iOS11 WKWebView问题汇总

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我是靠谱客的博主粗心皮皮虾，这篇文章主要介绍iOS11 WKWebView问题汇总，现在分享给大家，希望可以做个参考。

问题一描述:

iOS9和iOS10用WKWebView加载URL都没有问题,iOS11却是一片空白
可能是用了NSMutableURLRequest,iOS11貌似不支持NSMutableURLRequest,无论是用UIWebView还是WKWebView,都不支持NSMutableURLRequest

解决方法参考

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if #available(iOS 11, *) {
   let request = NSURLRequest.init(url: URL.init(string: urlStr)!)
   self.wkWebView.load(request as URLRequest)
  }else{
   let request = NSMutableURLRequest.init(url: URL.init(string: urlStr)!, cachePolicy: NSURLRequest.CachePolicy.reloadIgnoringLocalAndRemoteCacheData, timeoutInterval: 60)
   request.httpMethod = "GET"
   request.httpBody = ("token=" + tokenValue()).data(using: String.Encoding.utf8)
   self.wkWebView.load(request as URLRequest)
  }

问题二描述：在用iPhone X 的模拟器进入Hybrid项目时，发现一进去就崩溃，崩溃信息少的可怜：

libc++abi.dylib: terminating with uncaught exception of type NSException

靠这玩意儿肯定是定位不出bug的，不过全局断点还是给出了一点信息：

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- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
 NSString *requestString = navigationAction.request.URL.absoluteString;
 //对外链、拨号和跳转appstore做特殊处理
 UIApplication *app = [UIApplication sharedApplication];
 NSURL *url = [navigationAction.request URL];
 //电话
 //此处省略若干业务代码
 if ([url.absoluteString containsString:@"itunes.apple.com"])
 {
  if ([app canOpenURL:url])
  {
   [app openURL:url];
   decisionHandler(WKNavigationActionPolicyCancel);
  }
 }
 if ([requestString hasPrefix:@"easy-js:"]) {
  [self handleRequestString:requestString webView:(EasyJSWebView *)webView.superview];
  decisionHandler(WKNavigationActionPolicyCancel);
 }
 if ([self.realDelegate respondsToSelector:@selector(webView:decidePolicyForNavigationAction:decisionHandler:)])
 {
  [self.realDelegate webView:webView decidePolicyForNavigationAction:navigationAction decisionHandler:decisionHandler];
 }
 decisionHandler(WKNavigationActionPolicyAllow);//崩在这里
}

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- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
 NSString *requestString = navigationAction.request.URL.absoluteString;
 //对外链、拨号和跳转appstore做特殊处理
 UIApplication *app = [UIApplication sharedApplication];
 NSURL *url = [navigationAction.request URL];
 //电话
 //此处省略若干业务代码
 if ([url.absoluteString containsString:@"itunes.apple.com"])
 {
  if ([app canOpenURL:url])
  {
   [app openURL:url];
   decisionHandler(WKNavigationActionPolicyCancel);
  }
 }
 if ([requestString hasPrefix:@"easy-js:"]) {
  [self handleRequestString:requestString webView:(EasyJSWebView *)webView.superview];
  decisionHandler(WKNavigationActionPolicyCancel);
 }
 if ([self.realDelegate respondsToSelector:@selector(webView:decidePolicyForNavigationAction:decisionHandler:)])
 {
  [self.realDelegate webView:webView decidePolicyForNavigationAction:navigationAction decisionHandler:decisionHandler];
 }
 decisionHandler(WKNavigationActionPolicyAllow);//崩在这里
}

仍然不知道为啥子崩在这儿？之前一直是没问题的啊？？

小Tips：
为了获取一些堆栈信息以便于快准狠的定位问题，可以在main函数里：

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int main(int argc, char * argv[]) {
 @try {
  @autoreleasepool
  {
   return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
  }
 }
 @catch (NSException* exception)
 {
  NSDebugLog(@"Exception=%@nStack Trace:%@", exception, [exception callStackSymbols]);
 }
}

最终得到一条关键报错：

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Completion handler passed to -[WKPrivateNavigationDelegate webView:decidePolicyForNavigationAction:decisionHandler:] was called more than once

意思就是WKWebView的这个代理方法被多次调用了。

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if ([requestString hasPrefix:@"easy-js:"]) {
  [self handleRequestString:requestString webView:(EasyJSWebView *)webView.superview];
  decisionHandler(WKNavigationActionPolicyCancel);
 }
 if ([self.realDelegate respondsToSelector:@selector(webView:decidePolicyForNavigationAction:decisionHandler:)])
 {
  [self.realDelegate webView:webView decidePolicyForNavigationAction:navigationAction decisionHandler:decisionHandler];
 }
 decisionHandler(WKNavigationActionPolicyAllow);//崩在这里

简单分析一下被多次调用的原因：

1、系统判断这个方法被多次执行，主要是看decisionHandler()是否被多次执行；
2、由于if判断里会执行decisionHandler()，最后一行代码也会执行decisionHandler()，并且self.realDelegate中也会执行decisionHandler()，这就导致了decisionHandler()这个handler可能会被多次执行。
那解决问题的方向就是修改代码保证WKWebView单次LoadRequest只调一次此代理方法～

修改如下：

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if ([requestString hasPrefix:@"easy-js:"]) {
  [self handleRequestString:requestString webView:(EasyJSWebView *)webView.superview];
  decisionHandler(WKNavigationActionPolicyCancel);
 }
 else if ([self.realDelegate respondsToSelector:@selector(webView:decidePolicyForNavigationAction:decisionHandler:)])
 {
  [self.realDelegate webView:webView decidePolicyForNavigationAction:navigationAction decisionHandler:decisionHandler];
 } else {
  decisionHandler(WKNavigationActionPolicyAllow);
 }

即保证了单次LoadRequest只执行一次decisionHandler()

问题三描述：iOS11 WKWebview获取高度不准确

遇见这个问题的时候，我发现偏离了大概64像素，由此联想到了tableView和collectionView。
故解决办法如下：

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if (@available(iOS 11.0, *)) {
  _webView.scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
  _webView.scrollView.contentInset = UIEdgeInsetsMake(0, 0, 0, 0);
  _webView.scrollView.scrollIndicatorInsets = _webView.scrollView.contentInset;
 }