如何以编程方式快速添加自定义UIButton

Question

I was able to create a custom checkbox button class. However, when I attempt to place the button in my view, I don't get an image. Setting the background color simply returns a square of that size. Here is my code for adding the box:

     let box:CheckBox = CheckBox()
     box.frame = CGRectMake(screenSize.width/2, screenSize.height/2, 200, 200)
     self.view.addSubview(box)

I created the class as follows:

class CheckBox: UIButton {
    override init(frame: CGRect) {
        super.init(frame: frame)
        //other stuff
    }
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    // Images
    let checkedImage = UIImage(named: "checked_checkbox")
    let uncheckedImage = UIImage(named: "checkbox_unchecked_icon")

    // Bool property
    var isChecked: Bool = false {
        didSet{
            if isChecked == true {
                self.setImage(checkedImage, forState: .Normal)
            } else {
                self.setImage(uncheckedImage, forState: .Normal)
            }
        }
    }

    override func awakeFromNib() {
        self.addTarget(self, action: "buttonClicked:", forControlEvents: UIControlEvents.TouchUpInside)
        self.isChecked = false
    }

    func buttonClicked(sender: UIButton) {
        if sender == self {
            if isChecked == true {
                isChecked = false
            } else {
                isChecked = true
            }
        }
    }
}

Answer 1

Move your awakeFromNib code into your init() . awakeFromNib is only called when you're initialising from a nib/xib file.

This never gets called. You can test this by setting a breakpoint.

This is how it should look:

override init(frame: CGRect) {
    super.init(frame: frame)
    self.addTarget(self, action: "buttonClicked:", forControlEvents: UIControlEvents.TouchUpInside)
    self.isChecked = false
}

This way, self.isChecked gets called, an image is set, and you'll see more than a grey box.