更改iOS应用程序中UIRefreshControl指示灯的初始位置

我正在开发带有UITableView和UIRefreshControl的iOS应用程序

我想将UIRefreshControl指示器的初始位置从默认值向下更改50px。我写下下面的代码

但是，初始位置不变。它保持原来的位置

你能告诉我怎么解决这个问题吗

CGFloat customRefreshControlHeight = 50.0f;
CGFloat customRefreshControlWidth = 320.0f;
CGRect customRefreshControlFrame = CGRectMake(0.0f,
                                              customRefreshControlHeight,
                                              customRefreshControlWidth,
                                              customRefreshControlHeight);
UIRefreshControl *refreshControl = [[UIRefreshControl alloc] initWithFrame:customRefreshControlFrame];
refreshControl.tintColor = [UIColor blackColor];
[refreshControl addTarget:self action:@selector(onRefresh:) forControlEvents:UIControlEventValueChanged];
[self.tableView addSubview:refreshControl];

简单（快速）

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我的解决方案是使用带有重写框架属性的自定义

UIRefreshControl

类。以下代码适用于我的所有情况。您可以尝试通过应用transform来实现它，而无需进行转换。自iOS 11以来，在viewDidLayoutSubviews中设置帧不起作用

class OffsetableRefreshControl: UIRefreshControl {

  var offset: CGFloat = 64
  override var frame: CGRect {
    set {
      var rect = newValue
      rect.origin.y += offset
      super.frame = rect
    }
    get {
      return super.frame
    }
  }

}

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直接设置框架不起作用，但您仍然可以随时使用AutoLayout放置refreshControl。只是别忘了将

翻译自动调整大小GMaskintoConstraints

设置为

false

例如，这个代码将刷新控制设置在屏幕中间。

let refreshControl = UIRefreshControl()
collectionView.refreshControl = refreshControl
refreshControl.translatesAutoresizingMaskIntoConstraints = false

NSLayoutConstraint(item: refreshControl, attribute: .centerX, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1.0, constant: 0).isActive = true
NSLayoutConstraint(item: refreshControl, attribute: .centerY, relatedBy: .equal, toItem: view, attribute: .centerY, multiplier: 1.0, constant: 0).isActive = true

---

我想你可以在这里找到一个合适的答案：

let refreshControl = UIRefreshControl()
collectionView.refreshControl = refreshControl
refreshControl.translatesAutoresizingMaskIntoConstraints = false

NSLayoutConstraint(item: refreshControl, attribute: .centerX, relatedBy: .equal, toItem: view, attribute: .centerX, multiplier: 1.0, constant: 0).isActive = true
NSLayoutConstraint(item: refreshControl, attribute: .centerY, relatedBy: .equal, toItem: view, attribute: .centerY, multiplier: 1.0, constant: 0).isActive = true