In my app, I have a UITableViewController which loads calculated data from my Core Data store. This can take quite some time and hangs the main thread, so to give the user visual feedback, I have installed the MBProgressHUD widget which will show a progress indicator (just the spinning wheel) while the calculation method runs in a separate thread.
This is fine, except that the user can still exit the UITableViewController if they think it's taking too long. Of course, this is a good thing, except that when the separate thread concludes its operation, it still tries to call its delegate (the UITableViewController) to hide the MBProgressHUD. This causes a crash because since the user already exited the UITableViewController, it has dealloc
'd and release
'd itself.
MBProgressHUD has the following code to try to stop this:
if(delegate != nil && [delegate conformsToProtocol:@protocol(MBProgressHUDDelegate)]) {
if([delegate respondsToSelector:@selector(hudWasHidden)]) {
[delegate performSelector:@selector(hudWasHidden)];
}
}
However, my app somehow seems to still be running this inner code ( [delegate performSelector:@selector(hudWasHidden)]
) even though the UITableViewController is totally gone--causing the app to crash.
Any suggestions? I am not running with NSZombiesEnabled
.
从您的UITableViewController viewWillDisappear,viewDidDisappear或dealloc方法,设置MBProgressHUD.delegate = nil;
Once the user has exited the table controller, the delegate property of the hud points to a deallocated object (= a memory zone that could contain anything). That causes the crash when the computing thread ends and tries to send any message to the delegate.
In your table view controller dealloc
, you must set the hud delegate to nil
.
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