Show an alert when iOS app is in the background

Question

I want to show an alert view when my iOS app is in the background (and it\'s using location).

For example, the Uber Partner (Driver) app

Answer 1

After some static analysis of the binary, it became clear that they are not using PKPushRegistry (VOIP), undocumented NSNotificationCenter calls or SBAlertItem.

Took a little while to find it, but they are actually using CFUserNotification for the alerts. The class is documented for Mac, but private for iOS.

I found the usage by doing this:

nm -u ~/Downloads/Payload/UberDriver.app/UberDriver | grep CFUserNotification

The output is:

_CFUserNotificationCancel
_CFUserNotificationCreate
_CFUserNotificationCreateRunLoopSource
_kCFUserNotificationAlertHeaderKey
_kCFUserNotificationAlertMessageKey
_kCFUserNotificationAlertTopMostKey
_kCFUserNotificationAlternateButtonTitleKey
_kCFUserNotificationDefaultButtonTitleKey
_kCFUserNotificationSoundURLKey

If I grep for PKPushRegistry or for SBAlertItem, both return no results.

Can use the class by importing this file to your project.

UPDATE

I have 'working' code, however it immediately calls the callback function (responseFlags set to kCFUserNotificationCancelResponse) without showing the alert..

I am using the same keys and calls as the Uber app (compare code below to list above), so there must be something extra. Will keep looking.

#import "CFUserNotification.h"

@interface AppDelegate ()
@property (nonatomic) CFRunLoopSourceRef runLoopSource;
@property (nonatomic) CFUserNotificationRef notification;
@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    SInt32 error;
    NSDictionary *keys = @{(__bridge NSString*)kCFUserNotificationAlertHeaderKey: @"Hello",
                           (__bridge NSString*)kCFUserNotificationAlertMessageKey: @"World",
                           (__bridge NSString*)kCFUserNotificationAlertTopMostKey: @YES,
                           (__bridge NSString*)kCFUserNotificationDefaultButtonTitleKey: @"asdf",
                           (__bridge NSString*)kCFUserNotificationAlternateButtonTitleKey: @"asdf",
                           };

    self.notification = CFUserNotificationCreate(NULL, 10, kCFUserNotificationPlainAlertLevel, &error, (__bridge CFDictionaryRef)keys);
    self.runLoopSource = CFUserNotificationCreateRunLoopSource(NULL, self.notification, NotificationCallback, 0);
    CFRunLoopAddSource(CFRunLoopGetMain(), self.runLoopSource, kCFRunLoopCommonModes);

    return YES;
}

void NotificationCallback(CFUserNotificationRef userNotification, CFOptionFlags responseFlags) {
    NSLog(@"got response: %lu", responseFlags);
}