Can't set BecomeFirstResponder in EditingDidEnd Action - cocoa-touch

Question

I am trying to do Error Checking for a Correct Time in a UItextField. I didn't want an error to pop up while the user is typing (To give them the chance to fix it first) so I thought I would do the Check during an EditingDidEnd Action. I setup ones for Hours, Minutes and Seconds. Here is the code I tried for inHours:
- (IBAction)inHourEditEnd:(id)sender
{
// Check to make sure value is between 0 & 23 Hours
if ([[[self inHour] text] intValue] >= 0 && [[[self inHour] text] intValue] < 24) {
[self updateDuration];
} else {
NSString *errorDescription = [NSString stringWithFormat:#"%# hours is not a valid start time. Please enter an hour between 0 and 23", [[self inHour] text]];
UIAlertView *errorMessage = [[UIAlertView alloc] initWithTitle:#"Ivalid Hour for Start Time"
message:errorDescription
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[errorMessage show];
[_inHour becomeFirstResponder];
}
}
The alert works fine but it won't go back to the textfield (inHour) after showing the alert.
It just stays on whatever textField I tapped to cause EditingDidEnd. Searching here I found a way to make the alertView send the user back to the right textbox using this code:
- (void)alertView:(UIAlertView *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
//Checks For Approval
if (buttonIndex == 0) {
[_inHour becomeFirstResponder];
}
}
But this will only work for the first box and I need to make it work with inHour, inMinute and inSeconds.
Any Suggestions how I can make this work?
Is either one of these paths in the right direction?
Thank you for any help.

Answer 1

If you really want to do your validation after the text field has already lost first responder status, you could add a property to your view controller to track the text field that needs to receive becomeFirstResponder:
// in your .m file, declare a class extension for "private" members
#interface MyViewController ()
#property (weak, nonatomic) UITextField *lastValidationFailureField;
#end
// add this to inHourEditEnd:
self.lastValidationFailureField = _inHour;
// use this property in alertView:clickedButtonAtIndex:
[self.lastValidationFailureField becomeFirstResponder];
self.lastValidationFailureField = nil;
Alternatively, you could prevent the user from leaving the text field. Have your view controller implement UITextFieldDelegate and set all of your text fields’ delegate outlets to your view controller. Then implement textFieldShouldEndEditing:
- (BOOL)textFieldShouldEndEditing:(UITextField *)textField
{
if (textField == [self inHour]) {
if ([[textField text] intValue] >= 0 && [[textField text] intValue] < 24) {
[self updateDuration];
} else {
NSString *errorDescription = ...
UIAlertView *errorMessage = ...
[errorMessage show];
// prevent the text field from even losing first responder status
return NO;
}
}
if (textField == [some someOtherTextFieldToValidate)] {
...
}
return YES;
}
I put all of the logic in a single method here for brevity, I would recommend at least some minimal refactoring of that code if you have more than a couple of text fields to validate.
You would not need your actions method such as inHourEditEnd: any more.