Core Image help: Setting CIImage from UIImage via UIImagePicker (then filtering it) - xcode

Question

Searched around on SO for an answer. Found some interesting stuff but I am still stuck.
In a view controller I have a UIImageView which I set an image taken from UIImagePicker when the view loads.
(I also set a CIImage at the same time)
I have two sliders (one for brightness, one for contrast). Upon moving the slider, a filter is applied to the CIImage, then the CIImage is rendered into the the UIImageView's UIImage.
Fist off, the UIImage taken from UIImagePicker does show up correctly when first selected.
I also have my slider ranges set correctly and have verified the proper float values are being passed to the delegate functions (via NSLog).
However, when I try playing with the sliders, my UIImageView turns white! Perhaps you folks can help. I'll post some code snippets:
First, my #interface:
#interface PrepViewController : UIViewController <UIImagePickerControllerDelegate , UINavigationControllerDelegate>
#property (weak, nonatomic) IBOutlet UIImageView *editingImage;
#property (weak, nonatomic) CIImage *editingCIImage;
#property (weak, nonatomic) CIContext *editingCIContext;
#property (weak, nonatomic) CIFilter *editingCIFilter;
#property (nonatomic) BOOL didAskForImage;
#property (weak, nonatomic) IBOutlet UISlider *brightnessSlider;
#property (weak, nonatomic) IBOutlet UISlider *contrastSlider;
- (void) doImageFilter:(NSString *)filter withValue:(float)value;
#end
My viewDidLoad, pretty simple just sets didAskForImage to NO
- (void)viewDidLoad
{
[super viewDidLoad];
self.didAskForImage = NO;
}
viewDidAppear is where I check if I've already asked for the image, then ask for it
- (void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
if(!self.didAskForImage){
UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = NO;
UIImagePickerControllerSourceType sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
sourceType = UIImagePickerControllerSourceTypeCamera;
}
picker.sourceType = sourceType;
[self presentModalViewController:picker animated:YES];
}
}
Here is the imagePickerController didFinishPickingImage delegate method
this is where I actually set the UIImageView's image property and initialize the CIImage, CIContext, and CIFilter objects.
I also set the didAskForImage boolean and the slider targets.
-(void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingImage : (UIImage *)image
editingInfo:(NSDictionary *)editingInfo
{
self.didAskForImage = YES;
self.editingImage.image = image;
self.editingCIImage = [[CIImage alloc] initWithImage:image];
self.editingCIContext = [CIContext contextWithOptions:nil];
self.editingCIContext = [CIContext contextWithOptions:nil];
self.editingCIFilter = [CIFilter filterWithName:#"CIColorControls" keysAndValues:kCIInputImageKey, self.editingCIImage, nil];
[self.contrastSlider addTarget:self action:#selector(contrastMove:) forControlEvents:UIControlEventValueChanged];
[self.brightnessSlider addTarget:self action:#selector(brightnessMove:) forControlEvents:UIControlEventValueChanged];
[picker dismissModalViewControllerAnimated:YES];
}
and the cancel delegate
-(void)imagePickerControllerDidCancel:(UIImagePickerController *) picker
{
[picker dismissModalViewControllerAnimated:YES];
picker = nil;
[self.navigationController popToViewController:[self.navigationController.viewControllers objectAtIndex:0] animated:YES];
}
Here are the sliders' delegate methods. Again, the NSLogs display the expected values.
- (void) contrastMove:(id)sender{
NSLog(#"%f", [(UISlider *)sender value]);
[self doImageFilter:#"inputContrast" withValue:[(UISlider *)sender value]];
}
- (void) brightnessMove:(id)sender{
NSLog(#"%f", [(UISlider *)sender value]);
[self doImageFilter:#"inputBrightness" withValue:[(UISlider *)sender value]];
}
And finally, here is the doImageFilter method I created, which actually does the filter and reassigns the UIImageView (this is where it turns white)
- (void) doImageFilter:(NSString *)filter withValue:(float)value{
[self.editingCIFilter setValue:[NSNumber numberWithFloat:value] forKey:filter];
CIImage *output = [self.editingCIFilter outputImage];
CGImageRef cgi = [self.editingCIContext createCGImage:output fromRect:[output extent]];
self.editingCIImage = output;
self.editingImage.image = [UIImage imageWithCGImage:cgi];
}
So I have a hunch that the CIImage isn't even being initialized properly in the first place; but I don't know why. Been at this for a couple hours now.
Thanks for all your help!
Cheers

Answer 1

Hahaha, oh wow.
So I figured it out, my CIContext and CIFilter need to be set to strong instead of weak.
Awesome.