NSIndexSet not set when user press enter after NSAlert - objective-c

Question

I have a very simple Mac app, that at one particular time, a button brings up a NSAlert with an input field. After that I take some actions on a NSTableView.
It works fine if the user presses the OK button, but if the user presses ENTER, it does not define the selectedrows
NSAlert *alert = [[NSAlert alloc] init];
[alert setMessageText:#"Damage"];
[alert addButtonWithTitle:#"Ok"];
[alert addButtonWithTitle:#"Cancel"];
NSInteger damage = 0;
NSTextField *input = [[NSTextField alloc] initWithFrame:NSMakeRect(0, 0, 200, 24)];
[input setStringValue:#""];
[[alert window]setInitialFirstResponder:input];
[alert setAccessoryView:input];
NSInteger button = [alert runModal];
if (button == NSAlertFirstButtonReturn) {
damage = [input integerValue];
} else if (button == NSAlertSecondButtonReturn) {
}
//data
NSIndexSet *set = [self.tableView selectedRowIndexes];
NSUInteger index = [set lastIndex];
The index has the value of NSNotFound.
Could someone help fix it?
Tks

Answer 1

So, I basically needed to add a key equivalent to the ENTER and it solved the issue:
NSAlert *alert = [[NSAlert alloc] init];
[alert setMessageText:#"Damage/Heal"];
[alert addButtonWithTitle:#"Ok"];
[alert addButtonWithTitle:#"Cancel"];
NSInteger damage = 0;
NSTextField *input = [[NSTextField alloc] initWithFrame:NSMakeRect(0, 0, 200, 24)];
[input setStringValue:#""];
[[alert window]setInitialFirstResponder:input];
[alert setAccessoryView:input];
alert.buttons[0].keyEquivalent=#"\r";//new code
NSInteger button = [alert runModal];
if (button == NSAlertFirstButtonReturn) {
damage = [input integerValue];
} else if (button == NSAlertSecondButtonReturn) {
}