28、内存管理与对象复制知识详解

内存管理与对象复制知识详解

1. 自动释放示例及内存管理规则

在编程中，我们常常会遇到对象的内存管理问题。为了更好地理解这些问题，下面通过一个具体的自动释放示例来进行说明。

#import <Foundation/Foundation.h>
@interface Foo: NSObject
{
    int x;
}
@end
@implementation Foo
@end
int main (int argc, char *argv[])
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    Foo   *myFoo = [[Foo alloc] init];
    NSLog (@"myFoo retain count = %lx", (unsigned long) [myFoo retainCount]);
    [pool drain];
    NSLog (@"after pool drain = %lx", (unsigned long) [myFoo retainCount]);
    pool = [[NSAutoreleasePool alloc] init];
    [myFoo autorelease];
    NSLog (@"after autorelease = %lx", (unsigned long) [myFoo retainCount]);
    [myFoo retain];
    NSLog (@"after retain = %lx", (unsigned long) [myFoo