如何在Swift 4中获取按钮值？

Question

    @IBOutlet var button: UIButton!    
    func randomize(){
        var x_axis:CGFloat = 8.0
        var y_axis:CGFloat = 330.0
        for selected_Synonym in selected_Synonyms {
            button = UIButton.init(type: UIButtonType.custom) as UIButton
            button.frame = CGRect(x: x_axis, y: y_axis, width: 400, height: 50)
            button.backgroundColor = UIColor.black
            button.setTitle(selected_Synonym as? String, for: UIControlState.normal)
            button.setTitleColor(UIColor.white, for: [])
            button.addTarget(self, action: Selector(("pressed:")), for: UIControlEvents.touchUpInside)
            self.view.addSubview(button)
            x_axis = 10.0
            y_axis += 70.0
        }
    }

    func pressed(sender: Any){
        let buttonTitle = button.currentTitle
        print(buttonTitle)
    }

However when it runs and I press on a button I get the following error:

Thread 1: signal SIGABRT.

The program creates 5 buttons. I am new to swift and ios development would be very grateful if someone could help me out. Thank you.

Answer 1

You have several issues. To fix the crash, replace Selector(("pressed:")) with #selector(pressed) . The use of Selector is very out-of-date. Always use #selector .

Next, remove the @IBOutlet var button: UIButton! line. You don't need it.

Then change:

button = UIButton.init(type: UIButtonType.custom) as UIButton

to:

let button = UIButton(type: .custom)

Then update your pressed function to:

@objc func pressed(sender: UIButton){
    let buttonTitle = sender.currentTitle
    print(buttonTitle)
}

Note the addition of @objc . This is required for any function being used with a target/selector. Also note that sender is now UIButton instead of Any . It's best to set the sender's type to match the proper type.

Here's all of your code with lots of little fixes:

func randomize() {
    var xAxis: CGFloat = 8.0
    var yAxis: CGFloat = 330.0

    for selectedSynonym in selectedSynonyms {
        let button = UIButton(type: .custom)
        button.frame = CGRect(x: xAxis, y: yAxis, width: 400, height: 50)
        button.backgroundColor = .black
        button.setTitle(selectedSynonym, for: .normal)
        button.setTitleColor(.white, for: .normal)
        button.addTarget(self, action: #selector(pressed), for: .touchUpInside)
        self.view.addSubview(button)
        xAxis = 10.0
        yAxis += 70.0
    }
}

@objc func pressed(sender: UIButton){
    let buttonTitle = sender.currentTitle
    print(buttonTitle)
}

Use camelCase, not snake_case when naming variables and functions. Make use of Swift type inference.