iOS-懒加载、单例、范型

iOS-懒加载

private lazy var activityIndicator: UIActivityIndicatorView = {
        let activity = UIActivityIndicatorView(style: UIActivityIndicatorView.Style.large)
        activity.color = UIColor.black
        return activity
    }()

iOS- 单例

static var share: HudView = HudView()

iOS- 范型

func beginHud<T: UIView>(T: T) {
        self.T = T
        T.addSubview(activityIndicator)
        activityIndicator.center = UIApplication.shared.windows.first?.center ?? T.center 
        activityIndicator.startAnimating()
    }