ios - 刷新时的 UIWebView 网站向下移动 - Swift

Question

每当我在我的应用程序中使用的 UIWebView 中重新加载网站时，网站就会向下移动。我不知道为什么会这样，因为当我在 Safari 中访问网站的移动版本时，网站不会向下滚动。

下面是 UIWebView 的代码:

import Foundation
import UIKit
import SVProgressHUD
import Canvas

class WebViewHome: UIViewController, UIWebViewDelegate, SWRevealViewControllerDelegate{


@IBOutlet weak var heightConstraint: NSLayoutConstraint!
@IBOutlet weak var WebViewContainer: UIView!
@IBOutlet weak var WebViewTst: UIWebView!
@IBOutlet weak var animView: CSAnimationView!

override func viewDidLoad() {
    super.viewDidLoad()

    self.navigationController?.navigationBar.topItem!.title = "Home"

    let URL = NSURL(string: "https://gunnoracle.com/")
    WebViewTst.loadRequest(NSURLRequest(url: URL! as URL) as URLRequest)

    let topSpace = -190
    let bottomSpace = -3045
    let leftSpace = -40
    let rightSpace = -40
    WebViewTst.scrollView.contentInset = UIEdgeInsets(top: CGFloat(topSpace), left: CGFloat(leftSpace), bottom: CGFloat(bottomSpace), right: CGFloat(rightSpace))
    WebViewTst.scrollView.bounces = false

    WebViewTst.scrollView.maximumZoomScale = 1.0
    WebViewTst.scrollView.minimumZoomScale = 1.0

    WebViewTst.delegate = self



}

override func viewDidAppear(_ animated: Bool) {


    self.revealViewController().delegate = self

}

func revealController(_ revealController: SWRevealViewController!, didMoveTo position: FrontViewPosition) {

    if(revealController.frontViewPosition == FrontViewPosition.right){


        animView.isHidden = true


        UIView.animate(withDuration: 0.5, animations: {

            self.WebViewTst.layer.zPosition = 1
            self.WebViewTst.transform = CGAffineTransform(translationX: 0, y: -65);
            self.view.layoutIfNeeded()

        })

    }

}
func webView(_ webView: UIWebView, shouldStartLoadWith request: URLRequest, navigationType: UIWebViewNavigationType) -> Bool {

    switch navigationType {

    case .linkClicked:

        let topSpace = -170
        let bottomSpace = -2840
        let leftSpace = -40
        let rightSpace = -40

        animView.startCanvasAnimation()
        WebViewTst.scrollView.contentInset = UIEdgeInsets(top: CGFloat(topSpace), left: CGFloat(leftSpace), bottom: CGFloat(bottomSpace), right: CGFloat(rightSpace))
        WebViewTst.scrollView.bounces = false

        WebViewTst.scrollView.maximumZoomScale = 1.0
        WebViewTst.scrollView.minimumZoomScale = 1.0

        WebViewTst.delegate = self

    default:
        break
    }
    return true
}

func webViewDidStartLoad(_ webView: UIWebView) {

    SVProgressHUD.show(withStatus: "Loading...")
    SVProgressHUD.setDefaultStyle(SVProgressHUDStyle.dark)
    SVProgressHUD.setRingThickness(1.0)
    NSLog("Webview has started loading")
}

func webViewDidFinishLoad(_ webView: UIWebView) {
    SVProgressHUD.dismiss()
    NSLog("Webview has successfully loaded")
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

Answer 1

这是对问题下评论的跟进。

请注意，此代码未经测试，因此只能用作指南。

为了抵消顶部的内容插入并保持滚动位置，您可以使用类似于

的代码

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    CGFloat currentYOffset = scrollView.contentOffset.y;
    CGFloat topIntest = scrollView.contentInset.top;
    scrollView.contentOffset = CGPointMake(scrollView.contentOffset.x, currentYOffset - topIntest);
}

如果没有看到您的确切项目和预期的视觉输出，就很难给出完美的答案。

理想情况下，您应该以稍微不同的方式处理此解决方案。您上面的代码使用固定的 contentInset 告诉我您需要您的页面具有特定的填充才能看起来正确。为确保将性能保持在最高水平，您真正应该做的是在您正在加载的网页中实现该填充。

如果您可以访问网页源代码，请在 body 标签上使用 CSS 填充样式来复制您想要的间距/填充/对齐方式。

如果您无权访问网页源代码，您也可以使用以下方式将网页加载到字符串

NSString *content = [NSString stringWithContentsOfURL:@"http://example.com "encoding:NSUTF8StringEncoding error:nil];

然后您可以将自己的样式注入(inject) HTML。

有很多方法可以做到这一点，一个例子是:

    NSURL *contentURL = [NSURL URLWithString:@"http://example.com"];
    //load content to string
    NSString *content = [NSString stringWithContentsOfURL:contentURL encoding:NSUTF8StringEncoding error:nil];

    //create css style to inject
    NSString *paddingCSS = @"<style> body { margin-top: -190px; margin-left:-40px; margin-right:-40px; margin-bottom:-3045px } </style></head>";

    //inject the string just before the </head> tag
    [content stringByReplacingOccurrencesOfString:@"</head>" withString:paddingCSS options:NSCaseInsensitiveSearch range:NSRangeFromString(content)];

    //load the webview using the content string.
    //Set the baseURL to ensure relative links etc. still work
    [self.webView loadHTMLString:content baseURL:contentURL];