如何在 Swift for macOS 中迭代子视图并返回 object 类型

Question

After finding this question and answers , I thought I would try to reduce the size of my code considerably by looping through various objects in the view and set parameters.

I cannot use the tag value because I do not set tags, except in rare circumstances. I set plain language identifiers for all of my UI elements. I will use NSTextField as an example to try and set the delegate for each NSTextField in the view.

import Cocoa

class ViewController: NSViewController, NSTextFieldDelegate {

    @IBOutlet var myTextField1: NSTextField!
    // ... and many, many more NSTextFields ...

    override func viewDidLoad {
        super.viewDidLoad()

        let textFields = self.view.subviews.filter { $0.isKind(of: NSTextField.self) } 
        for textField in textFields {
            if textField.identifier!.rawValue[textField.identifier!.rawValue.startIndex] != "_" { // Avoiding Swift assigned identifiers
                textField.delegate = self
            }
        }
    }
}

I am being told that Value of type 'NSView' has no member 'delegate' , which makes sense because the NSView of the NSTextField is what is actually being placed into the list, not the actual NSTextField object.

Since IBOutlet Collections aren't available for macOS, I can't simply iterate through a collection to do what I want to do. At least as a far as I know of.

Answer 1

I assume the goal is to get textFields to have type [NSTextField].

Right now, you have filter with is (which doesn't change type)

let textFields = self.view.subviews.filter { $0.isKind(of: NSTextField.self) }

You should change this to compactMap with as? (which does change type).

let textFields = self.view.subviews.compactMap { $0 as? NSTextField }