It seems that UISegmentedControl objects only send out "UIControlEventValueChanged" events. Is it possible to make them emit "UIControlEventTouchDown" events also ?
Have tried to right click the control in IB and then connect the "UIControlEventTouchDown" event option to an IBAction method, but no event is sent out. Have also tried to do it in code using an "action : #selector" statement but also no event.
In both cases, when I change the event to "UIControlEventValueChanged", the event is sent out as expected.
Hope that somebody who is knowledgeable on this can help ...
You could use the addGestureRecognizer: method inherited from UIView
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My view controller has UITextField object as a subview. The controller is set as target to handle the text field's UIControlEventTouchUpOutside event.
I'm trying to use this event handler for dismissing keyboard when the text field becomes first responder, but it seems to be never called. Delegate methods like textFieldShouldReturn work just fine.
Why the text field object doesn't send action message to the target? I tried this scheme for bunch of all touch events, but no luck.. Or do I have to subclass UITextField somehow to be able to catch this event?
Thanks in advance!
UITextField for sure responds to those event to handle cursor positioning and so on. It might not 'forward' those event to its parent. If you need to intercept those, you can subclass UITextEvent and catch those event yourself (of course do not forget to call [super blablabla] in order to keep the standard behavior.
Maybe It just doesn't respond the UIControlEventTouchUpOutside event. I am sure it will respond UIControlEventValueChanged event. I think you can put a transparent custom UIButtom as background view, and if any touchInSideUp in the UIButtom, you can dismissing keyboard as desired.
It responds to the same events as UIButton. Take a look in IB. Also you may consider using UITextFieldDelegate method
- (BOOL) textFieldShouldBeginEditing:(UITextField *)textField
I'm trying to set up methods to be executed when value of certain text field is changed and saved. I tried to hook up this method with Value Changed event in Iterface Builder. It doesn't respond and I use this same event with some other control/classes and it works.
There is also no delegate method usable for that purpose.
Last resort could be only UITextFieldTextDidEndEditingNotification notification or UITextFieldTextDidChangeNotification notification, but I would certainly like to avoid writing observers if simple event in interface builder serves the purpose.
Any idea?
The valueChanged event is for buttons and sliders. For TextFields you'll want to use the Editing Changed, Editing Did Begin and Editing Did End events.
If that doesn't help become a UITextFieldDelegate instead.
I want to call a method when the done button is clicked in the UITextField KeyBoard? Please Help me...
It's not even necessary to implement the delegate. I greatly prefer using good, old-fashioned target/action pattern to handle this. It can also lead to cleaner code if you have multiple ways of ending editing (say, intercepting touches outside the text field to cancel editing).
To use target/action, simply wire up UIControlEventEditingDidEndOnExit, which shows up in Interface Builder as the Did End On Exit event.
No muss, no fuss. A lot cleaner and easier than implementing the delegate.
See the UITextFieldDelegate Protocol reference. You probably want to implement the – textFieldShouldReturn: method in your delegate.
In many situations, such as making the keyboard go away when the use clicks done, there are two options: set the text field's delegate to self, and adopt the UITextFieldDelegate protocol, and then use the method
- (BOOL)textFieldShouldReturn:(UITextField *)textField;
to resignFirstResponder and return YES. But you can also
addTarget:self
action:#selector(myMethod:)
forControlEvent:UIControlEventDidEndOnExit];
or something like that, using the did end on exit event, and then in the method, [sender resignFirstResponder]. So what is the best option in situations like these: the delegate, or the event?
The quick rule of thumb is that delegates are supposed to answer the question of "should I?" on behalf of the object they are a delegate for. Events, on the other hand, are broadcast afterward to let listeners know that something has happened.
In your case, while you could call [sender resignFirstResponder] in response to the event, you're mixing metaphors by doing this. Your delegate should have already made the decision to hide the keyboard (or not) and the event being broadcast is merely to let all the other components know that they keyboard hid.
If you are going to be paired with one other class, where the real type of that class may vary, then it makes a lot of sense to formalize that pairing into a protocol and a delegate arrangement.
If the information you want to send is targeted at a broader set of objects, then it starts to make more sense to use notifications - though now you have somewhat obscured what information is being passed by the notification as there's no central definition for what to expect.
Both are about an equal load to work with - with a delegate you have to set yourself and then remember to unset yourself before you are deallocated. You have to do the same thing with notifications, remember to start listening and then unsubscribe before you are deallocated.
Also, you should try as much as possible to make sure you send notifications out on the main thread as the notices get sent on the same thread they started from. Same goes for delegate methods, it's not very kind to call a delegate method from some other mystery thread!
The delegate makes your objects more reusable they are an adapter that lets any object interact with the defined behaviors of that object and use the object. I would say delegates should be adopted by the object responsible for keeping the state of and defining behavior to actions that will occur in the object that it is using. Events should be used for any other objects that are intersted in particular action that the object that has the protocol does (so objects not responsible for keeping the state of the object that defines the protocol).
For example: A view controller using a textfield will adopt its protocol to dismiss the keyboard and any other behaviors that can occur for a textfield, maybe another controller will do some animation when the keyboard is dismissed, so it will register to the textfield as an event in order to receieve the event of the keyboard being dismissed.
I have a pretty simple UIViewController. It's initialized with a view I've created in Interaface Builder, which contains only a UIImageView. When the user touches the screen, I want the touchesBegan message of UIViewController to get called. So, I override it and added some logging, but nothing has happened.
I haven't done anything "special" at all, as since UIViewController inherits from UIResponder, I expect this to work right out of the box. From what I understand UIImageViews have user interaction disabled by default, so I have enabled it, both via InterfaceBuilder and in my UIViewcontroller's viewDidLoad method (I have tied the UIImageView to an IBOutlet). I also am ensuring that userInteraction is enabled in the parent view in Interface Builder.
Anything else that I am forgetting here?
OK, I'm a dummy. It works fine. The problem was, I didn't realize I was sending a release message to the UIViewController without having retained it elsewhere first. So that was causing the problem.
It is hard to say what your problem is, I don't know what you mean by overriding it?
Make sure you are connecting the touchesBegan event with an IBAction in Interface Builder?
You must create a IBAction function to handle the event, and explicitly connect the even to the IBAction. It is not as simple as simply overriding a method.
Although you have the View tied to an IBOutlet, you need to connect the event using an IBAction, or else you won't get any of those events.
Please ignore the first answer. It is, in fact, as easy as overriding the method in the custom view. The most common reason for not receiving touchesBegan is the canBecomeFirstResponder method not being implemented. This is not an IB hookup, these are the standard methods for touch handling.