objective-c - 在 switch 语句中达到默认值后 EXC BAD ACCESS

Question

我有这个简单的 switch 语句:

switch ([sender tag]) {
    case 0:
        [NVAlertView showNVAlertViewFromView:self.view 
                                       title:@"STOCK NUMBER" 
                                 description:@"XXXXXXXXXXX" 
                                 cancelTitle:@"Cancel" 
                                  otherTitle:@"DONE" 
                                dismissBlock:^(BOOL canceled, NSString *description) {
                                    if (!canceled) {
                                        [newItem setObject:description forKey:@"stocknum"];
                                    }
                                }];
        NSLog(@"YOP!");
        break;

    case kDescription:
        [NVAlertView showNVAlertViewFromView:self.view 
                                       title:@"DESCRIPTION" 
                                 description:@"Enter a description here." 
                                 cancelTitle:@"Cancel" 
                                  otherTitle:@"DONE" 
                                dismissBlock:^(BOOL canceled, NSString *description) {
                                    if (!canceled) {
                                        [newItem setObject:description forKey:@"description"];
                                    }
                                }];
        break;

    case kBrandName:
        [NVAlertView showNVAlertViewFromView:self.view 
                                       title:@"BRAND NAME" 
                                 description:@"Enter a brand name here." 
                                 cancelTitle:@"Cancel" 
                                  otherTitle:@"DONE" 
                                dismissBlock:^(BOOL canceled, NSString *description) {
                                    if (!canceled) {
                                        [newItem setObject:description forKey:@"description"];
                                    }
                                }];
        break;

    case kPrice:
        [NVAlertView showNVAlertViewFromView:self.view 
                                       title:@"PRICE" 
                                 description:@"$199.99" 
                                 cancelTitle:@"Cancel" 
                                  otherTitle:@"DONE" 
                                dismissBlock:^(BOOL canceled, NSString *description) {
                                    if (!canceled) {
                                        [newItem setObject:description forKey:@"description"];
                                    }
                                }];
        break;

    default:
        NSLog(@"default");
        break;
}

每次 a 值达到默认大小写时，它都会打印出“默认”并且程序会因为 EXC BAD ACCESS 而崩溃。这是什么原因造成的？谢谢!

Answer 1

EXC_BAD_ACCESS 通常是由访问已经被释放的对象引起的。

检查此开关 block 之后行中的对象，以确保它们的保留计数 > 0。我也会检查发件人。