ios - 带有 EKEventStoreChanged 通知的 NotificationCenter 使用不同的通知多次调用
<p><p>首先请注意，我没有像其他各种问题中所述那样多次注册为观察员。</p>
<p>当我在 native 日历应用程序中更改某些内容并返回到我的应用程序时，选择器会被调用 4-5 次并发出不同的通知。</p>
<p>在 <code>viewDidLoad</code> 中，我删除所有可能的观察者并注册一次 agian:</p>
<pre><code>NotificationCenter.default.removeObserver(self)
NotificationCenter.default.addObserver(self, selector: #selector(reloadModelData(notification:)), name: Notification.Name.EKEventStoreChanged, object: nil)
</code></pre>
<p>对应的方法:</p>
<pre><code>@objc private func reloadModelData(notification: NSNotification) {
debugPrint("method called \(notification)")
}
</code></pre>
<p>导致这个输出</p>
<blockquote>
<p>"method called NSConcreteNotification 0x170246300 {name = EKEventStoreChangedNotification; object = ; userInfo = {\n EKEventStoreChangedObjectIDsUserInfoKey = (\n \"x-apple-eventkit:///Location/p259707\",\n \"x-apple-eventkit:///Event/p264955\"\n );\n}}"
"method called NSConcreteNotification 0x174258840 {name = EKEventStoreChangedNotification; object = ; userInfo = {\n EKEventStoreChangedObjectIDsUserInfoKey = (\n \"x-apple-eventkit:///Location/p259707\",\n \"x-apple-eventkit:///Event/p264955\"\n );\n}}"
"method called NSConcreteNotification 0x17024b250 {name = EKEventStoreChangedNotification; object = ; userInfo = {\n EKEventStoreChangedObjectIDsUserInfoKey = (\n \"x-apple-eventkit:///Location/p259707\",\n \"x-apple-eventkit:///Event/p264955\"\n );\n}}"
"method called NSConcreteNotification 0x174253b00 {name = EKEventStoreChangedNotification; object = ; userInfo = {\n EKEventStoreChangedObjectIDsUserInfoKey = (\n \"x-apple-eventkit:///Location/p259707\",\n \"x-apple-eventkit:///Event/p264955\"\n );\n}}"</p>
</blockquote>
<p>有谁知道如何解决这个问题。意思是在重新进入应用时只收到该观察者的一次调用？</p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>我猜，这就是它的工作原理，日历会向您发送有关您所做的所有原始更改的通知。</p>
<p> <a href="https://developer.apple.com/reference/foundation/nsnotification.name/1507525-ekeventstorechanged" rel="noreferrer noopener nofollow">The Apple's documentation</a>建议通过调用 <code>refresh</code> 检查您正在访问的提醒和事件。如果它返回 <code>true</code>，则无需重新获取它们。所以多个通知到达不会造成太大问题。</p>
<p>我还建议在 <code>viewWillAppear(_:)</code> 中订阅通知并在 <code>viewDidDisappear(_:)</code> 中取消订阅。当然可能会有异常(exception)，但通常你不想在屏幕不活动时处理它们。</p></p>
<p style="font-size: 20px;">关于ios - 带有 EKEventStoreChanged 通知的 NotificationCenter 使用不同的通知多次调用，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/40613478/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/40613478/
</a>
</p>
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