objective-c - 在 Setter 中保留计数和复制？

Question

这是上一个问题的后续问题，希望更清楚一些。我只是好奇下面的代码是如何工作的，特别是变量 myString 被释放。它看起来不像是来自输出？

代码

// IMPLEMENT
@implementation CelestialBody
- (void)setName:(NSString *)newName{
    if(name != newName) {
        [name release];
        name = [newName copy];
    }
}
- (void)dealloc{
    [name release];
    name = nil;
    [super dealloc];
}
@end

.

// ------------------------------------------------------------------- **
// MAIN: 30th September 2009
// ------------------------------------------------------------------- **

#import <Foundation/Foundation.h>
#import "CelestialBody.h"

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    CelestialBody *newPlanet = [[CelestialBody alloc] init];
    NSString *myString = [[NSString alloc]initWithFormat:@"go home"];
    NSLog(@"RetainCount_1: %d",[myString retainCount]);

    [newPlanet setName: myString];
    NSLog(@"RetainCount_2: Incremented by copy in setName");    

    // Clean up
    NSLog(@"RetainCount_2: %d -Before Release",[myString retainCount]);
    [newPlanet release];
    [myString release];
    [pool drain];
    NSLog(@"RetainCount_1: %d -After Release",[myString retainCount]);
    return 0;
}
// ------------------------------------------------------------------- **

输出

Running…
2009-10-01 09:28:50.395 RetainCount_1: 1
2009-10-01 09:28:50.399 RetainCount_2: Incremented by copy in setName
2009-10-01 09:28:50.399 RetainCount_2: 2 -Before Release
2009-10-01 09:28:50.400 RetainCount_1: 1 -After Release
Debugger stopped.

我目前正在重读《内存管理指南》，尝试看看我错过了什么。

非常感谢

编辑

刚刚添加了一个释放到dealloc，看起来这就是我所缺少的。

- (void)dealloc{
    [name release];
    name = nil;
    [super dealloc];
}

加里

Answer 1

is the variable myString getting released.

[myString release];

所有迹象都表明是。

It does not look like it is from the output?

NSLog(@"RetainCount_2: %d",[myString retainCount]);
[myString release];

您的 NSLog 语句的输出不会反射(reflect) release 消息，因为 release 消息尚未发生。

另外，不用担心保留计数。它们可能非常具有误导性。只要您遵循 Cocoa 的规则并且不创建任何所有权循环(A 拥有 B 拥有 C 拥有 A)，您就很少会遇到问题。