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Re: Need advice about NSTextField, performClick IBAction, and memory man
Re: Need advice about NSTextField, performClick IBAction, and memory management
Fri, 14 Dec 2018 01:09:41 -0500
On Dec 13, 2018, at 3:55 PM, Bertrand Dekoninck wrote:
In InterfaceBuilder (not Gorm here but it should be the same), I've
also connected the "performClick" action from the textField to the
addButton, so that the createTask method is also called when I type
on the "Enter" key of the keyboard after editing the textField.
It works as expected, but I've got extra calls to createNewTask :
when the textField has the focus, performClick is also sent when
clicking on another widget or if I use the "tab" key to cycle into
Is there a way to avoid these ?
You can set the textfield to only send its action when Enter's
pressed (instead of every time editing finishes): In Interface
Builder, select the textfield, then show the Inspector panel. Under
the Inspector's Attributes tab, switch the textfield's 'Send Action'
mode from "End editing" to "Enter only". (You can also do this
programmatically by sending the textfield's cell a
2) The second problem is a memory management problem : in the
createNewTask, I create a NSString using alloc +init.
If I release that string at the end of the method, I've got a
segfault if I try to add more than two tasks in the tasklist
These three lines in createNewTask: cause the issue:
NSString *string = [[NSString alloc] init];
string = [textField stringValue];
[string release];// With this, I've got an "exec_BAD_ACCESS" error
when calling three times in a row createNewTask with the same string
The first line sets 'string' to a retained, empty string object.
The next line sets 'string' to the object returned by [textField
stringValue], leaking the previous string object (its address was
forgotten while it was still retained). 'String' then points to an
object that wasn't retained by your code, so sending it a release
message will cause it to deallocate while it's still referenced
elsewhere (segfaulting if it's accessed after that).
You can fix the issue by removing the first & third lines (empty-
string allocation, release call), and moving the 'string' var
definition to the second line:
NSString *string = [textField stringValue];
- Need advice about NSTextField, performClick IBAction, and memory management, Bertrand Dekoninck, 2018/12/13
- Re: Need advice about NSTextField, performClick IBAction, and memory management,
Josh Freeman <=
- Re: Need advice about NSTextField, performClick IBAction, and memory management, David Chisnall, 2018/12/14
- Re: Need advice about NSTextField, performClick IBAction, and memory management, Riccardo Mottola, 2018/12/14
- Re: Need advice about NSTextField, performClick IBAction, and memory management, Bertrand Dekoninck, 2018/12/14