Swift 结合问题与 UILabel 订阅

Question

import UIKit
import Combine

class ViewController: UIViewController {

    @IBOutlet weak var allowMessageSwitch: UISwitch!
    @IBOutlet weak var sendButton: UIButton!
    @IBOutlet weak var messageLabel: UILabel!

    @Published var canSendMessages: Bool = false
    @Published var newMsg: String = ""

    private var switchSubscriber: AnyCancellable?
    private var btnSubscriber: AnyCancellable?


    override func viewDidLoad() {
        allowMessageSwitch.isOn = false
        super.viewDidLoad()
        setupProcesscingChain()
    }

    func setupProcesscingChain() {
        switchSubscriber = $canSendMessages.receive(on: DispatchQueue.main).assign(to: \.isEnabled, on: sendButton)

        btnSubscriber = $newMsg.receive(on: DispatchQueue.main).assign(to: \.text, on: messageLabel)
    }

    @IBAction func didSwitch (_ sender: UISwitch) {
        canSendMessages = sender.isOn
    }

    @IBAction func sendMessage( _ sender: Any) {
    }


}

我在

中遇到错误

btnSubscriber = $newMsg.receive(on: DispatchQueue.main).assign(to: \.text, on: messageLabel)

错误消息是

Type of expression is ambiguous without more context

我不明白为什么标签不能用作切换器 (bool)

我猜是因为 \.isEnabled 不是可选的，而 \.text 是可选的..??

我怎样才能使它以相同的格式工作。这是为了练习和了解 Combine 的工作原理。请帮忙！

Answer 1

lableSubscriber = $newMsg.receive(on: DispatchQueue.main).assign(to: \.text!, on: messageLabel)

我自己解决了！这很简单。只需强制打开 keyPath。

Swift 结合问题与 UILabel 订阅

Swift Combine question with UILabel subscribe

swift

combine