UIWebDocumentView _updateSubviewCaches在iOS10中崩溃

2019年7月28日 140次阅读

我在iOS10中更严重地在HockeyApp中遇到以下崩溃.请查看下面给出的崩溃日志.

线程4崩溃：

0 libobjc.A.dylib 0x0000000187242f30 objc_msgSend + 16
1 UIKit 0x000000018e86e914 -[UIWebDocumentView _updateSubviewCaches] + 36
2 UIKit 0x000000018e69093c -[UIWebDocumentView subviews] + 88
3 UIKit 0x000000018e941bd4 -[UIView(CALayerDelegate) _wantsReapplicationOfAutoLayoutWithLayoutDirtyOnEntry:] + 68
4 UIKit 0x000000018e63d770 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1248
5 QuartzCore 0x000000018bb0640c -[CALayer layoutSublayers] + 144
6 QuartzCore 0x000000018bafb0e8 CA::Layer::layout_if_needed(CA::Transaction*) + 288
7 QuartzCore 0x000000018bafafa8 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 28
8 QuartzCore 0x000000018ba77c64 CA::Context::commit_transaction(CA::Transaction*) + 248
9 QuartzCore 0x000000018ba9f0d0 CA::Transaction::commit() + 508
10 QuartzCore 0x000000018ba9faf0 CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 116
11 CoreFoundation 0x00000001887a57dc __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 28
12 CoreFoundation 0x00000001887a340c __CFRunLoopDoObservers + 368
13 CoreFoundation 0x00000001886d2068 CFRunLoopRunSpecific + 472
14 WebCore 0x000000018d273a2c RunWebThread(void*) + 452
15 libsystem_pthread.dylib 0x000000018788b860 _pthread_body + 236
16 libsystem_pthread.dylib 0x000000018788b770 _pthread_start + 280
17 libsystem_pthread.dylib 0x0000000187888dbc thread_start + 0

知道这里发生了什么吗？
似乎以下崩溃组也是相关的.

碰撞组1

[UIWebBrowserView _collectAdditionalSubviews]
objc_msgSend() selector name: autorelease

碰撞组2

[UIWebDocumentView subviews]
objc_msgSend() selector name: arrayByAddingObjectsFromArray:

最佳答案 我正在回答我自己的问题,因为我能够复制这个问题并找到根本原因.

请注意以下事项.

1.我正在使用UIWebView.首先,不建议这样做.

2.以下实施方式会导致此问题.我在这里编写伪代码来演示这个问题.

@implementation MyViewController

    - (void)loadView {

        //creating UIWebView Here
        self.webView = [[UIWebView alloc] initWithFrame:_some_frame];

        //setting the web view properties here.

        //Adding to the view
        [self.view addSubView: self.webView];

        [self populateWebView];
    }

    - (void) populateWebView {
        [self.webView loadHTMLString:_some_html 
                             baseURL:[NSURL fileURLWithPath:_some_path]];
    }


    - (void)viewDidLayoutSubviews {
        [super viewDidLayoutSubviews];

        if (self.webView) {
           //The following two lines causing this issue.
           self.webView.scrollView.contentInset = _some_insets;
           self.webView.scrollView.scrollIndicatorInsets = _some_insets;
        }
    }

@end

3.解决方案如下.

@implementation MyViewController

    - (void)loadView {

        //creating UIWebView Here
        self.webView = [[UIWebView alloc] initWithFrame:_some_frame];

        //setting the web view properties here.

        //Adding to the view
        [self.view addSubView: self.webView];

        [self populateWebView];
    }

    - (void) populateWebView {
        [self.webView loadHTMLString:_some_html 
                             baseURL:[NSURL fileURLWithPath:_some_path]];
    }


    - (void)viewDidLayoutSubviews {
        [super viewDidLayoutSubviews];
    }

    - (void)webViewDidFinishLoad:(UIWebView *)webView {
        webView.scrollView.contentInset = _some_insets;
        webView.scrollView.scrollIndicatorInsets = _some_insets;
    }

@end

在我的实际代码中,我通过子类化UIWebView在这里使用自定义WebView类.不认为会产生一些问题.根本原因是在viewDidLayoutSubviews中设置“contentInset”和“scrollIndicatorInsets”,这不是一个好主意.当我把断点,“viewDidLayoutSubviews”调用几次,最终App崩溃.

作为一种解决方案,我将以下部分代码移动到“webViewDidFinishLoad”中,只有在完成加载后WebView准备就绪时才会调用它.因此,在此委托方法下添加此代码是有意义的.

webView.scrollView.contentInset = _some_insets;
webView.scrollView.scrollIndicatorInsets = _some_insets;
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