// MARK: - 初始化 UIActivityIndicatorView 加载视图
func setupActivity() {
//加载
let spinner = UIActivityIndicatorView()
spinner.activityIndicatorViewStyle = .gray
spinner.center = view.center
spinner.hidesWhenStopped = true
view.addSubview(spinner)
self.spinner = spinner
//开始刷新
spinner.startAnimating()
}
//加载数据完成时，结束刷新
self.spinner.stopAnimating()
