从viewcontroller类绘图

Question

I made a class that inherits from UIView. In that class I want to draw a png image. However, when I run it in my viewcontroller, it doesn't seem to do anything. I read that we had to use setNeedsDisplay to be able to get the drawRect to be called in the viewcontroller. It doesn't seem to update.

class MyView: UIViewController{
    let tile = DrawTile()

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    @IBAction func Pressed(sender: AnyObject) {
         tile.setNeedsDisplay()

    }
}

class Draw: UIView {

    override func drawRect(rect: CGRect) {
        let context = UIGraphicsGetCurrentContext()
        let image = UIImage(named: "test.png")
        let location = CGPointMake(0, 0)
        image?.drawAtPoint(location)

    }
}

Answer 1

Are you initializing your view somewhere? drawRect() will only get called when you initialize your custom view and add it to your ViewController view. So it should look something like this:

    func createCustomView(){

    customView = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: 0))
    customView.something = something

    self.view.addSubview(customView)

}

do it in viewDidLoad() and everything should be ok