UILabel shows wrong Localized String - ios

Question

I have a problem with localizing a string through the Localizable.stringdict. I did setup different localization for different sizes of a Test string. See Localizable.stringdict:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Test</key>
<dict>
<key>NSStringVariableWidthRuleType</key>
<dict>
<key>20</key>
<string>test</string>
<key>25</key>
<string>test message</string>
<key>50</key>
<string>This is a test message</string>
</dict>
</dict>
</dict>
</plist>
My ViewController looks like the following:
class ViewController: UIViewController {
#IBOutlet weak var label: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let string = NSLocalizedString("Test", comment: "This is a test message") as NSString
let widthFormattedString = string.variantFittingPresentationWidth(50) as String
print(widthFormattedString)
label.text = widthFormattedString
}
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
I would like to assign the localized string to a label. The print in my ViewController is printing "This is a test message", but the view is showing "test message". I don't change the text of the label anywhere else. So I wonder why the wrong message is displayed. Can anyone help?

Answer 1

According to the documentation at writing this answer it states that:
Note
Don't call this method when setting user-visible text for standard UIKit controls, such as UILabel. UIKit provides built-in support for adaptive strings, and automatically selects the string width variant appropriate for the current screen size according to the behavior described below.
which seems to confirm what you experience.
The print out you do yourself is correct because it delivers you the string you requested for the value 50:
The print in my ViewController is printing "This is a test message"
Whereas the UILabel gets a the string by the UIKit standard mechanism and appears as:
but the view is showing "test message"
I conclude that you don't need to do it yourself if you use UIKit controls. This is probably helpful for custom controls or other use cases I'm not aware of.