Set Action Listener Programmatically in IOS - ios

Hi I have created a button programmatically. I will add this button to the navigation bar. Now I want to add a Touch Up Inside action listener to it. How do I do it? Thanks.

A UIButton is a subclass of UIControl.
All you need to do after creating an button is to set the target and action of the button. i.e.
// Create your button:
UIButton *button = // However you create your button
// Set the target, action and event for the button
[button addTarget:// the object that implements the action method, or nil if you want it to propagate up the responder chain.
action:// A selector for the method
forControlEvents:UIControlEventTouchUpInside];

Since you've added them to a navigation bar, it's slightly different, but basically the same. You will add the listener/handler at the same time you create the button(s). Here I've added << and >> to a navigation bar using the following:
UIBarButtonItem *nextButton = [[UIBarButtonItem alloc] initWithTitle:#">>" style:UIBarButtonItemStylePlain target:self action:#selector(navNextButtonPressed)];
UIBarButtonItem *prevButton = [[UIBarButtonItem alloc] initWithTitle:#"<<" style:UIBarButtonItemStylePlain target:self action:#selector(navPrevButtonPressed)];
self.navigationItem.rightBarButtonItems = [NSArray arrayWithObjects:nextButton, prevButton, nil];
and then create your handlers as normal:
#pragma mark - button handling
-(void)navNextButtonPressed
{
NSLog(#"Next pressed");
}
-(void)navPrevButtonPressed
{
NSLog(#"Prev pressed");
}

Related

Custom bar button item not performing segue

I have a right bar button item as defined in my viewDidLoad:
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
UIButton *helpButton = [UIButton buttonWithType:UIButtonTypeInfoLight];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithCustomView:helpButton ];
}
I had linked the bar button item and performed segue with identifier but it's not pushing the view. Why is that so?
- (IBAction)btnShowHelp:(id)sender {
[self performSegueWithIdentifier:#"showHelp" sender:self];
}
delete the link between your button and - (IBAction)btnShowHelp:(id)sender, change your method to - (void)btnShowHelp(id)sender, then change your code in viewDidLoad like this :
UIButton *helpButton = [UIButton buttonWithType:UIButtonTypeInfoLight];
[helpButton addTarget:self action:#selector(btnShowHelp:) forControlEvents:UIControlEventTouchUpInside];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithCustomView:helpButton ];
Turns out that btnShowHelp that was in my storyboard was already replaced by the new UIButton defined in viewDidLoad and there was no need for it.
https://developer.apple.com/reference/uikit/uibarbuttonitem/1617151-initwithcustomview?language=objc
The bar button item created by this method does not call the action method of its target in response to user interactions. Instead, the bar button item expects the specified custom view to handle any user interactions and provide an appropriate response.
I was doing [self.navigationItem.rightBarButtonItem setAction:] which I then realised I was suppose to set the action for my UIButton instead of the bar button item...
UIButton *helpButton = [UIButton buttonWithType:UIButtonTypeInfoLight];
[helpButton addTarget:self action:#selector(showHelp) forControlEvents:UIControlEventTouchUpInside];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithCustomView:helpButton ];
- (void)showHelp {
[self performSegueWithIdentifier:#"showHelp" sender:self];
}
Adding action and target to a custom Navigation BarButtonItem?

How to assign actions to UINavigationItem backBarButtonItem

I am trying to find a way to stop some of the processes within a detail controller (and let the user know that this is happening) when the back button in the navigation bar is pressed. However, I can't find a way to implement these changes when the button is pressed.
Is there a way to do this?
If you want to raise a user alert/notification before going back, you are really going to have to create your own back bar button item and assign it to self.navigationItem.leftBarButtonItem.
You need to hide the default button using:
self.navigationItem.hidesBackButton = YES;
Then add a target to your new button which does your process cleanup and raises an alert. In the alert handler, pop the controller once the user has acknowledged the alert.
The fastest and easiest way is to use custom back button like below;
-(void)viewDidLoad{
UIBarButtonItem *barButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"Back" style:UIBarButtonItemStyleBordered target:self action:#selector(actionBack)];
[self.navigationItem setBackBarButtonItem:barButtonItem];
}
-(void)actionBack{
//PopViewController
}
Like any other button.
Put this in the .m file.
- (IBAction)saveButton:(id)sender {
//actions
}
Then control drag from the UINavigationBarButton to the IBAction

Add more then one button in top navigation bar in iOS

I am currently developing a chat application and within this I have to add more then 1 left bar button in navigation bar. I am developing it using xib file.
I already added left and right bar button now I want to add 2 more in the left side of navigation bar.
UINavigationItem Class Reference having property of leftBarButtonItems and rightBarButtonItems so you can add multiple UIBarButtonItem in your navigation control using following example code:
UIBarButtonItem *FirstButton = [[UIBarButtonItem alloc]
initWithTitle:#"First"
style:UIBarButtonItemStyleBordered
target:self
action:#selector(AcionFirst:)];
UIBarButtonItem *secondButton = [[UIBarButtonItem alloc]
initWithTitle:#"Second"
style:UIBarButtonItemStyleBordered
target:self
action:#selector(AcionSecond:)];
self.navigationItem.leftBarButtonItems= [NSArray arrayWithObjects:FirstButton,secondButton,nil];
-(void)AcionFirst:(id)sender
{
//do something for first bar button
}
-(void)AcionSecond:(id)sender
{
//do something for second bar button
}

UIBarButton won't show in my UINavigationController

I want to make a simple view with a navigation bar and a table view. So I created a subclass of UINavigationController and I added a UITableView in it. My is is also the UITableViewDataSource and UITableViewDelegate. Now I want to add UIBarButton in the navigation bar but it doesn't work :
UIBarButtonItem *anotherButton = [[UIBarButtonItem alloc] initWithTitle:[[Translator instance] getTranslation:#"Back"]
style:UIBarButtonItemStylePlain
target:self.parentViewController
action:#selector(dismissFiltersModal:)];
self.navigationItem.backBarButtonItem = anotherButton;
There's no error the view is displayed but not the button. How can I do to display it?
jafar,
as Apple doc suggested you should avoid to subclass UINavigationController.
This class is not intended for subclassing.
Said this, you could follow these simply steps (some advice for you):
Create your controller (say MyController) that extends UIViewController and add the table here. Set your controller as the delegate and data source for that table. If you have created by xib you need an outlet for your table view.
[P.S. you could also subclass a UITableViewController, it has a table view its own]
In viewDidLoad of MyController customize the navigation bar.
For example
UIBarButtonItem* myButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:#selector(someSelector)];
self.navigationItem.leftBarButtonItem = myButton;
You could also customize the title.
For example
self.title = #"Your custom title";
Somewhere in your code create a UINavigationController and add as a root view controller an instance of MyController.
For example:
MyController* myCtr = // alloc-init here
UINavigationController* nc = [[UINavigationController alloc] initWithRootViewController:myCtr];
The backBarButtonItem should be set on the previous view controller, not the current one to be displayed. For example, if your you are on view A, navigate to B from it, inside B A's backBarButtonItem will be displayed, not B's.
If you just want to display an item on the left hand side of the navigation bar, you can use leftBarButtonItem instead, which will display a normal bar button on that controller. It will be rectangular, not an arrow like normal back buttons though.
How about you try this :
UIButton* backButton = [UIButton buttonWithType:101]; // left-pointing shape!
[backButton addTarget:self action:#selector(dismissFiltersModal:) forControlEvents:UIControlEventTouchUpInside];
[backButton setTitle:#"Back" forState:UIControlStateNormal];
// create button item --
UIBarButtonItem* backItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
// add to toolbar
self.navigationItem.leftBarButtonItem = backItem;

UINavigationController "back button" custom text?

The "back button" of a UINavigationController by default shows the title of the last view in the stack. Is there a way to have custom text in the back button instead?
From this link:
self.navigationItem.backBarButtonItem =
[[UIBarButtonItem alloc] initWithTitle:#"Custom Title"
style:UIBarButtonItemStylePlain
target:nil
action:nil];
As Tyler said in the comments:
don't do this in the visible view controller, but in the view
controller that you'd see if you hit the back button
You can set the text in the Interface Builder:
Select the navigation item of the ViewController that the back button would return to:
In the utilities panel attribute inspector, enter your label for the Back Button:
I would prefer this approach over setting the title in code as in the accepted answer.
Also note, you need to do this in the view controller one level up the
stack. In other words, don't do this in the visible view controller,
but in the view controller that you'd see if you hit the back button.
--Tyler
I use this:
// In the current view controller, not the one that is one level up in the stack
- (void)viewDidLoad {
[super viewDidLoad];
self.navigationController.navigationBar.backItem.title = #"Custom text";
}
I found a handy solution to this by simply setting the title of the controller before pushing another controller onto the stack, like this:
self.navigationItem.title = #"Replacement Title";
[self.navigationController pushViewController:newCtrl animated:YES];
Then, make sure to set the original title in viewWillAppear, like this:
-(void)viewWillAppear:(BOOL)animated
{
...
self.navigationItem.title = #"Original Title";
...
}
This works because the default behavior of UINavigationController when constructing the back button during a push operation is to use the title from the previous controller.
The title of the back button defaults to the previous view's title so a quick trick I use is to place the following code on the previous view's .m file.
-(void)viewWillAppear:(BOOL)animated {
// Set title
self.navigationItem.title=#"Original Title";
}
-(void)viewWillDisappear:(BOOL)animated {
// Set title
self.navigationItem.title=#"Back";
}
in your init method, add the following code:
- (id)initWithStyle:(UITableViewStyle)style {
if(self = [super init]) {
//...
UIBarButtonItem *customBackButton = [[UIBarButtonItem alloc] initWithTitle:#"Back"
style:UIBarButtonItemStylePlain
target:self
action:#selector(goBack)];
self.navigationItem.leftBarButtonItem = customBackButton;
[customBackButton release];
//...
}
return self;
}
then add a simple method, to allow viewcontroller dismissing:
-(void)goBack {
[self.navigationController popViewControllerAnimated:YES];
}
Add the following code in viewDidLoad or loadView
self.navigationController.navigationBar.topItem.title = #"Custom text";
I tested it in iPhone and iPad with iOS 9
Adding to rein's answer. Note from Apple's docs that the declaration of backBarButtonItem is this:
#property(nonatomic, retain) UIBarButtonItem *backBarButtonItem
Therefore, rein's answer will leak memory because the synthesized setter will retain the instance you pass it, which is never released explicitly. You can remedy this by using autorelease
self.navigationItem.backBarButtonItem =
[[[UIBarButtonItem alloc] initWithTitle:#"Custom Title"
style:UIBarButtonItemStyleBordered
target:nil
action:nil] autorelease]; //<-- autoreleased
Or you could point a variable at the instance so you can explicitly release it later:
UIBarButtonItem* item = ...
self.navigationItem.backBarButtonItem = item;
[item release];
Hope this helps!
- (void)viewDidLoad {
[super viewDidLoad];
UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:#"Back" style:UIBarButtonItemStylePlain target:nil action:nil];
self.navigationItem.backBarButtonItem = backButton;
[backButton release];
}
I've discovered something interesting.
If you subclass the UINavigationController and override the pushViewController:animated: method and do something like this: (bear in mind that I'm using ARC)
UIBarButtonItem *backButton = [[UIBarButtonItem alloc]
initWithTitle: #"Back"
style: UIBarButtonItemStyleBordered
target: nil action: nil];
viewController.navigationItem.backBarButtonItem = backButton;
[super pushViewController:viewController animated:animated];
Then for all ViewControllers that are pushed with your navigation controller will have the "Back" button in them automatically. If you want to change the text for certain view controllers you can try and maybe cast the viewcontroller to a certain class or your own custom protocol (which your viewcontroller inherits from which could have a method like backButtonText or something silly like that) which can give you certain information on the viewcontroller that's coming in sothat you can customize the back button text for it. Now the back button text is taken care of in a place which should hold the responsibility solely. I have to admit that creating a new button to change the text sucks, but oh well.
Can anyone think of a reason why not to do it like this? Atleast you don't have to fiddle with viewcontroller titles or have to remember to create a new back button before pushing the viewcontroller on the navigation controller.
rein's answer works well.
Note that if you push more than one view controller, the changed back button title will appear for each of them, which may not be what you want.
In that case, you'll need to create the custom UIBarButtonItem each time you push a view controller.
Also, make sure you do it before pushing the view controller, otherwise you will get a screen hiccup as the title changes.
Expanding on Aubrey's suggestion, you can do this in the child view controller:
create two variables for storing the old values of the parent's navigationItem.title and the parent's navigationItem
UINavigationItem* oldItem;
NSString* oldTitle;
in viewDidLoad, add the following:
oldItem = self.navigationController.navigationBar.topItem;
oldTitle = oldItem.title;
[oldItem setTitle: #"Back"];
in viewWillDisappear, add the following:
[oldItem setTitle: oldTitle];
oldTitle = nil; // do this if you have retained oldTitle
oldItem = nil; // do this if you have retained oldItem
It's not perfect. You will see the the title of the parent view change as the new controller is animated in. BUT this does achieve the goal of custom labeling the back button and keeping it shaped like a standard back button.
Put this into you viewDidLoad, hope it will result into what you are looking for
UIBarButtonItem *backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:#"Close"
style:UIBarButtonItemStylePlain target:nil action:nil];
self.navigationItem.backBarButtonItem = backBarButtonItem;
[backBarButtonItem release];
if You want to set title in ARRIVING controller (sometimes more logic..)
in swift 3 do:
func setBackButtonNavBar(title: String, delay: Double){
let when = DispatchTime.now() + delay
DispatchQueue.main.asyncAfter(deadline: when, execute: { () -> Void in
if let navBar = self.navigationController?.navigationBar{
navBar.backItem?.title = title
}
})
}
in upcoming controller:
override func viewDidLoad() {
super.viewDidLoad()
self.setBackButtonNavBar(title: "back", delay: 0.3)
}
usually I put self.setBackButtonNavBar in a controller extension.
I know this is an old question and the answers' kind of out updated!
The easy way is to do this in parent ViewController:
i.e the one that takes you to next view controller.
self.navigationItem.backBarButtonItem = UIBarButtonItem(title: "Custom text here", style: .plain, target: nil, action: nil)
Doing this in code remove the back button style of the UINavigationConroller. If you add a Navigation Item in each of yours views, you can set the title of the back botton in the StoryBoard.

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