ios - 事件指示器不在TableView中居中

我想用activity indicator文件在TableView中显示NIB/XIB，但它不在中间，而是放在右侧
我愿意：

override func viewDidLoad() {
    super.viewDidLoad()

let actInd: UIActivityIndicatorView = UIActivityIndicatorView()
    actInd.frame = CGRect(x: 0.0, y: 0.0, width: 40.0, height: 40.0)
    actInd.center = self.view.center
    actInd.hidesWhenStopped = true
    actInd.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.whiteLarge
    self.view.addSubview(actInd)
    actInd.startAnimating()
}

最佳答案

let actInd: UIActivityIndicatorView = UIActivityIndicatorView()

override func viewDidLoad() {
    super.viewDidLoad()

    actInd.frame = CGRect(x: 0.0, y: 0.0, width: 40.0, height: 40.0)
    actInd.hidesWhenStopped = true
    actInd.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.whiteLarge
    self.view.addSubview(actInd)
    actInd.startAnimating()
}


override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    actInd.center = self.view.center
}

/* Following two functions are acceptable also.
override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    actInd.center = self.view.center
}

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    actInd.center = self.view.center
}
*/