WKWebKit未附加到视图层次结构时执行javascript [英] WKWebKit javascript execution when not attached to a view hierarchy
问题描述
我想从 UIWebView 切换到 WKWebView 。在我的代码中，Web视图实例是在屏幕外创建的（不附加到视图层次结构）并且加载了URL。加载完成后，Web视图将在单独的UIWindow（如插页式广告）中呈现给用户。使用 UIWebView ，一切正常;但是在切换到 WKWebView 之后，角度javascript代码以一种意想不到的方式运行。
I want to switch to WKWebView from UIWebView. In my code, the web view instance is created offscreen (without attaching to the view hierarchy) and URL is loaded. When loading is done, the web view is presented to the user in a separate UIWindow (like an interstitial ad). Everything works fine with UIWebView; but after switching to WKWebView, the angular javascript code behaves in an unexpected way.
在做了一些研究后，我当 WKWebView 实例没有附加到视图层次结构时，我们发现javascript计时器（和HTTP加载器）被暂停：如果你在javascript中启动一个以分离运行的计时器 WKWebView - 在附加Web视图之前不会触发它。
After doing some research, I've figured out that javascript timers (and HTTP loaders) are suspended when the WKWebView instance is not attached to the view hierarchy: if you start a timer in javascript which runs in detached WKWebView - it won't be fired until the web view is attached.
任何人都可以建议可能的解决方法（除了将隐藏的Web视图附加到关键窗口然后将其移动到另一个窗口）？
Can anyone suggest a possible workaround (besides attaching a hidden web view to the key window and then moving it to another window)?
我已经创建了一个示例项目来演示该问题（或者更可能，一个WebKit功能）
I've created a sample project to demonstrate the issue (or, more likely, a WebKit feature)
https://dl.dropboxusercontent.com/u/148568148/WebKitViewTest.zip
测试应用程序加载一个带有javascript的网页，用于安排计时器和加载HT TP请求。您可以使用开关来显示/隐藏Web视图（设置'隐藏'属性）并将其从视图层次结构中附加/分离。
The test application loads a web page with javascript which schedules a timer and loads HTTP request. You can use switches to show/hide web view (sets 'hidden' property) and attach/detach it from the view hierarchy.
如果附加了Web视图（隐藏或可见）并且你点击加载，javascript工作正常：你可以看到成功或失败警告对话框。如果它已经分离 - 计时器只会在它附加到视图层次结构时触发（将Detached切换为on，点击Load，等待几秒钟并切换回off）。您还可以从Safari Web Inspector中检查 console.log 。
If the web view is attached (hidden or visible) and you hit Load, the javascript works fine: you can see success or failure alert dialog. If it's detached - the timer will only fire when it's attached to the view hierarchy (switch "Detached" to "on", hit "Load", wait a couple of seconds and switch back to "off"). You can also check console.log from Safari Web Inspector.
以下是测试网页来源：
<!doctype html>
<html ng-app="project">
<head>
<script
src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.16/angular.js"></script>
<script src="project.js"></script>
</head>
<body>
<div id="simple" ng-controller="MyController" data-ng-init="callNotify(message);">
</div>
</body>
</html>
javascript：
And the javascript:
angular.
module('project', []).
controller('MyController', ['$scope','notify', function ($scope, notify) {
$scope.callNotify = function(msg) {
notify(msg);
};
}]).
factory('notify', ['$window', '$http', '$q', '$timeout', function(win, $http, $q, $timeout) {
return function(msg) {
deferred = $q.defer();
$timeout(function() {
$http.get('http://jsonplaceholder.typicode.com/posts').
success(function(data, status, headers, config) {
alert("success");
console.log("success")
}).
error(function(data, status, headers, config) {
alert("error");
console.log("error")
});
});
return deferred.promise;
};
}]);
推荐答案
遇到同样的问题，我从未发现任何问题除了将WKWebView添加到视图层次结构并使用AutoLayout将其移出屏幕外的解决方案。幸运的是，这种解决方法确实可靠。
Having run into the same problem, I never found any solution except to add the WKWebView to the view hierarchy and move it offscreen with AutoLayout. Fortunately, this workaround does work reliably.
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