ios - When via a class method get an object, why before return the value, the method can put the value into AutoReleasePool? -

ios - When via a class method get an object, why before return the value, the method can put the value into AutoReleasePool? -

e.g.

method1:

-(void)method1{ id array1 = [[nsmutablearray alloc] init];//now,retaincount of array1 1 }

method2:

-(void)method2{ id array2 = [nsmutablearray array]; //now,retaincount of array2 2 }

question 1:int method2,the implementation of class method +array not utilize [alloc [init]]? why did not homecoming value directly?and set value in autoreleasepoll?

question 2:which improve (faster & more efficient) utilize between 2 way? why?

both of these statements equivalent , sec 1 doesn't add together retain count of array1. first method function assume ownership , subsequently responsible release calls later on, arc don't have worry these details.

in pre-arc days, values methods homecoming set in autorelease pools avoid premature deallocation , memory leaks. consider next cases:

-(nsarray *)emptyarray { // create homecoming value calls alloc , init. nsarray *returnarray = [[nsarray alloc] init]; homecoming returnarray; }

because there no phone call [returnarray release]; value returned method never deallocated , there memory leak. @ first may seem there no direct solution this.

-(nsarray *)emptyarray { nsarray *returnarray = [[nsarray alloc] init]; homecoming returnarray; [returnarray release]; // unreachable statement }

and

-(nsarray *)emptyarray { // create homecoming value calls alloc , init. nsarray *returnarray = [[nsarray alloc] init]; [returnarray release]; homecoming returnarray; // homecoming deallocated object }

so instead add together array autorelease pool released after time--long plenty retained whatever receiving homecoming value, still preventing memory leaks.

ios objective-c cocoa memory-management automatic-ref-counting