NSAttributedStringKey giving an unresolved identifier error

Question

I\'m following an online tutorial to build a magazine type iOS application. I\'m attempting to use NSAttributedStringKey but keep getting the error shown below. Any ideas?

Answer 1

Swift 4.x

 // MARK: - Deal with the empty data set
// Add title for empty dataset
func title(forEmptyDataSet _: UIScrollView!) -> NSAttributedString! {
    let str = "Welcome"
    let attrs = [NSAttributedStringKey.font: UIFont.preferredFont(forTextStyle: UIFontTextStyle.headline)]
    return NSAttributedString(string: str, attributes: attrs)
}

// Add description/subtitle on empty dataset
func description(forEmptyDataSet _: UIScrollView!) -> NSAttributedString! {
    let str = "Tap the button below to add your first grokkleglob."
    let attrs = [NSAttributedStringKey.font: UIFont.preferredFont(forTextStyle: UIFontTextStyle.body)]
    return NSAttributedString(string: str, attributes: attrs)
}

// Add your image
func image(forEmptyDataSet _: UIScrollView!) -> UIImage! {
    return UIImage(named: "MYIMAGE")
}

// Add your button
func buttonTitle(forEmptyDataSet _: UIScrollView!, for _: UIControlState) -> NSAttributedString! {
    let str = "Add Grokkleglob"
    let attrs = [NSAttributedStringKey.font: UIFont.preferredFont(forTextStyle: UIFontTextStyle.callout), NSAttributedStringKey.foregroundColor: UIColor.white]
    return NSAttributedString(string: str, attributes: attrs)
}

// Add action for button
func emptyDataSetDidTapButton(_: UIScrollView!) {
    let ac = UIAlertController(title: "Button tapped!", message: nil, preferredStyle: .alert)
    ac.addAction(UIAlertAction(title: "Hurray", style: .default, handler: nil))
    present(ac, animated: true, completion: nil)
}

Answer 2

Swift 4.1 and Xcode 9.3 changes Attributed key value.

let strName = "Hello Stackoverflow"
let string_to_color2 = "Hello"        
let attributedString1 = NSMutableAttributedString(string:strName)
let range2 = (strName as NSString).range(of: string_to_color2)       
attributedString1.addAttribute(NSAttributedStringKey.foregroundColor, value: UIColor.red , range: range2)
lblTest.attributedText = attributedString1

Hello will be in red color.

Answer 3

This example works only iOS11.

import UIKit

class VC: UIViewController { 

    @IBOutlet weak var usernameTxt: UITextField!
    @IBOutlet weak var emailTxt: UITextField!
    @IBOutlet weak var passTxt: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        setupView()
    }

    func setupView() {
        usernameTxt.attributedPlaceholder = NSAttributedString(string: "username", attributes: [NSAttributedStringKey.foregroundColor: smackPurplePlaceholder])
        emailTxt.attributedPlaceholder = NSAttributedString(string: "email", attributes: [NSAttributedStringKey.foregroundColor: smackPurplePlaceholder])
        passTxt.attributedPlaceholder = NSAttributedString(string: "password", attributes: [NSAttributedStringKey.foregroundColor: smackPurplePlaceholder])  
    }    
}

Answer 4

The projects are probably in different versions of Swift.

In Swift 4, NSFontAttributeName has been replaced with NSAttributedStringKey.font.

as stated here NSFontAttributeName vs NSAttributedStringKey.font

Need to confirm whether it will work on versions less than ios11

Answer 5

You are trying to use an iOS 11 API on a pre-iOS 11 version (likely iOS 10). Surprised that you found a tutorial already using beta features!

In the meantime, try this.

let attrs = [NSForegroundColorAttributeName: color, NSFontAttributeName: font]

and that should work.

Answer 6

The code you are trying to use is a new API added in iOS 11. Since you are using Xcode 8 you are not using iOS 11. So you need to use the current (non-beta) API.

let attrs = [NSForegroundColorAttributeName: color, NSFontAttributeName: font]