static int gCounter;
@implementation Fraction
+(Fractoin *)allocF
{
extern int gCounter;//由于gCounter定义在该文件中，此行定义可省略；
++gCounter;
return [Fraction alloc];
}
+(int)count
{
extern int gCounter;//由于gCounter定义在该文件中，此行定义可省略；
return gCounter;
}
@end
#import "Fraction"
int main (int argc, char *argv[])
{
@autoreleasepool{
Fraction *a, *b, *c;
NSLog(@"Fractions allocted: %i", [Fraction count]);
a = [[Fraction allocF] init];
b = [[Fraction allocF] init];
c = [[Fraction allocF] init];
NSLog(@"Fractions allocted: %i", [Fraction count]);
}
return 0;
}
输出：
Fraction allocated:0
Fraction allocated:3