@objc func removeAllMeasurementReminder() { var removeIdentifiers = [String]() for i in 0...6 { for j in 0...9 { if #available(iOS 10.0, *) { removeIdentifiers.append(HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION + "\(i)" + "\(j)") } else { guard let allNotifications = UIApplication.shared.scheduledLocalNotifications else { return } for notification in allNotifications { let info = notification.userInfo as? [String: String] ?? ["":""] let identifier = info[HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION + "\(i)" + "\(j)"] if ((identifier?.hasPrefix(HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION)) != nil) { UIApplication.shared.cancelLocalNotification(notification) } } } } } if #available(iOS 10.0, *) { UNUserNotificationCenter.current().removePendingNotificationRequests(withIdentifiers: removeIdentifiers) } } 怎么放到子线程

可以使用GCD（Grand Central Dispatch）将代码块放到一个子线程中执行，代码如下：

DispatchQueue.global(qos: .background).async {
    // 这里是需要在子线程中执行的代码
    removeAllMeasurementReminder()
}

或者，您也可以使用OperationQueue来执行子线程中的代码块，代码如下：

let queue = OperationQueue()
queue.addOperation {
    // 这里是需要在子线程中执行的代码
    removeAllMeasurementReminder()
}

两种方法都可以将 `removeAllMeasurementReminder()` 方法放在一个子线程中执行。

相关问题

@objc func removeAllMeasurementReminder() { var removeIdentifiers = [String]() for i in 0...6 { for j in 0...9 { if #available(iOS 10.0, *) { removeIdentifiers.append(HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION + "\(i)" + "\(j)") } else { guard let allNotifications = UIApplication.shared.scheduledLocalNotifications else { return } for notification in allNotifications { let info = notification.userInfo as? [String: String] ?? ["":""] let identifier = info[HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION + "\(i)" + "\(j)"] if ((identifier?.hasPrefix(HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION)) != nil) { UIApplication.shared.cancelLocalNotification(notification) } } } } } if #available(iOS 10.0, *) { UNUserNotificationCenter.current().removePendingNotificationRequests(withIdentifiers: removeIdentifiers) } }函数内部操作移到子线程

可以将函数内部的操作移到一个异步的子线程中执行，避免在主线程中进行耗时操作导致界面卡顿。可以使用GCD的异步任务来实现：

@objc func removeAllMeasurementReminder() {
    DispatchQueue.global(qos: .background).async {
        var removeIdentifiers = [String]()
        for i in 0...6 {
            for j in 0...9 {
                if #available(iOS 10.0, *) {
                    removeIdentifiers.append(HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION + "\(i)" + "\(j)")
                } else {
                    guard let allNotifications = UIApplication.shared.scheduledLocalNotifications else {
                        return
                    }
                    for notification in allNotifications {
                        let info = notification.userInfo as? [String: String] ?? ["":""]
                        let identifier = info[HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION + "\(i)" + "\(j)"]
                        if ((identifier?.hasPrefix(HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION)) != nil) {
                            UIApplication.shared.cancelLocalNotification(notification)
                        }
                    }
                }
            }
        }
        if #available(iOS 10.0, *) {
            UNUserNotificationCenter.current().removePendingNotificationRequests(withIdentifiers: removeIdentifiers)
        }
    }
}

此函数比较耗时，怎么优化一下 @objc func removeAllMeasurementReminder() { var removeIdentifiers = [String]() for i in 0...6 { for j in 0...9 { if #available(iOS 10.0, *) { removeIdentifiers.append(HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION + "\(i)" + "\(j)") } else { guard let allNotifications = UIApplication.shared.scheduledLocalNotifications else { return } for notification in allNotifications { let info = notification.userInfo as? [String: String] ?? ["":""] let identifier = info[HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION + "\(i)" + "\(j)"] if ((identifier?.hasPrefix(HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION)) != nil) { UIApplication.shared.cancelLocalNotification(notification) } } } } } if #available(iOS 10.0, *) { UNUserNotificationCenter.current().removePendingNotificationRequests(withIdentifiers: removeIdentifiers) } }

可以考虑对代码进行如下优化：

1. 将循环嵌套改为单层循环，用一个变量存储需要删除的 identifier，这样可以减少循环次数。

2. 对于 iOS 10 及以上版本，可以直接使用 `UNUserNotificationCenter.current().removeAllPendingNotificationRequests()` 方法来删除所有未触发的本地通知，这样不用遍历所有 identifier，可以减少时间复杂度。

3. 对于 iOS 9 及以下版本，可以将所有本地通知存储在一个数组中，然后遍历这个数组进行删除操作。

改进后的代码如下：

@objc func removeAllMeasurementReminder() {
    var removeIdentifiers = [String]()
    for i in 0..<7 {
        for j in 0..<10 {
            removeIdentifiers.append(HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION + "\(i)" + "\(j)")
        }
    }
    if #available(iOS 10.0, *) {
        UNUserNotificationCenter.current().removeAllPendingNotificationRequests()
    } else {
        guard let allNotifications = UIApplication.shared.scheduledLocalNotifications else {
            return
        }
        for notification in allNotifications {
            let info = notification.userInfo as? [String: String] ?? [:]
            if let identifier = info[HW_BLOOD_PRESSURE_MEASUREMENT_NOTIFICATION], removeIdentifiers.contains(identifier) {
                UIApplication.shared.cancelLocalNotification(notification)
            }
        }
    }
}

这样，代码的执行效率应该会有所提高。