Swift：在自定义类中启动和停止活动指示器的动画

Question

我想在自定义类中放置一个活动指示器，以便可以从任何视图控制器启动/停止它。

下面的代码在启动活动指示器时工作但不停止，我该怎么做？

static func activityIndicatorFunction(view: UIView, targetVC: UIViewController, animate: Bool) {

    var activityIndicator: UIActivityIndicatorView = UIActivityIndicatorView()

    if animate == false {
        activityIndicator.stopAnimating()
        UIApplication.shared.endIgnoringInteractionEvents()
    } else {
        activityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
        activityIndicator.backgroundColor = UIColor(red:0.16, green:0.17, blue:0.21, alpha:1)
        activityIndicator.layer.cornerRadius = 6
        activityIndicator.center = targetVC.view.center
        activityIndicator.hidesWhenStopped = true
        activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.whiteLarge
        view.addSubview(activityIndicator)
        activityIndicator.startAnimating()
        //UIApplication.shared.beginIgnoringInteractionEvents()
    }
}

启动活动指示器的示例，如果我想停止它，animate 参数将为 false。

Utils.activityIndicatorFunction(view: view, targetVC: self, animate: true)

Answer 1

这是协议扩展的理想选择。我最近自己做了这个。

首先在一个文件中创建协议，比如 ActivityIndi​​catorPresenter.swift

/// Used for ViewControllers that need to present an activity indicator when loading data.
public protocol ActivityIndicatorPresenter {
    
    /// The activity indicator
    var activityIndicator: UIActivityIndicatorView { get }
    
    /// Show the activity indicator in the view
    func showActivityIndicator()
    
    /// Hide the activity indicator in the view
    func hideActivityIndicator()
}

创建协议扩展（在同一个文件中……或不同的文件中）

public extension ActivityIndicatorPresenter where Self: UIViewController {
    
    func showActivityIndicator() {
        DispatchQueue.main.async {
            
            self.activityIndicator.activityIndicatorViewStyle = .whiteLarge
            self.activityIndicator.frame = CGRect(x: 0, y: 0, width: 80, height: 80) //or whatever size you would like
            self.activityIndicator.center = CGPoint(x: self.view.bounds.size.width / 2, y: self.view.bounds.height / 2)
            self.view.addSubview(self.activityIndicator)
            self.activityIndicator.startAnimating()
        }
    }
    
    func hideActivityIndicator() {
        DispatchQueue.main.async {
            self.activityIndicator.stopAnimating()
            self.activityIndicator.removeFromSuperview()
        }
    }
}

然后任何视图控制器都可以符合协议

class MyViewController: UIViewController, ActivityIndicatorPresenter {

/// Make sure to add the activity indicator
var activityIndicator = UIActivityIndicatorView()

//Suppose you want to load some data from the network in this view controller
override func viewDidLoad() {
    super.viewDidLoad()
    showActivityIndicator() //Wow you can use this here!!!
    getSomeData { data in 
        //do stuff with data
        self.hideActivityIndicator()
    }
}

Answer 2

我的建议是将它们实现为两个独立的方法，同时将它们添加到UIViewController的扩展中，如下：

UIViewController 扩展：

extension UIViewController {
    func showActivityIndicator() {
        let activityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
        activityIndicator.backgroundColor = UIColor(red:0.16, green:0.17, blue:0.21, alpha:1)
        activityIndicator.layer.cornerRadius = 6
        activityIndicator.center = view.center
        activityIndicator.hidesWhenStopped = true
        activityIndicator.activityIndicatorViewStyle = .WhiteLarge
        activityIndicator.startAnimating()
        //UIApplication.shared.beginIgnoringInteractionEvents()

        activityIndicator.tag = 100 // 100 for example

        // before adding it, you need to check if it is already has been added:
        for subview in view.subviews {
            if subview.tag == 100 {
                print("already added")
                return
            }
        }

        view.addSubview(activityIndicator)
    }

    func hideActivityIndicator() {
        let activityIndicator = view.viewWithTag(100) as? UIActivityIndicatorView
        activityIndicator?.stopAnimating()

        // I think you forgot to remove it?
        activityIndicator?.removeFromSuperview()

        //UIApplication.shared.endIgnoringInteractionEvents()
    }
}

我假设您希望始终将activityIndicator 显示/隐藏到ViewController.view，如果不是，您可能需要让它成为UIView 的activityIndi​​cator 而不是UIViewController。 em>

用法：

例如，假设您有两个 IBAction，第一个显示活动指示器，另一个隐藏它，它们应该是这样的：

@IBAction func show(sender: AnyObject) {
    showActivityIndicator()
}

@IBAction func hide(sender: AnyObject) {
    hideActivityIndicator()
}

Answer 3

我发现最好为活动指示器设置一个“标签”，然后在停止动画时引用它，使用一个功能隐藏和一个显示，如 Ahmad 建议的那样。 Ahmad F 的回答和 Guillermo 的回答似乎也不错。

在我的 Utils.swift 文件中显示/隐藏函数：

static func showActivityIndicator(view: UIView, targetVC: UIViewController) {

    var activityIndicator: UIActivityIndicatorView = UIActivityIndicatorView()

    activityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
    activityIndicator.backgroundColor = UIColor(red:0.16, green:0.17, blue:0.21, alpha:1)
    activityIndicator.layer.cornerRadius = 6
    activityIndicator.center = targetVC.view.center
    activityIndicator.hidesWhenStopped = true
    activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.whiteLarge
    activityIndicator.tag = 1
    view.addSubview(activityIndicator)
    activityIndicator.startAnimating()
    UIApplication.shared.beginIgnoringInteractionEvents()
}

static func hideActivityIndicator(view: UIView) {
    let activityIndicator = view.viewWithTag(1) as? UIActivityIndicatorView
    activityIndicator?.stopAnimating()
    activityIndicator?.removeFromSuperview()
    UIApplication.shared.endIgnoringInteractionEvents()
}

调用显示功能：

Utils.showActivityIndicator(view: view, targetVC: self)

调用隐藏函数：

Utils.hideActivityIndicator(view: view)