ipad - UIActionSheet在iPad上再次出现后崩溃

Question

UIActionSheet在第二次出现后崩溃。

.H文件

..UIActionSheetDelegate>{

 UIActionSheet *popupQuery;
}
@property (nonatomic, retain) UIActionSheet *popupQuery;

.M文件

-(IBAction)showActionSheet:(id)sender {

if (popupQuery.visible) {
    NSLog(@"popupQuery isVisible");

    [popupQuery dismissWithClickedButtonIndex:-1 animated:YES];

    return;
}else{


popupQuery = [[UIActionSheet alloc] initWithTitle:@"Title" delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:@"Readibility" otherButtonTitles:@"Email URL", @"Print", nil];
popupQuery.actionSheetStyle = UIActionSheetStyleBlackOpaque;
//[popupQuery showInView:self.view];


[popupQuery showFromBarButtonItem:actionButton animated:YES];

[popupQuery release];
}
  }

Answer 1

当您从popupQuery中显示actionButton后释放它时，您将放弃对对象的所有权。如果对象被释放，那么popupQuery将指向一个释放对象，当您执行popupQuery.visible时，它可能会导致崩溃。由于您拥有它作为属性(property)，因此您可以这样做–

self.popupQuery = [[[UIActionSheet alloc] initWithTitle:@"Title" delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:@"Readibility" otherButtonTitles:@"Email URL", @"Print", nil] autorelease];

最后删除 release语句。现在，当您使用 popupQuery.visible或 self.poupQuery.visible时，该对象将有效。在这种情况下，您将拥有所有权并且可以安全地访问该对象。