In my viewController viewDidload() method isFirstResponder always giving false value. Here is the
code
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(#"is first responder : %i", [self.view isFirstResponder]);
}
Can someone please help why this happening?
Subclasses can override this method to update state or perform some action such as highlighting
the selection.
A responder object only becomes the first responder if the current responder can resign first-
responder status (canResignFirstResponder) and the new responder can become first responder.
You may call this method to make a responder object such as a view the first responder. However,
you should only call it on that view if it is part of a view hierarchy. If the view’s window
property holds a UIWindow object, it has been installed in a view hierarchy; if it returns nil,
the view is detached from any hierarchy.
Here is Apple doc
Related
I am in he final step to design my application.
It Basically consists of two tableviews plus other views. Each TableView has its own TableViewController class instance.
What I would like to do is to activate the corresponding menu items when the user clicks one of the table view row. For example, I want to delete the file the user is currently selecting, so the file menu save is activated. But if he is not in the table view, I want to gray it out in the menu.
Therefore, I want to use First Responder. I added menu item, defined an action delete: in the First Responder and linked the menu item to that action. TableViewController is a subclass of NSViewController. In The TableViewController.m, I write in the init method (to insert the view controller in the responder's chain):
[self setView:_tableView];
[self setNextResponder:self.view];
[self.view.subviews enumerateObjectsUsingBlock:^(NSView *subview, NSUInteger idx, BOOL *stop) { [subview setNextResponder:self]; }];
But My method delete: doesn't get called! When the user click the tableview, it becomes the First Responder right? Then THe ViewController should receive the action.
Otherwise, What is the First Responder and how to set it?
I guess I'm missing something!
reason it doesn't work
the firstResponder is the first view, or the window, or the app itself that responds to the selectors
basically
id firstResponder = keyView;
while(![firstResponder respondsToSelector:yourSelector] && firstResponder != nil) {
firstResponder = firstResponder.superview;
}
if(!firstResponder && [keyView.window respondsToSelector:sel]) {
firstResponder = window;
}
if(!firstResponder && [application respondsToSelector:sel]) {
firstResponder = application;
}
ViewControllers are not in the responder chain and never get the selector
see https://developer.apple.com/library/ios/documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/event_delivery_responder_chain/event_delivery_responder_chain.html
solution
add the VC into the responder chain
id resp = myTableView.nextResponder;
myViewController.nextResponder = resp;
tableView.nextResponder = myViewController;
I found the solution to this problem. I just forgot to add a semicolon to my actions when I defined them in the First Responder.
SO I entered "delete" instead of "delete: " And just for this reason, my method -(void)delete:(id)sender was not called!
Thanks for your help anyway!
... I guess.
This is the situation:
here a simple method, in a view controller, where we can push a botton to go in another view:
- (IBAction)actionNext:(UIButton *)sender {
self.numeriUtiliListaViewController = [[ALCNumeriUtiliListaViewController alloc] init];
[self.numeriUtiliListaViewController.view setTag:[sender tag]];
[self.delegate vai:self.numeriUtiliListaViewController title:#"Numeri Utili"];
}
the delegate's method is:
- (void)vai:(id)view title:(NSString *)title
{
ALCParentViewController *viewController = (ALCParentViewController *)view;
viewController.delegate = self;
NSLog(#"tag: %d",[viewController.view tag]);
[self.myNavigationController pushViewController:viewController animated:YES];
}
This system works well, but the only thing is the tag that i've logged in this last method, here it was print correctly, but in the view loaded by the navigation controller, when i try to catch the value in the viewDidLoad, it's 0.
Any ideas?
Thanks in advance
Update 1 2013-01-30:
if i try to print the the tag in the viewWilAppear method of the viewcontroller pushed in the navigationcontroller, i'll give the right value... why? i don't know
Whats happening here is that in your actionNext method, when you are setting the tag of the viewController's view using : self.numeriUtiliListaViewController.view, as soon as you access the view propert of the viewController, viewDidLoad method is called in the viewController. So even before the setTag function is executed, viewDidLoad has already been executed, and it is showing tag = 0. But your viewWillAppear/viewDidAppear methods will be called only when the actual view appears and by then setTag has been executed, so it shows correct value.
Makes sense? Hope this helps
Okay so I feel like there's something obvious I'm missing in this question. I've used makeFirstResponder throughout my code to move from textField 1 to 2, 2 to 3, etc. That seems to work as I want it to, yet when the new view is loaded, I want the cursor to be in textField1, and yet the following code does not place the cursor in textField1 upon load.
- (void) awakeFromNib{
[[[self view] window] makeFirstResponder:textField1];
}
I also tried setInitialFirstResponder, and that didn't have any effect either (I don't even think that would be right.) So, is it because it is in the awakeFromNib method? Can anyone tell me what I'm missing? Thanks in advance.
EDIT - My solution was differed slightly from the accepted answer so I thought I'd post my implementation. Because the view I wanted to set the first responder for was a subview added later (think the second screen of an application wizard), I simply added a setCursorToFirstTextField method:
- (void) setCursorToFirstTextField {
[[[self view] window] makeFirstResponder:textField1];
}
And made sure to call it after I had added the subview to the custom view on the original window.
Yes, you're right about the problem being the location of the method in awakeFromNib. If you log [self.view window] in your awakeFromNib, you'll see that it's NULL. I don't know how exactly you have things set up, but I'm guessing (if this relates to your WizardController question) that you're doing an alloc initWithNibName:bundle: in another class to create your view controller and then adding that controller's view to the view hierarchy. If you throw some logs in there, it will show you that awakeFromNib in the controller class is called after the alloc init, but before the view is added as a subview, so there is no window at that time. The way I got around this problem was to create a setup method in the view controller class (with the makeFirstResponder code in it), and call it from the class where you create the controller after you add it as a subview.
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
self.wizard = [[WizardController alloc] initWithNibName:#"WizardController" bundle:nil];
[self.window.contentView addSubview:wizard.view];
[self.wizard doSetup];
}
I have a universal app, where I am sharing the same controller for a IPad and IPhone storyboard.
I have put a UILongPressGestureRecognizer on a UITableView, that when a cell is pressed on iPhone it calls an action that perform a segue:
-(IBAction)showDetail:(id)sender {
UILongPressGestureRecognizer *gesture = (UILongPressGestureRecognizer*)sender;
if (gesture.state == UIGestureRecognizerStateBegan) {
CGPoint p = [gesture locationInView:self.theTableView];
NSIndexPath *indexPath = [self.theTableView indexPathForRowAtPoint:p];
if (indexPath != nil) {
[self performSegueWithIdentifier:SEGUE_DETAIL sender:indexPath];
}
}
}
the segue is a detail view performed as a 'push'. The first thing you should notice is that the sender is an NSIndexPath, is the only way I found for passing the selected cell. Maybe there's a better solution.
Everything works fine, in a sense that the segue is performed, and before the prepareForSegue is called too.
However it happens that on iPad, I have changed the segue identifier to Popover.
Now things are working in part, the segue is performed, but prepareForSegue is not called and therefore the destination view controller is not set up as it should be.
What am I doing wrong ?
What I have discovered so far, is that with any segue identifier that is not popover these are the invocations made by iOS:
prepareForSegue (on source controller)
viewDidLoad (on destination controller)
while in popover segue the invocation order is:
viewDidLoad (on destination controller)
prepareForSegue (on source controller)
just because I put all my logic in viewDidLoad, the controller was not properly initialized, and a crash happened. So this is not exactly true that prepareForSegue is not called, the truth is that I was getting an exception, and I wrongly mistaken as prepareForSegue not getting called.
I couldn't put everything in viewWillAppear because a call to CoreData had to be made and I didn't want to check if entities were ok each time the view display.
How did I solve this ? I created another method in destination controller
-(void)prepareViewController {
// initialization logic...
}
and changing the prepareForSegue method in source controller itself:
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
MyViewController *mvc = (MyViewController*)[segue destinationViewController];
// passing variable
// with segue style other than popover this called first than viewDidLoad
mvc.myProp1=#"prop1";
mvc.myProp2=#"prop2";
// viewWillAppear is not yet called
// so by sending message to controller
// the view is initialized
[mvc prepareViewController];
}
don't know if this is expected behavior with popover, anyway now things are working.
I've noticed that the boiler plate code for Xcode's Master-Detail template (iPhone) uses the following pattern for configuring the detail VC's view:
the detail VC's setters (for properties) are overwritten in order to invoke the configureView method (configureView would update all your controls in the view, e.g., labels, etc.)
the detail VC's viewDidLoad method also invokes the configureView method
I did not follow this pattern the other day when I was trying to re-use a detail VC in my movie app, and this gave me trouble.
I don't have much experience with popovers; however, if the pattern above is used with a detail VC that is displayed inside a popover, then wouldn't the detail VC's view get configured when you set the detail VC's properties from within the prepareForSegue method?
I have a custom UIView that implements the UIKeyInput protocol and has
- (BOOL) canBecomeFirstResponder{
return YES;
}
defined in the subclass. When calling:
[customView becomeFirstResponder];
NSLog(#"is first? %i",[customView isFirstResponder]);
during a button click, it returns false, even though canBecomeFirstResponder is properly set and all of the UIKeyInput protocol functions are implemented. What other things could be blocking this view from becoming the first responder? It lives inside of a scrollView and another custom view if that helps.
Update:
I checked to see what the current first responder was with:
UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow];
UIView *firstResponder = [keyWindow performSelector:#selector(firstResponder)];
and surprisingly firstResponder was nil. So nothing seems to be hogging the events.
Did you override becomeFirstResponder?
Subclasses can override this method to update state or perform some
action such as highlighting the selection.
Followup:
Subclasses can override this method to update state or
perform some action such as highlighting the selection.
A responder object only becomes the first responder if the current
responder can resign first-responder status (canResignFirstResponder)
and the new responder can become first responder.
You may call this method to make a responder object such as a view the
first responder. However, you should only call it on that view if it
is part of a view hierarchy. If the view’s window property holds a
UIWindow object, it has been installed in a view hierarchy; if it
returns nil, the view is detached from any hierarchy.
Did you verify you meet all of the above conditions?