MPMediaPicker does not show

Question

In a sample app that I'm making for Apple, I cannot get the MPMediaPickerController to show.

I've already added the NSAppleMusicUsageDescription key in the info.plist file, and this is what makes my post different from any other answers found online.

I've also tried adding CoreMedia.framework.

I'm using XCode 10 beta 4

The app never asks for permissions to access the media library, and when I present the picker, the mediaPickerDidCancel method is called right away.

What am I doing wrong?

Thanks for any help!

Header file:

#import <UIKit/UIKit.h>
#import <MediaPlayer/MPMediaPickerController.h>

@interface ViewController : UIViewController<MPMediaPickerControllerDelegate>

@end

Objc file:

#import "ViewController.h"
#import <MediaPlayer/MediaPlayer.h>

@interface ViewController ()

@end

@implementation ViewController {
    MPMediaPickerController *picker;
}

- (void)viewDidLoad {
    [super viewDidLoad];
}

- (IBAction)selectButtonPressed:(id)sender {

    picker = [[MPMediaPickerController alloc] initWithMediaTypes: MPMediaTypeAnyAudio];
    [picker setDelegate: self];
    [picker setAllowsPickingMultipleItems: NO];
    picker.prompt = @"Select a Song.";

    UIViewController *rootController = [UIApplication sharedApplication].keyWindow.rootViewController;

    [rootController presentViewController:picker animated:YES completion:^{
        NSLog(@"Complete!");
    }];
}

- (void) mediaPicker: (MPMediaPickerController *) mediaPicker didPickMediaItems: (MPMediaItemCollection *) collection {

    MPMediaItem *firstItem;
    for (MPMediaItem *item in collection.items) {
        firstItem = item;
        break;
    }

    MPMusicPlayerController *samplePlayer  = [MPMusicPlayerController applicationMusicPlayer];
    [samplePlayer setShuffleMode: MPMusicShuffleModeOff];
    [samplePlayer setRepeatMode: MPMusicRepeatModeOne];
    [samplePlayer beginGeneratingPlaybackNotifications];

    // self.mediaItem chosen using MPMediaPickerController
    [samplePlayer setQueueWithItemCollection:[[MPMediaItemCollection alloc] initWithItems:@[firstItem]]];
    [samplePlayer prepareToPlay];

    // Assume that song is at least 120 seconds long
    [samplePlayer play];
}

#pragma mark - delegate methods and segues

- (void) mediaPickerDidCancel: (MPMediaPickerController *) mediaPicker {
    [self dismissViewControllerAnimated:true completion:^{
    }];
}
@end