NSString和UIAlertView有问题

Question

当使用这个UIAlertView时，我有一个很奇怪的问题。在看医生时，他们有几个办公室。选择一个后，你会看到一个警报，可以调用这个位置或者在地图上显示它。要创建警报并在警报解除时准备好数据，我在头文件中声明了4个NSString（尽管我可能只需要2个）。 （alertTitle，alertText，alertNumber和alertAddress）

查看代码时，问题是涉及到alertAddress的位置。还要记住alertNumber。我有很多这样的代码被压缩了，但是已经扩展了它来帮助我自己找到问题！

-(IBAction)address1ButtonPressed:(id) sender { 
     Formatter *pnf = [Formatter alloc]; 
     alertTitle = [physician objectForKey:ADDRESS1DESC_KEY]; 
     NSString *a = [physician objectForKey:ADDRESS1A_KEY]; 
     NSString *b =[physician objectForKey:ADDRESS1CITY_KEY]; 
     NSString *c =[physician objectForKey:ADDRESS1STATE_KEY]; 
     NSString *d = [physician objectForKey:ADDRESS1ZIP_KEY]; 
     NSString *p = [physician objectForKey:PHONE1A_KEY]; 
     alertAddress = [[NSString stringWithFormat:@"http://maps.google.com/maps?q=%@,+%@,+%@+%@",a,b,c,d] stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; 
     NSLog(@"%@",alertAddress); 
     alertText = [NSString stringWithFormat:@"%@\n%@, %@ %@\n%@",a,b,c,d,[pnf stringFromPhoneNumber:p]]; 
     alertNumber = [p stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]; 
     [pnf release]; 
     UIAlertView *phoneAlert = [[UIAlertView alloc] initWithTitle:alertTitle message:alertText delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Call",@"View Map",nil]; 
     [phoneAlert show]; 

     } 

一切都很好，直到我们到达处理警戒解雇的地步。 alertNumber似乎遇到了很好，我可以用它来触发电话并将其登录到控制台。

但是，alertAddress并不乐意做同样的事情。即使尝试将其记录到控制台也会导致EXC_BAD_ACCESS。 alertAddress在涉及警报之前正确记录数据，但在处理警报按钮解除时访问此数据会导致问题。我甚至使用alertNumber它是地方和代码完美的功能。

为什么两个完全相同的NSString变量在使用完全相同的方式时行为如此不同？

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex { 
    if (buttonIndex == 1) { 
     NSLog(@"Dialing: %@",alertNumber); 
     [[UIApplication sharedApplication] openURL:[NSURL URLWithString:[NSString stringWithFormat:@"tel://%@",alertNumber]]];  
    } 
    if (buttonIndex == 2) { 
     NSLog(@"Map Selected"); 
     NSLog(@"alertAddress contains: %@",alertAddress); 
     [[UIApplication sharedApplication] openURL:[NSURL URLWithString:[NSString stringWithFormat:@"http://maps.google.com/maps?q=%@",alertAddress]]];  
    } 
} 

下面是在头文件过相关声明...

@interface PhysicianDetailViewController: UIViewController { 
    ... 
    NSString *alertTitle; 
    NSString *alertText; 
    NSString *alertNumber; 
    NSString *alertAddress; 
... 
} 

@property (nonatomic, retain) NSString *alertTitle; 
@property (nonatomic, retain) NSString *alertText; 
@property (nonatomic, retain) NSString *alertNumber; 
@property (nonatomic, retain) NSString *alertAddress; 
... 

这里是在这个过程中是否有帮助控制台输出....

> 2010-10-29 11:09:17.954 [2672:307] http://maps.google.com/maps?q=123%20Main%20Street%0ASuite%20A,+Tampa,+FL+11111 
    > 2010-10-29 11:09:21.657 [2672:307] Map Selected 
    > Program received signal: “EXC_BAD_ACCESS”. 
    > kill quit 

Answer 1

使用setter，所以实例将被保留。当你不再需要它时，请记住释放它。

self.alertAddress = [[NSString stringWithFormat:@"http://maps.google.com/maps?q=%@,+%@,+%@+%@",a,b,c,d] stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; 

与其他属性一样。

的另一件事是，它似乎你有内存泄漏：

UIAlertView *phoneAlert = [[UIAlertView alloc] initWithTitle:alertTitle message:alertText delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Call",@"View Map",nil]; 
[phoneAlert show]; 
//add release after showing alert 
[phoneAlert release];