如何从 ActionSheet 更改 UIButton 的文本

Question

我想更改 UIButton city 的文字。

但它不起作用，你能告诉我这里有什么问题吗？这个 IBAction setUpCityDropDown 连接到同一个 UIButton。

 @IBAction func setUpCityDropDown()
        {
            let ActionSheet =  UIAlertController(title: "Which City?", message: "City Name", preferredStyle: UIAlertControllerStyle.ActionSheet)

            let cancelActionButton: UIAlertAction = UIAlertAction(title: "Cancel", style: .Cancel) { action -> Void in
            }
            let delhiActionActionButton : UIAlertAction = UIAlertAction(title: "Delhi", style: UIAlertActionStyle.Default)
            {   action -> Void in


                self.city.setTitle("Delhi", forState:  UIControlState.Normal)
                self.city.sizeToFit()

            }
            let mumbaiActionActionButton : UIAlertAction = UIAlertAction(title: "Mumbai", style: UIAlertActionStyle.Default)
            {
                action -> Void in
                self.city.setTitle("Mumbai", forState:  UIControlState.Normal)

                self.city.sizeToFit()
            }
            let ahmedabadActionButton : UIAlertAction = UIAlertAction(title: "Ahmedabad", style: UIAlertActionStyle.Default)
            {
                action -> Void in
                self.city.setTitle("Ahmedabad", forState:  UIControlState.Normal)

                self.city.sizeToFit()
            }

            ActionSheet.addAction(cancelActionButton)
            ActionSheet.addAction(ahmedabadActionButton)
            ActionSheet.addAction(delhiActionActionButton)
            ActionSheet.addAction(mumbaiActionActionButton)
            self.presentViewController(ActionSheet, animated: true, completion: nil)
        }

    }

Answer 1

当您在 IB 中为 UIButton 设置标题时，它设置的不是String，而是NSAttributedString。所以你需要使用setAttributedTitle(_:forState:)方法来改变它而不是setTitle(_:forState:)

@IBAction func setUpCityDropDown()
{
    let ActionSheet =  UIAlertController(title: "Which City?", message: "City Name", preferredStyle: .ActionSheet)
    let cancelActionButton: UIAlertAction = UIAlertAction(title: "Cancel", style: .Cancel) { action in }
    let delhiActionActionButton : UIAlertAction = UIAlertAction(title: "Delhi", style: .Default)
    {   
        action in
        self.city.setAttributedTitle(NSAttributedString(string: "Delhi"), forState: .Normal)
        self.city.sizeToFit()
    }
    let mumbaiActionActionButton : UIAlertAction = UIAlertAction(title: "Mumbai", style: .Default)
    {   
        action in
        self.city.setAttributedTitle(NSAttributedString(string: "Mumbai"), forState: .Normal)
        self.city.sizeToFit()
    }
    let ahmedabadActionButton : UIAlertAction = UIAlertAction(title: "Ahmedabad", style: .Default)
    {   
        action in
        self.city.setAttributedTitle(NSAttributedString(string: "Ahmedabad"), forState: .Normal)
        self.city.sizeToFit()
    }
    ActionSheet.addAction(cancelActionButton)
    ActionSheet.addAction(ahmedabadActionButton)
    ActionSheet.addAction(delhiActionActionButton)
    ActionSheet.addAction(mumbaiActionActionButton)
    self.presentViewController(ActionSheet, animated: true, completion: nil)
    }
}