Swift - 循环遍历不同的对象类型

Question

Current I do this to loop through all of my buttons:

for objects in view.subviews {
    if let object = objects as? UIButton {
        object.isEnabled = false
    }
}

Can I also include UIView and UILabel in this loop?

So instead of only objects as? UIButton objects as? UIButton , I want objects as? UIButton, UIView, UILabel objects as? UIButton, UIView, UILabel .

Answer 1

You could do it like this:

for objects in view.subviews {
    if let object = objects as? UIButton {
        object.isEnabled = false
    }
    if let object = objects as? UIView {
        object.isHidden = false
    }
    if let object = objects as? UILabel {
        object.isEnabled = false
    }
}

Answer 2

No, you can't set the isEnabled property of labels and other UIViews . Only objects that inherit from UIControl have the isEnabled property.

I would advise against looping through all a view's subviews and disabling all the controls. It is a very "shotgun" approach, and fragile.

A problem with it is that it won't work if you have any complexity to your view hierarchy. If you have buttons in a stack view, for example, your code would miss them. Or say they are in a table view. That won't work either.

Instead, I would suggest putting the outlets of the controls you want to disable into an array in your viewDidLoad() method. Then when you want to disable them all, loop through that array and set isEnabled to false for each.

Answer 3

An alternative is to assign tags to the relevant UI elements.

In the loop (or forEach closure) check if the tag is in the required range and conditional downcast the view to UIControl

view.subviews.forEach{ subView in
    guard (100...105).contains(subView.tag) else { return }
    (subView as? UIControl)?.isEnabled = false
}