获取 UIScrollView contentView 的高度

Posted 2023-02-23

【中文标题】获取 UIScrollView contentView 的高度

【英文标题】：get height of UIScrollView contentView

【发布时间】：2016-04-02 01:11:24

【问题描述】：

我有一个UIViewController，它具有以下层次结构（及其NSLayoutConstraints）：

UIView
-UIScrollView
--UIView-ContentView (zero margins to the UIScrollview and equal height to UIScrollVIew's parent; mentioned in the code as self.contentView)
---UIView (fixed height, 0 top margin to Content View)
---UIView (fixed height, 0 top margin to above view)
---UIView (fixed height, 0 top margin to above view)
---UIView (fixed height, 0 top margin to above view)
---UIWebView (fixed height & linked to IBOutlet in the class; gets expanded)
---UILabel (top margin to UIWebView)
---UIView (fixed height, top margin to above label)
---UIView (fixed height, 0 top margin to above view)
---UIView (fixed height, 0 top margin to above view)
---UIView (fixed height, 0 top margin to above view)
---UIButton (fixed height, top margin to above view)

Scenario:
1. On viewDidLoad() I'm adding the html text by appending the javascript code that returns the height of the UIWebView
2. on UIWebViewDelegate method (shouldStartLoadWithRequest) I'm setting the following things:
- webViewHeight.constant (NSLayoutConstraint, linked from IB)
- self.scrollView.contentSize = CGSizeMake(self.view.frame.width, CGRectGetHeight(self.contentView.frame))


override func viewDidLoad() 
    self.webView.scrollView.scrollEnabled = false

    let heightHackScript = "<script type='text/javascript'>window.onload = function()  window.location.href = 'ready://' + document.body.offsetHeight; </script>"

        if let cBody:NSData = self.model?.text_content 

          self.webView.loadHTMLString(heightHackScript + String(data: cBody, encoding: NSUTF8StringEncoding)!, baseURL: nil)
        
  


func webView(webView: UIWebView, shouldStartLoadWithRequest request: NSURLRequest, navigationType: UIWebViewNavigationType) -> Bool 

  let url = request.URL

  if navigationType == .Other 
    if url?.scheme == "ready" 
      webViewHeight.constant = (url?.host?.floatValue)!
      self.scrollView.contentSize = CGSizeMake(self.view.frame.width, CGRectGetHeight(self.contentView.frame))
      return false
    
  
  return true

问题是CGRectGetHeight(self.contentView.frame) 没有获得所需的高度。有什么想法吗？

所以我想在将 HTML 加载到 UIWebView 后获得视图约束的高度。

【参考方案1】：

尝试调整 Web 视图的大小以适应其内容时遇到的难题是，Web 视图本身并不知道其中显示的 DOM 内容可能有多高。你要做的就是通过 JavaScript 询问 DOM 它的内容有多高。在我们的代码中，我们这样做：

[webView stringByEvaluatingJavaScriptFromString: @"document.height"]

或在 Swift 中：

webView.stringByEvaluatingJavaScriptFromString("document.height")

并使用结果值为我们的 UIWebView 选择大小。

【讨论】：

谢谢，但我想得到的是UIView-ContentView (zero margins to the UIScrollview and equal height to UIScrollVIew's parent; mentioned in the code as self.contentView) 的总高度，根据这个高度我会更新 UIScrollView 的高度 ContentSize。