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POPossible scenarios of using alloc/retain/release?
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2010-07-23T02:40:29.323
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2014-11-29T03:17:08.267
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2014-11-29T03:17:08.267
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Body
I have been using ojective c for almost a week, and I am mainly a c++ coder. After I read Apple's memory management guide, I try to bring my memory usage style in c++ into objective c... I tried to conclude these scenarios, I think I won't make memory mistake if I follow these instructions. Please kindly let me know if I am wrong :) I will try not to use autorelease, personally speaking, by using autorelease, there might always be some redundent memory before certain auto release pool is drained. I will only use release, which make sure my application uses minimum memory at any time. Another thing Apple says, which I describe with my own words, is: everytime I add an retain/alloc/copy, I should add a release somewhere. Here are all the scenarios I conclude: <ol> <li>In the same function: alloc an object, use it, and release it</li> <li>In the init function of a class, alloc an object, in the dealloc function of the class, release the object</li> <li>When it's necessary to own a pointer, one should retain an input pointer in a method of a class(let's say method A), and then release the pointer in the dealloc function of the class. I found that the timing of using retain in objective c is the same to the timing of using memcpy in c/c++, so I take retain as a "memory efficient copy" If the input retained pointer is to set to a member pointer variable, then one should release the member pointer first. So in case[3], alloc in init of the class is paired with release in method A, and the retain in method A is paired with the release in dealloc</li> <li>Return a pointer as return value. Honestly speaking I never do such things when I use c++. It's OK if to return a member pointer, coz someone will take care of it: <pre><code>-(UIButton*) getTheButton() { return theButton; } </code></pre> But it's really terrible to return a pointer to a locally allocated object: <pre><code>-(UIButton*) getTheButton() { UIButton* myButton = [[UIButton alloc] init]; return myButton; //TERRIBLE! } </code></pre> Someone might say I should use autorelease in that case, but I simply want to bypass that solution by using this: I will only return member pointers, or I will not return pointers, I will only operate on given input pointers. <pre><code>-void operateOnTheButton(UIButton* button) { [button release]; button = [[UIButton alloc] init]; } </code></pre></li> </ol> So, please kindly let me know if there is any problem if I follow the memory usage instructions above. Thanks :D
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<objective-c><memory-management><retain>
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Possible scenarios of using alloc/retain/release?
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