如何检测是否在iOS 14中授予了本地网络权限 [英] How to detect if Local Network permissions are granted in iOS 14

问题描述

如何检测用户是否在iOS 14的应用程序中授予了本地网络权限?如果用户拒绝了权限并重定向到os设置以授予权限，则必须显示错误屏幕. Apple是否提供了任何类似位置许可的查找方法?

How to detect if the user has granted the local network permission in the app for iOS 14? I have to show an error screen if the user has denied permission and redirects to os settings to grant permission. Has Apple provided any way to find out just like location permission?

推荐答案

我编写了此类，如果您不在iOS 14.2上，可以使用该类.

I wrote up this class that can be used if you're not on iOS 14.2.

• 此类将提示用户(首次)访问本地网络的权限.
• 如果已被拒绝/授予，请验证现有的权限状态.

请记住，该实例必须保持活动状态，因此，如果您在另一个类中的函数调用中使用此实例，则需要使该实例保持活动状态，而不位于调用函数的范围之内.

Just remember this instance has to be kept alive so if you are using this in a function call within another class you need to keep the instance alive outside of the scope of the calling function.

import UIKit
import Network

class LocalNetworkPermissionChecker {
    private var host: String
    private var port: UInt16
    private var checkPermissionStatus: DispatchWorkItem?
    
    private lazy var detectDeclineTimer: Timer? = Timer.scheduledTimer(
        withTimeInterval: .zero,
        repeats: false,
        block: { [weak self] _ in
            guard let checkPermissionStatus = self?.checkPermissionStatus else { return }
            DispatchQueue.main.asyncAfter(deadline: .now(), execute: checkPermissionStatus)
        })
    
    init(host: String, port: UInt16, granted: @escaping () -> Void, failure: @escaping (Error?) -> Void) {
        self.host = host
        self.port = port
        
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(applicationIsInBackground),
            name: UIApplication.willResignActiveNotification,
            object: nil)
        
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(applicationIsInForeground),
            name: UIApplication.didBecomeActiveNotification,
            object: nil)
        
        actionRequestNetworkPermissions(granted: granted, failure: failure)
    }
    
    deinit {
        NotificationCenter.default.removeObserver(self)
    }
    
    /// Creating a network connection prompts the user for permission to access the local network. We do not have the need to actually send anything over the connection.
    /// - Note: The user will only be prompted once for permission to access the local network. The first time they do this the app will be placed in the background while
    /// the user is being prompted. We check for this to occur. If it does we invalidate our timer and allow the user to make a selection. When the app returns to the foreground
    /// verify what they selected. If this is not the first time they are on this screen, the timer will not be invalidated and we will check the dispatchWorkItem block to see what
    /// their selection was previously.
    /// - Parameters:
    ///   - granted: Informs application that user has provided us with local network permission.
    ///   - failure: Something went awry.
    private func actionRequestNetworkPermissions(granted: @escaping () -> Void, failure: @escaping (Error?) -> Void) {
        guard let port = NWEndpoint.Port(rawValue: port) else { return }
        
        let connection = NWConnection(host: NWEndpoint.Host(host), port: port, using: .udp)
        connection.start(queue: .main)
        
        checkPermissionStatus = DispatchWorkItem(block: { [weak self] in
            if connection.state == .ready {
                self?.detectDeclineTimer?.invalidate()
                granted()
            } else {
                failure(nil)
            }
        })
        
        detectDeclineTimer?.fireDate = Date() + 1
    }
    
    /// Permission prompt will throw the application in to the background and invalidate the timer.
    @objc private func applicationIsInBackground() {
        detectDeclineTimer?.invalidate()
    }
    
    /// - Important: DispatchWorkItem must be called after 1sec otherwise we are calling before the user state is updated.
    @objc private func applicationIsInForeground() {
        guard let checkPermissionStatus = checkPermissionStatus else { return }
        DispatchQueue.main.asyncAfter(deadline: .now() + 1, execute: checkPermissionStatus)
    }
}

//Can be used like this:
LocalNetworkPermissionChecker(host: "255.255.255.255", port: 4567, granted: {
    //Perform some action here...
},
failure: { error in
    if let error = error {
        print("Failed with error: \(error.localizedDescription)")
    }
})

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