等待视图类

如下是一个单例类的模式，你也可以是有其init方法创建新的view给单个view使用。

public extension DispatchQueue {
private static var onceToken = [String]()
public class func once(_ token: String, _ block:@escaping () -> Void) {
    objc_sync_enter(self)
    defer {
        objc_sync_exit(self)
    }
    if onceToken.contains(token) {
        return
    }
    onceToken.append(token)
    block()
}
}

final class WaitView: UIView {
static func shared() -> WaitView {//这里使用了GCD的单例类创建方法，可以使用更简便的方法
    struct Singleton {
        static var single = WaitView(frame: UIScreen.main.bounds)
    }
    DispatchQueue.once("WaitView") {
        Singleton.single = shared()
    }
    return Singleton.single
}

//static let share = WaitView()

var endBlock: (() -> Void)?

var contentView: UIActivityIndicatorView!

override init(frame: CGRect) {
    super.init(frame: frame)
    self.backgroundColor = UIColor(white: 0, alpha: 0.2)
    initActivity()
}

private func initActivity() {
    self.contentView = UIActivityIndicatorView(activityIndicatorStyle: UIActivityIndicatorViewStyle.whiteLarge)
    self.contentView.frame.size = CGSize(width: 50, height: 50)
    self.contentView.center = CGPoint(x: self.bounds.width / 2, y: self.bounds.height / 2)
    self.addSubview(contentView)
}

override func removeFromSuperview() {
    super.removeFromSuperview()
//        print("wait view removed!!!")
}

required init(coder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

deinit {
    print("wait view deinit!!!")
}

//菊花转动开始
func play()
{
    UIApplication.shared.keyWindow?.addSubview(self)
    self.contentView.startAnimating()
}

func playOn(_ view: UIView) {
    view.addSubview(self)
    self.contentView.startAnimating()
}

func playOn(_ viewController: UIViewController) {
    viewController.view.addSubview(self)
    self.contentView.startAnimating()
}

//菊花转动结束
func stop()
{
    if Wait.isExist() {
        self.contentView.stopAnimating()
        self.removeFromSuperview()
        self.endBlock?()
    }
}

func stoped() {
    self.contentView.stopAnimating()
    self.removeFromSuperview()
    self.endBlock?()
}

}

最后加上一个类，方便于使用该单例类

public class Wait {
public class func startAfter(_ time: TimeInterval) {
    DispatchQueue.main.asyncAfter(deadline: .now() + time, execute: {
        Wait.start()
    })
}

public class func start() {
    WaitView.shared().play()
}

public class func startDismiss(_ time: TimeInterval) {
    WaitView.shared().play()
    DispatchQueue.main.asyncAfter(deadline: .now() + time, execute: {
        WaitView.shared().stop()
    })
}

public class func stop() {
    WaitView.shared().stop()
}

public class func stop(_ endBlcok: (() -> Void)?) {
    WaitView.shared().stop()
    WaitView.shared().endBlock = {
        endBlcok?()
    }
}

public class func isExist() -> Bool {
    if let views = UIApplication.shared.keyWindow?.subviews {
        for view in views {
            if view.isKind(of: WaitView.self) {
                return true
            }
        }
    }
    
    return false
}

}