> On May 20, 2020, at 7:03 AM, Gabriel Zachmann via Cocoa-dev > <cocoa-dev@lists.apple.com> wrote: > > This line is in a method I declared like that: > > - (void) loadNextImageWithIndex: (unsigned long) next_index image: > (CGImageRef *) next_image > withProps: (CFDictionaryRef *) next_props
Off-topic, but that's an odd signature. Wouldn't it be clearer to return the CFDictionaryRef instead of making it an 'out' parameter? > The caller then makes a copy of next_props for later use, and CFRelease's > next_props. > (That copy is also released later.) The "copy" may be the same object. In CoreFoundation and Foundation, if you copy an immutable object, you just get back a new reference to the same object. Same effect, but it saves memory and time. So the leaky code may be in whatever's managing that copy you made. > So it is unclear to me why the Leaks tool thinks that the above line leaks > memory. Leaks can be hard to track down; I sympathize. Avoiding CF objects as much as possible helps. Recall that an NSDictionary* is the same as a CFDictionaryRef. You can use bridge casts to convert, and if the CF ref needs to be released later, you can call CFBridgingRelease which casts and autoreleases in one operation. Another useful but not-well-known function is CFAutorelease, which is the equivalent of pre-ARC Obj-C `autorelease`. You basically call it instead of CFRelease; but you can call it immediately and keep using the object, because autorelease just promises that the object will be released sometime later. —Jens _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
