Camera app displaying white screen - iphone

Question

Im newish to Objective-C and I want to create an app with that will eventually take pictures with the camera but with images overlaid. But I thought I would start with a simple camera app just to get the base for it. I have followed a tutorial for creating a app that you can take pictures with and access image library. BUT when I build it to my iPhone 4s it just loads a white screen. If any one could take a look at the code, but I think its right and offer an answer it would be great thanks.
//ViewController.h
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController
<UIImagePickerControllerDelegate, UINavigationControllerDelegate>
#property (strong, nonatomic) IBOutlet UIImageView *imageView;
- (IBAction)takePhoto:(UIButton *)sender;
- (IBAction)selectPhoto:(UIButton *)sender;
#end
//ViewController.m
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
UIAlertView *myAlertView = [[UIAlertView alloc] initWithTitle:#"Error"
message:#"Device has no camera"
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles: nil];
[myAlertView show];
}
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
}
- (IBAction)takePhoto:(UIButton *)sender {
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
[self presentViewController:picker animated:YES completion:NULL];
}
- (IBAction)selectPhoto:(UIButton *)sender {
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
[self presentViewController:picker animated:YES completion:NULL];
}
#pragma mark - Image Picker Controller delegate methods
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
UIImage *chosenImage = info[UIImagePickerControllerEditedImage];
self.imageView.image = chosenImage;
[picker dismissViewControllerAnimated:YES completion:NULL];
}
- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
[picker dismissViewControllerAnimated:YES completion:NULL];
}
#end