Using Instruments to trace memory leak Xcode5 and iOS7
automatic-ref-counting, calayer, camera, ios, memory-leaks
Solution
Here's my theory: what you've encountered is evidently a bug (or flaw) in Apple's own code, and all you can do is laugh maniacally and forget about it.
To test my theory, I ran my own code, written totally separately and at a different time. It does almost the same thing your code does: it lets the user take a picture, and puts the image into the interface. Here's my code:
https://github.com/mattneub/Programming-iOS-Book-Examples/blob/master/bk2ch17p702takeAPicture/ch30p962takeAPicture/ViewController.m
I ran my code under Instruments with the Leaks instrument, and guess what? I saw the same issues you did.
Naturally, I then started searching on Stack Overflow, and all of this turns out to be old ground. For example:
UIImagePickerController memory leak on iOS5
Even Apple's own sample code, called PhotoPicker (or Using UIImagePickerController to Select Pictures and Take Photos) has the same leak.
Problem
I developed my first app and still learning. Just updated Xcode 5 yesterday and my iPhone 5 is running iOS 7.1. I am now working on understanding the Instruments tool to analyze my app. I am using the Leak profile in Instruments and have come across a retain cycle and leak which I can't figure out. Appreciate any help I can get to understand a) how to pinpoint the bug and b) what I did wrong and how to avoid it in the future. In my app, I am using the camera to take a pic. While the camera is up, I tapped on the screen to focus and that is when I noticed the leak pop up in Instruments. Looks like there is a retain cycle not in my code (if I understand correctly) and a root leak in my code which I don't understand. I am using ARC, so I should not have to release "picker" in the part of my code that Instruments is pointing me to (part 2 below, with code). - What can I do about the retain cycle. It is not in my code, but am I still the cause of it? Does it stem from the "root leak?" If I am NOT responsible for it, what's should I do about it? - My only code in this stack trace does not help me understand where the leak is coming from. The line is Instruments points me to in my code is [picker dismissViewControllerAnimated:YES completion:nil]; in my imagePickerController:didFinishPickingMediaWithInfo: method. I am pasting the code below. ``` - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info { UIImage *pickerImage = [info objectForKey: UIImagePickerControllerOriginalImage]; _imageView.image = pickerImage; [picker dismissViewControllerAnimated:YES completion:nil]; // <--- mem-leak } ``` EDIT - Code where I create my UIImagePickerController. ``` - (IBAction)snapPicture:(id)sender { UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init]; // If the camera button was tapped AND we have a camera, use it... if ((sender == _cameraButton) && [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) { [imagePicker setSourceType:UIImagePickerControllerSourceTypeCamera]; } else { [imagePicker setSourceType:UIImagePickerControllerSourceTypePhotoLibrary]; } imagePicker.delegate = self; // bring up the image picker view [self presentViewController:imagePicker animated:YES completion:nil]; } ```