在预期会迅速返回的函数中缺少返回

Question

I want to make a button that makes the background switch between red and green but I get this error:

missing return in a function expected to return UIView

I'm pretty new to coding, I've googled a bit but I didn't find anything.

Language:Swift

my code:

var timeLeft = 0
import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    var buttonColor: UIView! {

        timeLeft = 1
    }

    func update() {
        if timeLeft > 0 {
            view.backgroundColor = UIColor.greenColor()
        }
        else {

            view.backgroundColor = UIColor.redColor()
        }
        timeLeft = timeLeft - 1

    }
}

thanks for helping

Answer 1

You declare buttonColor as a computed property which in its body requires you to return a UIView instance (since its type is UIView ).

Read here or here about computed property and make sure it fits your needs as posted in your case

Answer 2

Hi and welcome to stackoverflow

Remember to make an action connecting your UIButton to the code. Otherwise your code will not run when you click on the button. Also, consider using a Bool (true/false) variable to keep track of the background color.

Try the following code (remember to connect the 'click'-function to the button via the storyboard):

import UIKit

class ViewController: UIViewController {

    var isGreen = true

    @IBAction func click() {
        if isGreen {
            view.backgroundColor = UIColor.redColor()
            isGreen = false
        } else {
            view.backgroundColor = UIColor.greenColor()
            isGreen = true
        }
    }
}

Answer 3

var buttonColor: UIView! { get() { return (Object of UIView) } }