Swift - Retrieving subviews

问题

In my application I am adding labels to the view and then I am attempting to clear particular labels from the view when a button is clicked and am running into an error when trying to retrieve the subviews:

class FirstViewController: UIViewController {

     @IBAction func btnAddTask_Click(sender: UIButton){

          var subViews = self.subviews.copy()

    }
 }

I get the error:

'FirstViewController' does not have a member named 'subviews'

How can I get the subviews of the current view?

回答1:

UIViewController doesn't have a subviews property. It has a view property, which has a subviews property:

for subview in self.view.subviews {
   // Manipulate the view
}

But typically this is not a good idea. You should instead put the labels you want into an IBOutletCollection and iterate over that. Otherwise you've very tied to the exact set of subviews (which may change).

To create the IBOutletCollection, select all the labels you want in IB, and control-drag them to the source code. It should ask if you want to make a collection array. (Note that there is no promise on the order of this array.)

回答2:

For find all subviews from your view you can use this code:

for subview in self.view.subviews {
   // Use your subview as you want
}

But for use it, you must identify view what you need. You can mark any element, what you create, with special Identifier like this:

myButton.restorationIdentifier = "mySpecialButton";

And after that you can find your element use this structure:

for view in view.subviews {
                if (view.restorationIdentifier == "mySpecialButton") {
                    print("I FIND IT");
                    view.removeFromSuperview();
                }
            }

回答3:

Hacky elegance:

Get the position of the click.
Retrieve the view with hitTest.
Differentiate the view with accessibilityIdentifier.

accessibilityIdentifier is developer facing and was intended for UI Automation.

Swift 4

@objc func handleTap(_ gestureRecognizer: UITapGestureRecognizer) {
    let positionInView = gestureRecognizer.location(in: view)
    let hitTestView = view?.hitTest(positionInView, with: nil)
    print("hitTestView: \(hitTestView?.accessibilityIdentifier)")
}

来源：https://stackoverflow.com/questions/26086175/swift-retrieving-subviews

标签

xcode

swift

subviews