ios - Swift - 单击按钮后立即显示带有加载指示器的警报的最佳方式？

Question

我尝试使用主线程来显示但它没有用，有没有想过为什么警报没有立即显示？

@IBAction func updateData(_ sender: Any) {
    let alert = UIAlertController(title: "Updating data", message: "Please wait...", preferredStyle: .alert)
    alert.view.tintColor = UIColor.black
    let loadingIndicator: UIActivityIndicatorView = UIActivityIndicatorView(frame: CGRect(x: 10,y: 5,width: 50, height: 50)) as UIActivityIndicatorView
    loadingIndicator.hidesWhenStopped = true
    loadingIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.gray
    loadingIndicator.startAnimating();

    alert.view.addSubview(loadingIndicator)
    DispatchQueue.main.async {
        self.present(alert, animated: true)

    }

Answer 1

UIAlertController 无法自定义，所以对我来说最好的解决方案是创建自定义 UIView XIB，然后在我需要的 ViewController 上实例化它。

XIB View 可能是这样的:

然后你创建一个 CustomAlertLoadingView.swift 文件，它是 UIView 的子类，将它关联到 XIB 并创建 IBOutlets。

要在任何 ViewController 中显示它，只需创建此扩展

extension UIViewController {
     func presentAlert(title: String) {
        let nib = UINib(nibName: "CustomAlertLoadingView", bundle: nil)
        let customAlert = nib.instantiate(withOwner: self, options: nil).first as! CustomAlertLoadingView

        customAlert.tag = 12345
        customAlert.titleAlertLabel.text = title
        customAlert.indicator.startAnimating()


        let screen = UIScreen.main.bounds
        customAlert.center = CGPoint(x: screen.midX, y: screen.midY)

        self.view.addSubview(customAlert)
    }
}

使用self.yourViewController.presentAlert(title:"yourTitle")

要关闭警报，请在 UIVIewController 扩展中创建此函数

func dismissCustomAlert() {
        if let view = self.view.viewWithTag(12345) {
            view.removeFromSuperview()
        }
}

然后调用self.yourViewController.dismissCustomAlert