即使属性设置为保留，也会出现BAD ACCESS错误 [英] BAD ACCESS error even though property is set to retain

问题描述

我希望有人能告诉我为什么我错了。以下是我的代码片段：

  TimeLogAppDelegate * appDelegate =（TimeLogAppDelegate *）[[UIApplication sharedApplication] delegate]; 
 
 PickFromListViewController * pl = [[PickFromListViewController alloc] initWithNibName：@PickListbundle：nil]; 
 pickList = pl; 
 [pickList setSearchItems：[appDelegate tableListMutableArray：type]：NSLocalizedString（type，nil）]; 
 pickList.callingViewController = self; 
 [pl release]; 
 pickList.responseSelector = [[type lowercaseString] stringByAppendingString：@Selected：]; 
 pickList.includeNone = YES; 
 pickList.includeNew = YES; 
 [self.navigationController pushViewController：pickList animated：YES]; 
  

正如你所看到的，我正在发布一半，只是为了解决这个问题。 'pickList'显然是一个PickFromListViewController并在Header中声明。我将其设置为属性（@property（非原子，保留）PickFromListViewController * pickList;）并且我@synthesize它。

我的问题是：

$在释放pl之后，我得到一个BAD ACCESS错误，访问pickList，指示指针不再可用，但我认为pickList是合成的，它会被保留，直到我发布它为止dealloc？

有人可以告诉我为什么我错了吗？

非常感谢

解决方案

将 pickList 属性设置为（非原子，保留）仅在您通过属性访问者访问该属性时才适用，如下所示：

  self.pickList = P1; 
  

或

  [self setPickList：P1]; 
  

如果您只是为成员变量赋值：

  pickList = P1; 
  

您绕过属性访问器方法，因此没有保留消息已发送。

I hope someone can tell me why I'm wrong. Here is a snippet of my code:

TimeLogAppDelegate *appDelegate = (TimeLogAppDelegate *)[[UIApplication sharedApplication] delegate];

PickFromListViewController * pl = [[PickFromListViewController alloc] initWithNibName:@"PickList" bundle:nil];
pickList = pl;
[pickList setSearchItems:[appDelegate tableListMutableArray:type ] :NSLocalizedString(type,nil)];
pickList.callingViewController = self;
[pl release];
pickList.responseSelector = [[type lowercaseString] stringByAppendingString: @"Selected:"];
pickList.includeNone = YES;
pickList.includeNew = YES;
[self.navigationController pushViewController:pickList animated:YES];

As you can see, I am releasing pl half-way through, just to create the problem. 'pickList' is obviously a PickFromListViewController and is declared in the Header. I set it up as a property (@property (nonatomic, retain) PickFromListViewController *pickList;) and I @synthesize it.

My problem is:

after pl is release I get a BAD ACCESS error accessing pickList indicating that the pointer is no longer available, but I thought the fact that pickList is synthesized, it would be retained until I release it at dealloc?

Can someone tell me why I am wrong?

Many thanks

解决方案

Setting up your pickList property as (nonatomic, retain) only applies if you access the property via a property accessor, as follows:

self.pickList = P1;

or

[self setPickList:P1];

If you simply assign a value to the member variable:

pickList = P1;

You are bypassing the property accessor methods, so no retain message is sent.

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