点击时更改按钮的文本颜色

Question

I'm trying to get a button's text to change font color to red when tapped. I looked at similar posts from months ago and use of that code causes a build error in Xcode 6.1.1. Here is the code I'm trying:

class ViewController: UIViewController {

    @IBAction func firstButton(sender: UIButton) { 
        firstButton.titleLabel.textColor = UIColor.redColor()
    }
}

The error code that I get is:

'(UIButton) -> ()' does not have a member named 'titleLabel'

Any help will be much appreciated as I see Swift as my saving grace after having lost patience in trying to learn Objective C.

Answer 1

For anyone interested in the exact swift code necessary to make this question of mine work, here it is:

class ViewController: UIViewController {

@IBAction func firstButton(sender: UIButton) {

    sender.setTitleColor(UIColor.redColor(), forState: UIControlState.Normal)

}

Answer 2

You're trying to change the text color of the function's titleLabel , which doesn't make sense. You should be accessing sender parameter instead if you're trying to get a reference to the button to get at its titleLabel . Additionally, as rakeshbs points out, titleLabel is an optional property of UIButton.

class ViewController: UIViewController {

    @IBAction func firstButton(sender: UIButton) {
        sender.titleLabel?.textColor  = UIColor.redColor()
    }
}

If you break down your error message, you'll realize that this is clearly the issue.

'(UIButton) -> ()' does not have a member named 'titleLabel'

Which states that you are trying to access a member (or property) named titleLabel on an object of type (UIButton) -> () , which means a function that takes a button as input and returns nothing.

Answer 3

this will work for Swift 3 :

yourButton.setTitleColor(UIColor.blue, for: .normal)

Answer 4

UIButton.titlelabel is an optional property. You have to use optional chaining for changing its properties.

firstButton.titleLabel?.backgroundColor = UIColor.redColor()

Please read about swift optionals to understand this in detail. http://www.appcoda.com/beginners-guide-optionals-swift/