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xcodecocoacore-foundationanalyzer

Xcode analyzer complaining of CFContextRef stored in an "assign" @property

I have a Cocoa class that needs to keep a bitmap context around for a long time to do pixel manipulation.

@property (assign, nonatomic) CGContextRef cacheContext; // block of pixels

in my class init:

// this creates a 32bit ARGB context, fills it with the contents of a UIImage and returns a CGContextRef
[self setCacheContext:[self allocContextWithImage:[self someImage]]];

and in dealloc:

CGContextRelease([self cacheContext]);

The Xcode analyzer companies about the init leaking an object of type CGContextRef and in the dealloc there is a complaint about "incorrect decrement of an object that is not owned by the caller".

I believe this is all ok and it runs perfectly.

How can I tell Xcode that this is all ok and not to complain about it?

Solution

  • OK, given the discussion here's what I think would solve the analyzer complaints, let you keep your formal property, and not break any memory management rules.

    Declare a read-only property:

    @property (readonly) CGContextRef cacheContext;

    Assign the ivar directly when it's created

    _cacheContext = [self allocContextWithImage:self.someImage];

    Release it in dealloc:

    - (void)dealloc
{
    CGContextRelease(_cacheContext);
    [super dealloc];
}