没办法在iOS 9 beta / 9.3上更改WKWebView的滚动速率
问题说明
在iOS 8上，下面的代码工作正常，它可以更惯性地滚动。
On iOS 8, the below code works fine, it can scroll with more inertia.
webView.scrollView.decelerationRate = UIScrollViewDecelerationRateNormal;
对于iOS 9 beta 3，即使没有错误，此代码也毫无意义。
这是一个错误还是还有其他方法吗？
As for iOS 9 beta 3, this code is meaningless, even without an error.
Is this a bug or are there any other ways around?
注意：UIWebView的滚动速率可以在两个版本上更改两种类型。
Note: UIWebView's scroll rate can be changed two types on both versions.
正确答案
更新：这已经修复但未在iOS 9.3中部署（请参阅下面的解决方法）。更多细节：
Update: this has been fixed but not deployed in iOS 9.3 (see workaround below). More detail here:
- https://bugs.webkit.org/show_bug.cgi?id=148086
- http://trac.webkit.org/changeset/188541/trunk/Source/WebKit2/UIProcess/ios/WKScrollView.mm
我有同样的问题，似乎是iOS 9中的一个错误。
I had the same issue and it seems to be a bug in iOS 9.
解决方法是在将开始拖动委托而不是在实例化时设置它：
The workaround is to set it in the will begin dragging delegate instead of at the time of instantiation:
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
scrollView.decelerationRate = UIScrollViewDecelerationRateNormal;
}
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