UIBarButton doesn't show before section of code but shows after

Question

super.viewDidLoad()

let urlString: String
if navigationController?.tabBarItem.tag == 0 {
    urlString = "https://api.whitehouse.gov/v1/petitions.json?limit=100"
} else {
    urlString = "https://api.whitehouse.gov/v1/petitions.json?signatureCountFloor=10000&limit=100"
}

if let url = URL(string: urlString) {
    if let data = try? Data(contentsOf: url) {
        parse(json: data)
        return
    }
}

navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .action, target: self, action: #selector(actionButton))

If I create the rightBarButton after the section of code (like above) the bar button doesn't show up. However, if I create the rightBarButton before the code, the rightBarButton appears. I have a tableViewController embedded in a navigation controller and tab bar controller. Why does making the button after the code not show the button?

Answer 1

Remove the return keyword, return won't execute further lines of the code. please refer answer of confused with the functionality of return in swift .

Your code should be

super.viewDidLoad()
let urlString: String = (navigationController?.tabBarItem.tag == 0) ? "https://api.whitehouse.gov/v1/petitions.json?limit=100" : "https://api.whitehouse.gov/v1/petitions.json?signatureCountFloor=10000&limit=100"


if let url = URL(string: urlString) {
    if let data = try? Data(contentsOf: url) {
        parse(json: data)
    }
}
navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .action, target: self, action: #selector(actionButton)