Memory Management Issue in IOS (Received memory warning.) - iphone

Question

I have a blank screen on which i click camera button and take photo and than that photo appears on my blank screen as a UIVIew and i'm adding multiple images from Camera to blank screen. The problem is sometimes i can add multiple images on blank screen but sometimes when i capture image and than all images on blank screen disappear and just shows the current image.
And in LOG. it show me Received memory warning.
this is my code. i think i m now releasing my objects properly. but when i am adding [object release] in the end my app crashes.
-(void)AddImagesToCanvasWithGesture{
if(imageFromPicker.size.width > imageFromPicker.size.height || imageFromPicker.size.width == imageFromPicker.size.height)
{
holderView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 180, 160)];
}
else{
holderView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 160, 240)];
}
UIImageView *imageview = [[[UIImageView alloc] initWithFrame:[holderView frame]];
[imageview setImage:imageFromPicker];
//[imageview setTag:101];
//[holderView setTag:102];
//NSLog(#"Tag By Default %d",(arc4random()%100)+10);
[holderView setTag:(int)objectDelegate.tagForHolderView];
[imageview setTag:((int)objectDelegate.tagForHolderView)+1];
[holderView addSubview:imageview];
//[imageview canBecomeFirstResponder];
UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:#selector(scale:)];
[pinchRecognizer setDelegate:self];
[holderView addGestureRecognizer:pinchRecognizer];
UIRotationGestureRecognizer *rotationRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:#selector(rotate:)];
[rotationRecognizer setDelegate:self];
[holderView addGestureRecognizer:rotationRecognizer];
UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(move:)];
[panRecognizer setMinimumNumberOfTouches:1];
[panRecognizer setMaximumNumberOfTouches:1];
[panRecognizer setDelegate:self];
[holderView addGestureRecognizer:panRecognizer];
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapped:)];
[tapRecognizer setNumberOfTapsRequired:1];
[tapRecognizer setDelegate:self];
[holderView addGestureRecognizer:tapRecognizer];
UILongPressGestureRecognizer *gestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(gestureHandler:)];
[holderView addGestureRecognizer:gestureRecognizer];
[holderView.layer setBorderColor: [[UIColor whiteColor] CGColor]];
[holderView.layer setBorderWidth: 3.0];
[self.view addSubview:holderView];
objectDelegate.tagForHolderView+=2;
for(UIButton *b in self.view.subviews) {
if([b isKindOfClass:[UIButton class]]) {
[self.view bringSubviewToFront:b];
}
[self.view sendSubviewToBack:imageViewForBackground];
//[holderView setHidden:YES];
}
}
how can i release them and where should i call the release method.

Answer 1

From the code snippet you have added above, it's obvious the you are not releasing objects properly. You own every object that you init or retain or copy and you are responsible to release them unless you are using ARC. (The code above is fine for ARC).
You have ownership of all the gesture recognizers and image view and you should release them as soon as you no longer need them. For instance... imageView object must be released after
[holderView addSubview:imageview];
and
pinchRecognizer should be released right after
[holderView addGestureRecognizer:pinchRecognizer];
Same goes for other gesture recognizers.
I guess you have similar kind of problems in other parts of your code too and eventually the app receives memory warning.

Answer 2

When you have a memory problem, if you have a method named
- (void)didReceiveMemoryWarning
it will get called and allow you to free up space. If you are using ARC, just set your UIImageView to nil, if not, call:
[imageview release];