is appended, in iOS 10.3 (built against any SDK), it will
        // prevent the strikethrough appearing from the PRECEEDING string.
        let nonStrikeThroughAttributes: [String: Any] = [
            NSStrikethroughStyleAttributeName: NSUnderlineStyle.styleNone.rawValue,
            NSForegroundColorAttributeName: UIColor.green
        ]
        
        attributedString.append(NSAttributedString(string: "no strikethrough", attributes: nonStrikeThroughAttributes))
       
        // Build and run attached project with Xcode 8.2 with iOS 10.2 simulator.
        // You should see "strikethrough" in purple that has a strikethrough, and "not strikethrough" in green that has no strikethrough.
        // Using Xcode 8.3 against iOS 10.3 simulator, you should see the same, however you see "strikethrough" without any strikethrough.
        label.attributedText = attributedString
    }
}