How to access views created in viewDivLoad - ios

Question

class ViewController: UIViewController
{
#IBAction func button_down(_ sender: Any)
{
do_something(view: myView);
}
override func viewDidLoad()
{
super.viewDidLoad();
let screen_size: CGRect = UIScreen.main.bounds;
var myView = UIView(frame: CGRect(x: 0, y: screen_size.height/2 - screen_size.width/2, width: screen_size.width, height: screen_size.width));
myView.backgroundColor = UIColor.red;
self.view.addSubview(myView);
}
}
When I try to compile this code, I get an error:
Use of unresolved identifier 'myView'
How can I solve this problem? I have tried declaring myView outside of viewDivLoad, but that's not permitted.

Answer 1

You should definitely do some research on the concept of "scope" in computer programming - it'll be difficult to go too far without it. myView only exists within the scope of viewDidLoad. If you want it to be available outside of that, you can make it a property of the class like so:
class ViewController: UIViewController
{
var myView: UIView!
#IBAction func buttonDown(_ sender: Any)
{
doSomething(view: myView)
}
override func viewDidLoad()
{
super.viewDidLoad()
let screenSize: CGRect = UIScreen.main.bounds
myView = UIView(frame: CGRect(x: 0, y: screenSize.height/2 - screenSize.width/2, width: screenSize.width, height: screenSize.width))
myView.backgroundColor = UIColor.red
self.view.addSubview(myView)
}
}
A couple of other notes:
You don't need semicolons at the end of lines in Swift.
It seems you're using Interface Builder, so I would suggest creating myView that way instead of programmatically.
Function and variable names in Swift should be camel cased - so buttonDown instead of button_down, screenSize instead of screen_size.