在collectionViewController上以模态方式呈现imagePickerController

Question

我正试图在ImagePicker上提出collectionViewController，但每次我的代码运行时，我都会收到错误消息：

  

警告：尝试在＆lt; CameraViewController上显示UIImagePickerController：0x15c50a370：0x15c6098a0＆gt;已经呈现（null）

这是我的代码：

#import "HomeViewController.h"
#import <Parse/Parse.h>
#import "PhotoCell.h"

@interface HomeViewController ()

@end

@

implementation HomeViewController

- 

    (void)viewDidLoad
    {

    [super viewDidLoad];

    UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
    HomeViewController *vc = (HomeViewController *) [storyBoard instantiateViewControllerWithIdentifier:@"Home"];

    [vc initWithCoder:nil];

    self.edgesForExtendedLayout = UIRectEdgeNone;

    self.title = @"fade";

    self.collectionView.backgroundColor = [UIColor whiteColor];

    [self.collectionView registerClass:[PhotoCell class] forCellWithReuseIdentifier:@"photo"];

    PFUser *currentUser = [PFUser currentUser];
    if (currentUser) {
        NSLog(@"Current User: %@", currentUser.username);
    }
    else {
        [self performSegueWithIdentifier:@"showLogin" sender:self];
    }



}

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

    if ([segue.identifier isEqualToString:@"showLogin"]) {

        [segue.destinationViewController setHidesBottomBarWhenPushed:YES];
    }
}

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return 10;
}

- (UICollectionViewCell *) collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"photo";

    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];


    cell.backgroundColor = [UIColor lightGrayColor];

    return cell;
}

- (id)initWithCoder:(NSCoder*)coder
{
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];



    layout.itemSize = CGSizeMake(306.0, 306.0);
    layout.minimumInteritemSpacing = 150.0;
    layout.minimumLineSpacing = 50.0;


    return (self = [super initWithCollectionViewLayout:layout]);
}

@end