CODEWITHSUNDEEP
automatic-ref-counting
Morkrom
Morkrom

Reputation: 578

Cocoa with ARC: Setting a strong property

Simple question:

I have an AVPlayer property called player (could be any strong property, its just AVPlayer for example's sake).

If it has already been allocated (and is not nil) and I re-allocate it without setting it to nil:

self.player = [[AVDelegatingPlayer alloc] initWithURL:[NSURL URLWithString:urlString]];

Are there memory implications for this in an ARC environment?

Upvotes: 0

Views: 32

Answers (1)

Kazuki Sakamoto
Kazuki Sakamoto

Reputation: 13999

Take a look at clang source code for storing an object into a __strong variable.

https://github.com/llvm-mirror/clang/blob/master/lib/CodeGen/CGObjC.cpp#L2108-L2119

// Retain the new value.
newValue = EmitARCRetain(type, newValue);

// Read the old value.
llvm::Value *oldValue = EmitLoadOfScalar(dst, SourceLocation());

// Store.  We do this before the release so that any deallocs won't
// see the old value.
EmitStoreOfScalar(newValue, dst);

// Finally, release the old value.
EmitARCRelease(oldValue, dst.isARCPreciseLifetime());

So your code would be compiled as the following.

id newValue = [[AVDelegatingPlayer alloc] initWithURL:[NSURL URLWithString:urlString]];
id oldValue = self.player;
self.player = newValue;
[oldValue release];

Upvotes: 1

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