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这是在杀死我!

我有一个看法。在 .h 文件中,我这样做:

@interface SearchLogs : UIViewController <UITableViewDelegate, UITableViewDataSource, UITextFieldDelegate, UIActionSheetDelegate, UIPickerViewDelegate> {

NSString *startDate;
NSDateFormatter *thisFormatter;
}


@property (nonatomic, retain) NSString *startDate;
@property (nonatomic, retain) NSDateFormatter *thisFormatter;
@end

@interface 和@properties 中还有其他内容……但这就是我要做startDate的。

在 .m 文件中,我这样做:

@implementation SearchLogs

@synthesize startDate;
@synthesize thisFormatter;

 - (void)viewDidLoad {
  NSLog(@"viewDidLoad\n");
  [super viewDidLoad];

 thisFormatter = [[NSDateFormatter alloc] init];
[thisFormatter setDateFormat:@"yyyy-MM-dd"];

  NSDate *today = [[NSDate alloc] init];
  NSLog(@"startDate refcount: '%i'\n",[startDate retainCount]);
  startDate = [thisFormatter stringFromDate:today];
  NSLog(@"startDate refcount: '%i'\n",[startDate retainCount]);
  [today release];
 }


- (void)viewWillAppear:(BOOL)animated {
 NSLog(@"viewWillAppear\n");
 [super viewWillAppear:animated];
 NSLog(@"startDate refcount: '%i'\n",[startDate retainCount]);
}


- (void)viewDidAppear:(BOOL)animated {
 NSLog(@"viewDidAppear\n");
 [super viewDidAppear:animated];
 NSLog(@"startDate refcount: '%i'\n",[startDate retainCount]);

}

#pragma mark -
#pragma mark Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
 NSLog(@"numberOfSectionsInTableView\n");
 // Return the number of sections.
 NSLog(@"startDate refcount: '%i'\n",[startDate retainCount]);   
 return 6;

}

- (void)dealloc {

[startDate release];
 [thisFormatter release];

}

这是我的问题:我的应用程序在numberOfSectionsInTableView

这是日志:

2010-06-20 17:35:22.363 cConnect[10529:207] viewDidLoad
2010-06-20 17:35:22.376 cConnect[10529:207] startDate refcount: '0'
2010-06-20 17:35:22.378 cConnect[10529:207] startDate refcount: '1'
2010-06-20 17:35:22.378 cConnect[10529:207] viewWillAppear
2010-06-20 17:35:22.379 cConnect[10529:207] startDate refcount: '1'
2010-06-20 17:35:22.379 cConnect[10529:207] viewDidAppear
2010-06-20 17:35:22.380 cConnect[10529:207] startDate refcount: '1'
2010-06-20 17:35:22.381 cConnect[10529:207] numberOfSectionsInTableView
2010-06-20 17:35:22.381 cConnect[10529:207] *** -[CFString retainCount]: message sent to deallocated instance 0x5da5730

我的主要问题是为什么? startDate从未在我的代码中明确发布。有什么我正在做的事情导致它在不知情的情况下被释放吗?

TIA

轻微编辑:

我尝试更换:

startDate = [thisFormatter stringFromDate:today];

和:

startDate = [[thisFormatter stringFromDate:today] retain];

它不再崩溃!我认为 NSDateFormatter 一直存在,直到变量不再需要它...... :(我误解了便利方法吗?

4

2 回答 2

6

你的问题是

 startDate = [thisFormatter stringFromDate:today];

这为您提供了一个自动释放的字符串。你必须保留它。要么使用

startDate = [thisFormatter stringFromDate:today];
[startDate retain];

或者使用该属性并调用设置器:

self.startDate = [thisFormatter stringFromDate:today];
于 2010-06-21T00:59:05.027 回答
1

您需要在 viewDidLoad 中使用 self.startdate 设置开始日期 - 这样您将调用访问器并在 @property 语句中使用保留。没有它,您只是直接设置一个值,并且由于它是一个自动释放的对象,您在 numberOfSectionsInTableView 发生之前就会丢失它。

于 2010-06-21T00:55:53.873 回答