如何在Swift中按下按钮来增加标签值

Question

I am trying to increment a label by 2 when I click a button.

import UIKit

class ViewController: UIViewController {

    var cur = 0;

    @IBOutlet weak var money: UILabel!

    @IBAction func pressbutton(sender: UIButton) {
        cur = money.text!.toInt()!;
        self.money.text = String(cur + 2);

    }

}

Here is my current code but I am getting the error

toInt() is unavaliable: Use Int() initializer

on this line

cur = money.text!.toInt()!;

Answer 1

You shouldn't be using the content of a label to increment your label according to MVC programming. Instead, use a variable to store your Int and update the label by adding a property observer to the variable like so:

class ViewController: UIViewController {

    @IBOutlet weak var someLabel: UILabel!

    var someValue: Int = 0 {
        didSet {
            someLabel.text = "\(someValue)"
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        someValue = 0 // didSet is called when the variable is changed, not upon initialization.
    }

    @IBAction func buttonPressed(sender: UIButton) {
        someValue += 2
    }
}

Also, I would consider renaming your variable to something more descriptive than cur , and you may omit the semicolons as they are unnecessary.

Answer 2

You can fix this error by changing the offending code to the following:

cur = Int(money.text!)!;

Read more about initializers here . An excerpt:

Initialization is the process of preparing an instance of a class, structure, or enumeration for use. This process involves setting an initial value for each stored property on that instance and performing any other setup or initialization that is required before the new instance is ready for use.

Answer 3

money.text = "\(Int(money.text!)! + 2)"