Question

So i’m working on an application, and i’m not using automatic reference counting, so i have to do my own memory management. I have this code, which sets a value to a UIView’s layer in a first method.
Then in a second method, i retrieve it. array1 is defined in my viewDidLoad

Here is my first Method

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
    UITouch *touch = [touches anyObject];
   CGFloat endLocation = [touch locationInView:self];
    CGRect rect = CGRectMake(startLocation.x, startLocation.y, endLocation.x, endLocation.y);
    UIView *rectstring = [[UIView alloc]initWithFrame:rect];
    NSString *string = [NSString stringWithFormat:@"%d",pencilbool];
    [[rectstring layer] setValue:string forKey:@"color"];
    NSString *string1 = [NSString stringWithFormat:@"%f",stepper.value];
    [[rectstring layer] setValue:string1 forKey:@"size234"];

        [array1 addObject:rectstring];
        [rectstring release];
        [string release];
        [string1 release];

}

Second method:

 -(IBAction)secondmethod {
        for (UIView *string1 in array1) {
            CGContextRef gc=UIGraphicGetCurrentContext();
            CGFloat width =[[string1.layer valueForKey:@"size234"] floatValue];
            CGContextSetLineWidth (gc, width);
            CGRect rect = [string1 frame];
            CGContextMoveToPoint(gc, rect.origin.x, rect.origin.y);
            CGContextAddLineToPoint(gc, rect.size.width, rect.size.height);
            CGContextStrokePath(gc);
        }
    }

this causes an error at CGFloat width =[[string1.layer valueForKey:@"size234"] floatValue];.
However, if i remove the release calls in the first method:

 [string release];
 [string1 release];

It runs fine.

Why is this causing an error? Any ideas?

Answer 1

The non-ARC rule is to only release things that you’ve retained, explicitly or by calling such things as alloc or copy. (More exact documentation is at: https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/MemoryMgmt/Articles/mmRules.html ) stringWithFormat: returns an autoreleased object, which means you shouldn’t be adding another release.