Question

我在Swift代码中有一个函数scheduleFutureLocalNotifications()，它会创建64 UILocalNotification，以便将来触发。

最初该函数是在viewDidLoad()调用的，但是在启动应用程序时会导致延迟。

接下来，在活动应用程序期间调用了该函数，但这会导致不可预测的暂停或滞后用户界面。

最后，当应用程序在收到UIApplicationDidEnterBackground通知后转换到后台时，该功能被移动以触发，但这会导致iOS在后台准备本地通知时暂时滞后。这在旧设备上显得更为明显。

问题：

1 - 如何减少延迟并提高用户界面响应能力   创建本地通知？

2 - 可以采用哪些更好的技术来安排64   通知？

3 - 有什么其他更好的时间可以调用函数scheduleFutureLocalNotifications()？

代码：

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        scheduleFutureLocalNotifications()
    }

    func scheduleFutureLocalNotifications() {

        // Remove all previous local notifications
        let application = UIApplication.sharedApplication()
        application.cancelAllLocalNotifications()

        // Set new local notifications to fire over the coming 64 days
        for nextLocalNotification in 1...64 {

            // Add calendar day
            let addDayComponent = NSDateComponents()
            addDayComponent.day = nextLocalNotification
            let calendar = NSCalendar.currentCalendar()
            let nextDate = calendar.dateByAddingComponents(addDayComponent, toDate: NSDate(), options: [])

            // Set day components for next fire date
            let nextLocalNotificationDate = NSCalendar.currentCalendar()
            let components = nextLocalNotificationDate.components([.Year, .Month, .Day], fromDate: nextDate!)
            let year = components.year
            let month = components.month
            let day = components.day

            // Set notification fire date
            let componentsFireDate = NSDateComponents()
            componentsFireDate.year = year
            componentsFireDate.month = month
            componentsFireDate.day = day
            componentsFireDate.hour = 0
            componentsFireDate.minute = 0
            componentsFireDate.second = 5
            let fireDateLocalNotification = calendar.dateFromComponents(componentsFireDate)!

            // Schedule local notification
            let localNotification = UILocalNotification()
            localNotification.fireDate = fireDateLocalNotification
            localNotification.alertBody = ""
            localNotification.alertAction = ""
            localNotification.timeZone = NSTimeZone.defaultTimeZone()
            localNotification.repeatInterval = NSCalendarUnit(rawValue: 0)
            localNotification.applicationIconBadgeNumber = nextLocalNotification

            application.scheduleLocalNotification(localNotification)
        }
    }
}

Answer 1

您可以异步地将该函数调度到另一个队列。这将确保主队列不会被阻止执行调度，并将阻止UI无响应：

override func viewDidLoad() {
    super.viewDidLoad()

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIO‌RITY_BACKGROUND, 0)) {
        scheduleFutureLocalNotifications()
    } 
}

调度UILocalNotification导致用户界面滞后和延迟

1 个答案: