Objective c 将对象设置为nil时不调用dealloc方法

我有个问题

我首先创建了一个扩展NSObject的对象，为description和dealloc方法提供了覆盖。这是我的Employee.m文件：

@implementation Employee
.....

-(NSString *)description
{
    return [NSString stringWithFormat:@"Employ ID: %d has $%d value of assets", [self     employeeID], [self valueOfAssets]];
}

-(void)dealloc
{   
    NSLog(@"deallocating.. %@", self);
    [super dealloc];
}

在main.m中，我首先创建了一个NSMutableArray来保存员工对象列表：

NSMutableArray *employees = [[NSMutableArray alloc] init];

for (int i =0; i< 10; i++)
{
    // Create an instance of Employee
    Employee *person = [[Employee alloc] init];

    // Give the instance varaible interesting values
    [person setEmployeeID:i];
    [employees addObject: person];
}

我希望调用每个Employee对象的

dealloc

方法，我会看到一些日志，如：

deallocating.. Employ ID 0 has value.....
deallocating.. Employ ID 2 has value.....
....

但是，我没有看到任何日志，如果我在

dealloc

方法上设置了一个断点，那么这个断点永远不会被命中

---

有什么想法吗？

释放对象的正确方法是

[employees release];

---

将其设置为

nil

不会释放内存。

由于允许您调用

[super dealloc]

，我可以假定您没有使用。这意味着您需要显式地将您编写的每个

alloc

与平衡

release

调用配对。对于您来说，当您将数组设为nil时，您实际上泄漏了员工的所有内存。你需要再次循环数组以释放它们，或者更好，因为你正在学习尽快开始编写ARC代码。

---

可能需要注意的是，ARC正是为这种情况而创建的；这对我们的大脑来说是有意义的，现在如果你使用最新的工具，它可以成为现实。

一些观察结果：

person=nil

不会释放非ARC代码中的对象。它将在ARC代码中显示（至少如果它很强的话）

在ARC中，当局部对象超出范围时，它们将自动为您释放。在非ARC中，超出范围的对象将不会为您发布（如果您在其他地方没有对这些对象的其他引用，您将最终导致泄漏）

将项添加到可变数组将增加项的保留计数，因此即使在非ARC代码中包含释放，对象也不会被释放，直到保留计数降至零（通过在将person对象添加到数组后释放person对象，并将其从数组中移除来实现）

因此，鉴于这是非ARC代码，它可能类似于：

- (void)testInNonArcCode
{
    NSMutableArray *employees = [[NSMutableArray alloc] init]; // employees retain count = +1

    for (int i =0; i< 10; i++)
    {
        //create an instance of Employee
        Employee *person = [[Employee alloc] init]; // person retain count = +1

        //Give the instance varaible interesting values
        [person setEmployeeID:i];
        [employees addObject: person];  // person retain count = +2
        [person release];  // person retain count = +1 (YOU REALLY WANT TO DO THIS OR ELSE OR NON-ARC PROGRAM WILL LEAK)
        // person = nil;   // this does nothing, except clears the local var that's limited to the for loop scope ... it does nothing to reduce the retain count or improve memory management in non-ARC code, thus I have commented it out
    }

    // do whatever you want

    [employees removeAllObjects]; // this will remove all of the person objects and they will have their respective retain counts reduced to 0, and therefore the Employee objects will be released

    [employees release]; // employees array's own retain count reduced to zero (and will now be dealloced, itself)
}

-（无效）测试非随机码
{
NSMutableArray*员工=[[NSMutableArray alloc]init]；//员工保留计数=+1
对于（int i=0；i<10；i++）
{
//创建Employee的实例
员工*person=[[Employee alloc]init]；//人员保留计数=+1
//给实例变量指定有趣的值
[person setEmployeeID:i]；
[employees addObject:person]；//person retain count=+2
[person release]；//person retain count=+1（您确实要这样做，否则非ARC程序将泄漏）
//person=nil；//除了清除限制在for循环范围内的本地变量之外，它什么都不做……它对减少非ARC代码中的保留计数或改进内存管理没有任何作用，因此我将其注释掉
}
//你想干什么就干什么
[employees removeAllObjects]；//这将删除所有person对象，并且他们各自的保留计数将减少到0，因此employees对象将被释放
[employees release]；//employees数组自身的保留计数减少为零（现在将自行解除分配）
}

在ARC代码中：

- (void)testInArcCode
{
    NSMutableArray *employees = [[NSMutableArray alloc] init]; // employees retain count = +1

    for (int i =0; i< 10; i++)
    {
        //create an instance of Employee
        Employee *person = [[Employee alloc] init]; // person retain count = +1

        //Give the instance varaible interesting values
        [person setEmployeeID:i];
        [employees addObject: person];  // person retain count = +2

        // person = nil;      // this would reduce person retain count to +1 (but unnecessary in ARC because when person falls out of scope, it will have it's retain count automatically reduced)
    }

    // do whatever you want

    [employees removeAllObjects]; // this will remove all of the person objects and they will have their respective retain counts reduced to 0, and therefore will be released

    // [employees release]; // not permitted in ARC
    // employees = nil;     // this would effectively release employees, but again, not needed, because when it falls out of scope, it will be released anyway
}

-（无效）代码
{
NSMutableArray*员工=[[NSMutableArray alloc]init]；//员工保留计数=+1
对于（int i=0；i<10；i++）
{
//创建Employee的实例
员工*person=[[Employee alloc]init]；//人员保留计数=+1
//给实例变量指定有趣的值
[person setEmployeeID:i]；
[employees addObject:person]；//person retain count=+2
//person=nil；//这会将person retain count减少到+1（但在ARC中没有必要，因为当person超出范围时，它将自动减少其retain count）
}
//你想干什么就干什么
[employees removeAllObjects]；//这将删除所有person对象，并且他们各自的保留计数将减少到0，因此将被释放
//[员工释放]；//在ARC中不允许
//employees=nil；//这将有效地释放employees，但同样不需要，因为当它超出范围时，无论如何都会释放它
}

谢谢ctrahey，我已经将我的项目转换为ARC。现在它可以工作了，我不需要再打电话给[super dealoc]问题已经通过将我的项目转换为ARC解决了：编辑>重构>转换为Objective-C ARC，有关ARC的更多信息，这应该是公认的答案。我不认为“更改为ARC”正确回答这个问题，因为这个问题意味着此人出于某种原因没有使用ARC（这可能是故意的），这个答案是解释性的，也解释了ARC会有什么不同。

- (void)testInArcCode
{
    NSMutableArray *employees = [[NSMutableArray alloc] init]; // employees retain count = +1

    for (int i =0; i< 10; i++)
    {
        //create an instance of Employee
        Employee *person = [[Employee alloc] init]; // person retain count = +1

        //Give the instance varaible interesting values
        [person setEmployeeID:i];
        [employees addObject: person];  // person retain count = +2

        // person = nil;      // this would reduce person retain count to +1 (but unnecessary in ARC because when person falls out of scope, it will have it's retain count automatically reduced)
    }

    // do whatever you want

    [employees removeAllObjects]; // this will remove all of the person objects and they will have their respective retain counts reduced to 0, and therefore will be released

    // [employees release]; // not permitted in ARC
    // employees = nil;     // this would effectively release employees, but again, not needed, because when it falls out of scope, it will be released anyway
}