How do I know if cellular access for my iOS app is disabled?

问题

I have an iOS app that makes some small network requests on app launch (resource updates, etc). If the user turns off cellular access for the app in iOS Settings, they get a prompt from iOS about network usage every time they launch. Is there a way to know programmatically that cellular data for this app has been disabled, so that I can disable the requests at startup?

回答1:

So I found this on the apple dev forums from an Apple engineer (https://devforums.apple.com/message/1059332#1059332).

Another developer wrote in to DTS and thus I had a chance to investigate this in depth. Alas, the news is much as I expected: there is no supported way to detect that your app is in this state. Nor is there a way to make a "no user interaction" network connection, that is, request that the connection fail rather than present UI like this. If these limitations are causing problems for your app, I encourage you to file a bug describing your specific requirements.
https://developer.apple.com/bug-reporting/

So it looks like it is not possible to detect if cellular data for your app has been turned off.

Edit

I filed a radar for this requesting that it be added. I just got this notification in my radar

We believe this issue has been addressed in the latest iOS 9 beta.

I looked through the API diffs, but so far I can't find the new API.

回答2:

As of iOS9, the capability to check the setting to enable/disable use of cellular data for your app (Settings/Cellular/AppName) is available using Apple's CTCellularData class. The following code will set cellularDataRestrictedState when it is run initially and then set it and log whenever it changes:

import CoreTelephony
var cellularDataRestrictedState = CTCellularDataRestrictedState.restrictedStateUnknown
let cellState = CTCellularData.init()
cellState.cellularDataRestrictionDidUpdateNotifier = { (dataRestrictedState) in
  if cellularDataRestrictedState != .restrictedStateUnknown { // State has changed - log to console
    print("cellularDataRestrictedState: " + "\(dataRestrictedState == .restrictedStateUnknown ? "unknown" : dataRestrictedState == .restricted ? "restricted" : "not restricted")")
  }
  cellularDataRestrictedState = dataRestrictedState
}

Unfortunately (as of iOS11) this seems to check only the state of the app's switch - if your app's switch is set to enabled and the user switches the Cellular Data master switch to disabled, this API will return the app's state as being "not restricted".

回答3:

Just wanted to add an Objective C version of the above Swift code for future travellers.

- (void)monitorCanUseCellularData {
    if (GCIsiOS9) {
        CTCellularData *cellularData = [[CTCellularData alloc] init];
        NSLog(@"%ld", cellularData.restrictedState);
        // 0, kCTCellularDataRestrictedStateUnknown
        [cellularData setCellularDataRestrictionDidUpdateNotifier:^(CTCellularDataRestrictedState state) {
            NSLog(@"%ld", state);
            self.canUseCellularData = cellularData.restrictedState ==2?true:false;
        }];
    }
}

回答4:

I have found that the CTCellularData class needs some time to get to the correct value. In my implementation I call the didUpdateNotifier very early after appDidFinishLaunching. By the time my networking call are returning with errors I definitely have a correct value for the restricted state.

class CellularRestriction: NSObject {
    private static var cellularData = CTCellularData()
    private static var currentState = CTCellularDataRestrictedState.restrictedStateUnknown

    static var isRestricted: Bool {
        currentState = cellularData.restrictedState
        return currentState == .restricted
    }

    static func prepare() {
        if currentState == .restrictedStateUnknown {
            cellularData.cellularDataRestrictionDidUpdateNotifier = { state in
                currentState = cellularData.restrictedState // This value may be inconsistent, however the next read of isRestricted should be correct.
            }
        }
    }
}

回答5:

Adding to dirkgroten's answer, you can use the Apple Reachability class, found here:

https://developer.apple.com/Library/ios/samplecode/Reachability/Introduction/Intro.html

It uses SCNetworkReachability, and is very straight forward to use, it will detect connectivity via Cell and WiFi as you will need to check both at start up.

回答6:

There are lots of frameworks out there that will give you the status of your network connectivity, and of course you can roll your own. I've found AFNetworking to be one of the best. It has a singleton class called AFNetworkReachabilityManager that abstracts some of the complexities for you. Specifically you'll want to look at the two boolean properties:

reachableViaWWAN
reachableViaWiFi

There is also a reachability changed status block that you can set:

– setReachabilityStatusChangeBlock:

AFNetworking Github

AFNetworkReachabilityManager

来源：https://stackoverflow.com/questions/22563526/how-do-i-know-if-cellular-access-for-my-ios-app-is-disabled

标签

ios

networking

cellular-network