如何在iPhone屏幕中间显示活动指示灯？

Question

当我们绘制图像时,我们想要显示活动指示器.有人可以帮助我们吗？

Answer 1

UIActivityIndicatorView *activityView = [[UIActivityIndicatorView alloc]     
        initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];

    activityView.center=self.view.center;
    [activityView startAnimating];
    [self.view addSubview:activityView];

Answer 2

如果您使用的是Swift,这就是您的操作方法

let activityView = UIActivityIndicatorView(activityIndicatorStyle: .whiteLarge)
activityView.center = self.view.center
activityView.startAnimating()

self.view.addSubview(activityView)

Answer 3

代码已更新为Swift 3

SWIFT代码

import UIKit
class ViewController: UIViewController {

    let activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: UIActivityIndicatorViewStyle.whiteLarge)

    @IBOutlet weak var myBlueSubview: UIView!

    @IBAction func showButtonTapped(sender: UIButton) {
        activityIndicator.startAnimating()
    }

    @IBAction func hideButtonTapped(sender: UIButton) {
        activityIndicator.stopAnimating()
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        // set up activity indicator
        activityIndicator.center = CGPoint(x: myBlueSubview.bounds.size.width/2, y: myBlueSubview.bounds.size.height/2)
        activityIndicator.color = UIColor.yellow
        myBlueSubview.addSubview(activityIndicator)
    }
}

笔记

• 您可以将活动指示器置于屏幕中间,方法是将其作为子视图添加到根目录view而不是myBlueSubview.

  activityIndicator.center =  CGPoint(x: self.view.bounds.size.width/2, y: self.view.bounds.size.height/2)
  self.view.addSubview(activityIndicator)
  

• 您也可以UIActivityIndicatorView在Interface Builder中创建它.只需将活动指示器视图拖到故事板上并设置属性即可.务必检查隐藏时的隐藏.使用插座呼叫startAnimating()和stopAnimating().请参阅本教程.

• 请记住,LargeWhite样式的默认颜色为白色.因此,如果您有白色背景,则无法看到它,只需将颜色更改为黑色或任何其他颜色即可.

  activityIndicator.color = UIColor.black
  

• 一个常见的用例是运行后台任务.这是一个例子:

  // start animating before the background task starts
  activityIndicator.startAnimating()
  
  // background task
  DispatchQueue.global(qos: .userInitiated).async {
  
      doSomethingThatTakesALongTime()
  
      // return to the main thread
      DispatchQueue.main.async {
  
          // stop animating now that background task is finished
          self.activityIndicator.stopAnimating()
      }
  }
  

Answer 4

这是正确的方法:

UIActivityIndicatorView *activityIndicator = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
activityIndicator.center = CGPointMake(self.view.frame.size.width / 2.0, self.view.frame.size.height / 2.0);
[self.view addSubview: activityIndicator];

[activityIndicator startAnimating];

[activityIndicator release];

如果支持旋转,请设置自动调整遮罩.干杯!!!

Answer 5

Swift 4，自动布局版本

func showActivityIndicator(on parentView: UIView) {
    let activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: .gray)
    activityIndicator.startAnimating()
    activityIndicator.translatesAutoresizingMaskIntoConstraints = false

    parentView.addSubview(activityIndicator)

    NSLayoutConstraint.activate([
        activityIndicator.centerXAnchor.constraint(equalTo: parentView.centerXAnchor),
        activityIndicator.centerYAnchor.constraint(equalTo: parentView.centerYAnchor),
    ])
}