不确定我是否遇到了WebKit中的错误或者我正在做一些可怕的错误,但我无法弄清楚如何使用WKScriptMessageHandler而不会导致WKScriptMessage.body中包含的任何值泄漏.
我能够组建一个最小的Mac项目来隔离问题,但无济于事.
在主视图控制器中：
class ViewController: NSViewController {
var webView: WKWebView?
override func viewDidLoad() {
super.viewDidLoad()
let userContentController = WKUserContentController()
userContentController.addScriptMessageHandler(self,name: "handler")
let configuration = WKWebViewConfiguration()
configuration.userContentController = userContentController
webView = WKWebView(frame: CGRectZero,configuration: configuration)
view.addSubview(webView!)
let path = NSBundle.mainBundle().pathForResource("index",ofType: "html")
let url = NSURL(fileURLWithPath: path!)!
webView?.loadRequest(NSURLRequest(URL: url))
}
}
extension ViewController: WKScriptMessageHandler {
func userContentController(userContentController: WKUserContentController,didReceiveScriptMessage message: WKScriptMessage) {
print(message.body)
}
}
然后在index.html文件中：
<html>
<head></head>
<body>
<script type="text/javascript">
webkit.messageHandlers.handler.postMessage("Here's a random number for you: " + Math.random() * 10)
</script>
</body>
</html>
当我运行项目然后在Instruments中打开内存调试器时,我看到以下泄漏：
如果我添加一个重新加载请求的按钮,并且这样做了几十次,那么应用程序的内存占用量会不断增长,并在达到某个阈值后崩溃.在这个最小的例子中崩溃可能需要一段时间,但在我的应用程序中,我每秒收到几条消息,崩溃所需的时间不到10秒.
整个项目可以是downloaded here.
知道发生了什么事吗？
解决方法
您所看到的是WebKit错误：
https://bugs.webkit.org/show_bug.cgi?id=136140.它是
fixed in WebKit trunk a while ago,但似乎没有合并到任何WebKit更新中.
您可以通过向WKScriptMessage添加-dealloc来解决此问题,以补偿过度保留.它可能看起来像这样：
//
// WKScriptMessage+WKScriptMessageLeakFix.m
// TestWebkitMessages
//
// Created by Mark Rowe on 6/27/15.
// Copyright © Mark Rowe.
//
// Permission is hereby granted,free of charge,to any person obtaining a copy of this software and
// associated documentation files (the "Software"),to deal in the Software without restriction,// including without limitation the rights to use,copy,modify,merge,publish,distribute,sublicense,// and/or sell copies of the Software,and to permit persons to whom the Software is furnished to do so,// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial
// portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS",WITHOUT WARRANTY OF ANY KIND,EXPRESS OR IMPLIED,INCLUDING BUT NOT
// LIMITED TO THE WARRANTIES OF MERCHANTABILITY,FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,DAMAGES OR OTHER LIABILITY,// WHETHER IN AN ACTION OF CONTRACT,TORT OR OTHERWISE,ARISING FROM,OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#import <mach-o/dyld.h>
#import <objc/runtime.h>
#import <WebKit/WebKit.h>
// Work around <https://webkit.org/b/136140> WKScriptMessage leaks its body
@interface WKScriptMessage (WKScriptMessageLeakFix)
@end
@implementation WKScriptMessage (WKScriptMessageLeakFix)
+ (void)load
{
// <https://webkit.org/b/136140> was fixed in WebKit trunk prior to the first v601 build being released.
// Enable the workaround in WebKit versions < 601. In the unlikely event that the fix is backported,this
// version check will need to be updated.
int32_t version = NSVersionOfRunTimeLibrary("WebKit");
int32_t majorVersion = version >> 16;
if (majorVersion > 600)
return;
// Add our -dealloc to WKScriptMessage. If -[WKScriptMessage dealloc] already existed
// we'd need to swap implementations instead.
Method fixedDealloc = class_getInstanceMethod(self,@selector(fixedDealloc));
IMP fixedDeallocIMP = method_getImplementation(fixedDealloc);
class_addMethod(self,@selector(dealloc),fixedDeallocIMP,method_getTypeEncoding(fixedDealloc));
}
- (void)fixedDealloc
{
// Compensate for the over-retain in -[WKScriptMessage _initWithBody:webView:frameInfo:name:].
[self.body release];
// Call our WKScriptMessage's superclass -dealloc implementation.
[super dealloc];
}
@end
将它放在项目的Objective-C文件中,将此文件的编译器标志设置为包含-fno-objc-arc,它应该为您处理泄漏.
