iOS 9 Swift UIButton CheckBox子类未显示图像

Question

I subclassed UIButton to make a CheckBox ... The code below seems to work on storyboard (according to online tutorials) but when i try to add it by code it doesn't work...

class CheckBox: UIButton {

    // Images
    let checkedImage = UIImage(named: "Checked.png")! as UIImage
    let uncheckedImage = UIImage(named: "Unchecked.png")! as UIImage

    // 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: #selector(CheckBox.buttonClicked(_:)), forControlEvents: UIControlEvents.TouchUpInside)
        self.isChecked = false
    }

    func buttonClicked(sender: UIButton) {
        if sender == self {
            isChecked = !isChecked
        }
    }
}

Here is the code I use on my ViewController to add the CheckBox:

let checkbox = CheckBox(frame: CGRect(x: 5, y: 5, width: 40, height: 40))
print(checkbox.isChecked)
view.addSubview(checkbox)

The problem is that the CheckBox is not being displayed. If I give it a background, under the frame initialization then I can see the square but if nothing happens when I click it.. Even after adding a print message in the buttonClicked method.

I added print statements in the awakeFromNib method and it was never called...

Answer 1

已修复..如果没有Storyboard，AwakeFromNib显然不会被调用，因此我必须实现一个便捷的初始化程序。