Question: ![enter image description here](https://i.stack.imgur.com/QRTZ2.png)I am developing an app that captures images from iDevice's camera and upload it to web service. 

**NO problem everything is working fine except the device's camera. Device's camera is driving my crazy. I am using below code to allow user to capture images. Sometimes camera shows preview and sometimes doesn't. Instead of preview is just shows complete darkness on screen. If I switch from rear to front camera is starts working fine. I have even trying deleting all background apps from device and clearing as much memory as I could; still no luck and I am stuck. :(**

```
- (IBAction)addNewImage:(id)sender
{
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.delegate = self;

    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
    {
        // Take picture from camera
        imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;

        // set no to take as much pictures as user want.
        imagePicker.showsCameraControls = YES;

        // Show user the camera
        [self presentModalViewController:imagePicker
                                animated:YES];
    }
    else
    {
        imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        [self presentModalViewController:imagePicker
                                animated:YES];        
    }    
}

```

Answer: 
I had faced this issue in my app. Though I never found out the what the issue was, I rewrote my code to define a property of `UIIMagePickerController` type and initialize it once in the getter. Used this property to initialize the camera view :

getter:

```
-(UIImagePickerController *) imagePicker{
    if(!_imagePicker){
       _imagePicker = [[UIImagePickerController alloc] init];
       _imagePicker.delegate = self;
       if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
           _imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
       }
       else{
           _imagePicker.sourceType =UIImagePickerControllerSourceTypePhotoLibrary;
       }  

   }
    return _imagePicker;
}

- (IBAction)addNewImage:(id)sender{
  if (self.imagePicker)
  {
      [self presentViewController:self.imagePicker animated:YES completion:^{}];
  }
}

```

For some reason this got rid of the issue with preview sometimes showing a black screen
In ios7, you should set mainWindow.rootViewController = a class has kind is UIViewController. It's work for me.
If rootViewController is other, ex: UITabbarController, UINavigationController..., the black screen of camera will appear.