Question

I’m suddenly getting this warning after upgrading

Incorrect decrement of the reference count of an object that is not owned at this point by the caller

Any ideas ?

+ (void) drawGradientInRect:(CGRect)rect withColors:(NSArray*)colors{

    NSMutableArray *ar = [NSMutableArray array];
    for(UIColor *c in colors){
        [ar addObject:(id)c.CGColor];
    }


    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSaveGState(context);



    CGColorSpaceRef colorSpace = CGColorGetColorSpace([[colors lastObject] CGColor]);
    CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (CFArrayRef)ar, NULL);


    CGContextClipToRect(context, rect);

    CGPoint start = CGPointMake(0.0, 0.0);
    CGPoint end = CGPointMake(0.0, rect.size.height);

    CGContextDrawLinearGradient(context, gradient, start, end, kCGGradientDrawsBeforeStartLocation | kCGGradientDrawsAfterEndLocation);

    CGColorSpaceRelease(colorSpace);  //on this line
    CGGradientRelease(gradient);
    CGContextRestoreGState(context);

}

Answer 1

Yep. You are getting a CGColorSpaceRef through the CGColorGetColorSpace function.

According to the ‘Create/Copy’ rule, you don’t have the ownership on that object.

So you don’t need to release it, with CGColorSpaceRelease.

Only release an object you explicitly allocated or copied.

This is valid for Objective-C, as well as for CF style classes.

In Objective-C, it means that a call to alloc or a call to copy (and of course an explicit call to retain) will need a release.

With CF classes, you need to release if you acquired an object with a method with ‘create’ or ‘copy’ in its name. Of course, an explicit call to CFRetain will also need a release.

For your information, it’s even said in the documentation of the CGColorGetColorSpace function, even if the ‘Create/Copy’ rule is just clear about this:

You are responsible for retaining and releasing it as needed.

Meaning the object won’t persist in memory if you don’t retain it explicitly. So if you don’t, you don’t need to release it.