Ask permission to access Camera Roll

Question

I have a settings view where the user can choose switch on or off the feature \'Export to Camera Roll\'

When the user switches it on for the first time (and

Answer 1

Since iOS 10 we also need to provide photo library usage description in info.plist file which I described there. And then just use this code to make alert appear everytime we need:

- (void)requestAuthorizationWithRedirectionToSettings {
    dispatch_async(dispatch_get_main_queue(), ^{
        PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];
        if (status == PHAuthorizationStatusAuthorized)
        {
            //We have permission. Do whatever is needed
        }
        else
        {
            //No permission. Trying to normally request it
            [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
                if (status != PHAuthorizationStatusAuthorized)
                {
                    //User don't give us permission. Showing alert with redirection to settings
                    //Getting description string from info.plist file
                    NSString *accessDescription = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"NSPhotoLibraryUsageDescription"];
                    UIAlertController * alertController = [UIAlertController alertControllerWithTitle:accessDescription message:@"To give permissions tap on 'Change Settings' button" preferredStyle:UIAlertControllerStyleAlert];

                    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:nil];
                    [alertController addAction:cancelAction];

                    UIAlertAction *settingsAction = [UIAlertAction actionWithTitle:@"Change Settings" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
                        [[UIApplication sharedApplication] openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString]];
                    }];
                    [alertController addAction:settingsAction];

                    [[UIApplication sharedApplication].keyWindow.rootViewController presentViewController:alertController animated:YES completion:nil];
                }
            }];
        }
    });
}

Also there are some common cases when alert doesn't appear. To avoid copying I would like you to take a look at this answer.