Weird interaction between UITextField textFieldShouldEndEditing and leftView - ios

Question

I'm finding a weird behaviour when I add a leftView (or righView) to a UITextField, then return NO to textFieldShouldEndEditing and dealocate the view controller, when trying to access the view controller again (a new instance, one would think), some times I get an EXC_BAD_ACCESS, and other times the text field is simply unresponsive.
I have no idea why this is happening, so I'm posting below the steps to reproduce.
Start with a very simple project with a Navigation Controller and 2 View Controllers, the first one has just a button to go to the second one, and the second one just have a UITextField.
The UIViewController of this second controller is the UITextField delegate:
#interface ViewController () <UITextFieldDelegate>
#property (nonatomic, weak) IBOutlet UITextField *textField;
#end
#implementation ViewController
- (void)dealloc {
NSLog(#"Dealocating View Controller");
}
- (BOOL)textFieldShouldEndEditing:(UITextField *)textField {
textField.leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];
textField.leftViewMode = UITextFieldViewModeAlways;
return NO;
}
#end
Now go to the second view controller, you can edit the text field with no problem, but cannot stop editing (as expected), but you CAN go back to the first view controller (at this point the second view controller is dealocated, as testified on the console).
But now if you again go into the second view controller (a new instance, I would expect, since the other one was deallocated), you'll find you can no longer interact with the text field.
Why is this happening? What am I doing wrong?
Notes
If I return YES to textFieldShouldEndEditing, everything works fine; but I want to keep the user on the text field until they enter a valid text.
If I don't add a leftView, everything works fine; but I want to give the user a visual feedback as to why the text field is not allowing them to leave.
Edit in response to Teja Nandamuri
I updated the view controller code to try and make sure the textField resigned first responder before the view controller get deallocated, but even with these changes, upon reentering the textField is unresponsive:
#interface ViewController () <UITextFieldDelegate>
#property (nonatomic, weak) IBOutlet UITextField *textField;
#end
#implementation ViewController
- (void)dealloc {
NSLog(#"Dealocating View Controller");
}
- (BOOL)textFieldShouldEndEditing:(UITextField *)textField {
if (textField == self.textField && ![textField.text isEqualToString:#"bien"]) {
textField.leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];
textField.leftViewMode = UITextFieldViewModeAlways;
return NO;
}
return YES;
}
- (void)textFieldDidEndEditing:(UITextField *)textField {
if ([textField isFirstResponder]) {
[textField resignFirstResponder];
}
}
#end

Answer 1

Please note that even you return NO, the UIKit will end the editing while leaving from the second controller.
Consider this case, you return NO to prevent the user moving to another control, this works as long as you stay in the same controller. If you move away from it, everything gets deallocated and when you comeback again, the textField will get instantiated again, and UIkit thinks the new textfield is a different one and will not allow the new textField to becomeFirstResponder, since the old one did not resign its responder. So you cannot edit the new textField.
Adding the leftView will not make a difference here.The only thing matter is the delegate method to return YES .Because you cannot control UIkit, and it expects you to return YES, so modify your delegate method:
- (BOOL)textFieldShouldEndEditing:(UITextField *)textField {
if (your-condition) {
textField.leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];
textField.leftViewMode = UITextFieldViewModeAlways;
return NO;
}
return YES;
}
This case works as long as you are in the second View controller. Anyway the problem still exists if you leave from the second controller, and the delegate method returns NO, you should stop user from going back to first view controller if your text field condition is not met.