objective-c 2.0 properties and 'retain'
- by Adam
Stupid question, but why do we need to use 'retain' when declaring a property? Doesn't it get retained anyway when it's assigned something?
Looking at this example, it seems that an object is automatically retained when alloc'ed, so what's the point?
#import "Fraction.h"
#import <stdio.h>
int main( int argc, const char *argv[] ) {
Fraction *frac1 = [[Fraction alloc] init];
Fraction *frac2 = [[Fraction alloc] init];
// print current counts
printf( "Fraction 1 retain count: %i\n", [frac1 retainCount] );
printf( "Fraction 2 retain count: %i\n", [frac2 retainCount] );
// increment them
[frac1 retain]; // 2
[frac1 retain]; // 3
[frac2 retain]; // 2
// print current counts
printf( "Fraction 1 retain count: %i\n", [frac1 retainCount] );
printf( "Fraction 2 retain count: %i\n", [frac2 retainCount] );
// decrement
[frac1 release]; // 2
[frac2 release]; // 1
// print current counts
printf( "Fraction 1 retain count: %i\n", [frac1 retainCount] );
printf( "Fraction 2 retain count: %i\n", [frac2 retainCount] );
// release them until they dealloc themselves
[frac1 release]; // 1
[frac1 release]; // 0
[frac2 release]; // 0
¦output
Fraction 1 retain count: 1
Fraction 2 retain count: 1
Fraction 1 retain count: 3
Fraction 2 retain count: 2
Fraction 1 retain count: 2
Fraction 2 retain count: 1
Deallocing fraction
Deallocing fraction
This is driving me crazy!
