Vertical scrolling in iOS not smooth

Question

I\'ve been searching far and wide through documentation regarding -webkit-overflow-scrolling: touch;, but I can only get it to work partially for my

Answer 1

I'm using WKWebView on an iPhone, iOS 12. I got no help with -webkit-overflow-scrolling:touch; But, I was able to implement a smooth scroll using a WKUIDelegate method for intercepting alert() calls. Instead of performing the alert(), I set the scrollView's contentOffset to a position value that's sent via the alert().

// in HtmlTable_VC.m
- (void)viewDidLoad
{
    [super viewDidLoad];

    wKWebView.scrollView.decelerationRate = UIScrollViewDecelerationRateFast;
    // go figure -- faster deceleration seems to slow the scrolling rate
    wKWebView.UIDelegate = self; // WKUIDelegate

    // ...

    NSString *htmlText = @"Your HTML page text here";
    [wKWebView loadHTMLString:htmlText baseURL:[NSBundle mainBundle].bundleURL];
}

// WKUIDelegate
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message
initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler
{
    // if the message is numeric, smooth scroll the wkWebView
    CGPoint scrollPoint = CGPointMake(0, [message intValue]);
    [self->wKWebView.scrollView setContentOffset:scrollPoint animated:YES];
    completionHandler();

    // if not numeric, it was a real alert() interception, can process here
}

And the HTML file (Help.html):

    



Your HTML here
 Stuff1 
 Stuff2 
...
 Go to Stuff1
 Go to Stuff2
...