How to disable alertview's button in iPhone? - iphone

Question

I have alert view having 2 buttons "OK" and "Cancel" and a textfield.
Now i want to disable "OK" button until user enter some text in textfield.
How can i do this?
thanks in advance

Answer 1

UPDATE 2: For Swift 5.1
<#your alert controller#>.addTextField {(tf) in
//... set your tf characteristics i.e .keyboardType here
NotificationCenter.default.addObserver(forName: UITextField.textDidChangeNotification,
object: tf,
queue: OperationQueue.main) { _ in
//enable or disable the selected action depending on whether the textField text is empty
<#your alert controller#>.actions[0].isEnabled = !tf.text!.isEmpty
}
}
posting this to update the response since ios 5 :
- (BOOL)alertViewShouldEnableFirstOtherButton:(UIAlertView *)alertView
{
UITextField *textField = [alertView textFieldAtIndex:0];
if ([textField.text length] == 0)
{
return NO;
}
return YES;
}
UPDATE:iOS 8 Since Apple have deprecated the UIAlertView in favour of the UIAlertController. There is no longer a delegate call to alertViewShouldEnableFirstOtherButton:
So instead you would set the buttons enabled property via the UITextFieldTextDidChangeNotification
Add a textView to the alert with
(void)addTextFieldWithConfigurationHandler:(void (^)(UITextField *textField))configurationHandler
[<#your alert#> addTextFieldWithConfigurationHandler:^(UITextField *textField) {
textField.delegate = self;
textField.tag = 0; //set a tag to 0 though better to use a #define
}];
Then implement the delegate method
(void)textFieldDidBeginEditing:(UITextField *)textField
- (void)textFieldDidBeginEditing:(UITextField *)textField{
//in here we want to listen for the "UITextFieldTextDidChangeNotification"
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(textFieldHasText:)
name:UITextFieldTextDidChangeNotification
object:textField];
}
When the text in textField changes it will invoke a call to "textFieldHasText:" and pass along a NSNotification*
-(void)textFieldHasText:(NSNotification*)notification{
//inside the notification is the object property which is the textField
//we cast the object to a UITextField*
if([[(UITextField*)notification.object text] length] == 0){
//The UIAlertController has actions which are its buttons.
//You can get all the actions "buttons" from the `actions` array
//we have just one so its at index 0
[<#your alert#>.actions[0] setEnabled:NO];
}
else{
[<#your alert#>.actions[0] setEnabled:YES];
}
}
Don't forget to remove your observer when done

Answer 2

I wanted to extend the answer by Ryan Forsyth by adding this. If you add a Default styled UIAlertView, you can get an out of range exception if you try to access a textfield as none exist, so check your view style first.
-(BOOL)alertViewShouldEnableFirstOtherButton:(UIAlertView*)alertView
{
if(alertView.alertViewStyle == UIAlertViewStyleLoginAndPasswordInput ||
alertView.alertViewStyle == UIAlertViewStylePlainTextInput ||
alertView.alertViewStyle == UIAlertViewStyleSecureTextInput)
{
NSString* text = [[alertView textFieldAtIndex:0] text];
return ([text length] > 0);
}
else if (alertView.alertViewStyle == UIAlertViewStyleDefault)
return true;
else
return false;
}

Answer 3

You can create two buttons for Ok and Cancel.Then add those two as sub views in the UIAlertView.Now by checking the text(text length) in the textfield,You can perform enable and disable actions.

Answer 4

Without knowing the context of your application, the following may not apply - but have you read the iOS Human Interface Guidelines? It sounds as though you may be better off finding an alternative to UIAlertView if this is something that's going to be displayed to the user often.

Answer 5

Not really related to your question, but do not modify default UIAlertView if you don't want your app to be rejected. If I'm not wrong, you're adding textfields to the alertview, don't you? Like a login view. You should create your own view.
So, regarding your question, create your view, set the buttons has disabled, and delegate the UITextFields. When
- (void)textFieldDidBeginEditing:(UITextField *)textField;
is called, enable those buttons.