func showFilterPanel() {
println("Showing")
}
let backButton = UIBarButtonItem(title: "Horse", style: UIBarButtonItemStyle.Plain, target: nil, action: "showFilterPanel")
#IBAction func tapGesture(sender: AnyObject) {
self.navigationItem.leftBarButtonItem = self.backButton
}
The above code is embedded in a Map Navigation Controller. The action has no effect, any ideas why (I don't see "Showing" in the console)?
You passed nil as the target for the selector. It should be self in this case:
let backButton = UIBarButtonItem(title: "Horse", style: UIBarButtonItemStyle.Plain, target: nil, action: "showFilterPanel")
You'll also need to rearrange this to move the instantiation of the UIBarButtonItem down to method scope in order to be able to reference self in its instantiation. When you create a property in Swift you can't reference other properties or self in its creation, unless it's a computed or lazily instantiated property.
Related
I have UIBarButtonItem and the selector method is not being called, been driving me nuts for days.
These are in my viewDidLoad method
let doneButton = UIBarButtonItem(title: "Done", style: .plain, target: nil, action: #selector(self.doneButtonPressed))
self.navigationItem.rightBarButtonItem = doneButton
let cancelButton = UIBarButtonItem(title: "Cancel", style: .plain, target: nil, action: #selector(self.cancelButtonPressed))
self.navigationItem.leftBarButtonItem = cancelButton
and here are the methods:
#objc func doneButtonPressed()
{
dismiss(animated: true, completion: nil)
}
#objc func cancelButtonPressed()
{
dismiss(animated: true, completion: nil)
}
How come they are not being called?
You should set target to self instead of nil
let doneButton = UIBarButtonItem(title: "Done", style: .plain, target: self, action: #selector(self.doneButtonPressed))
You need to set a valid target in UIBarButtonItem(title:style:target:action:).
This is how it works behind the scenes: #selector transforms your selector into a Selector type: something that is almost – but not quite – a string. The Objective C runtime later uses that Selector to send a message with the Selector as its content to target; i.e. it calls the selector on the target.
Therefore, you must add the #objc annotation to your target and you must add the target to the constructor.
I have added a navigation bar to the top of a view controller. I am trying to control whether a button is visible based a condition, but I am having trouble adding the button. So far I have,
var addButton: UIBarButtonItem = UIBarButtonItem(title: "test", style: .done, target: self, action: #selector(addTapped))
override func viewDidLoad() {
super.viewDidLoad()
let boool = true
if boool {
self.navigationItem.rightBarButtonItem = self.addButton
}
else {
self.navigationItem.rightBarButtonItem = nil
}
}
func addTapped(sender: AnyObject) {
print("hjxdbsdhjbv")
}
I believe it is not working properly because I have added a navigation bar into the VC, instead of using a navigation controller and working with the bar there. I was wondering if there was a way to work with this navigation bar.
It’s simple. Put this line of code to the viewDidLoad:
self.navigationItem.rightBarButtonItem = UIBarButtonItem(title: "test", style: .done, target: self, action: #selector(addTapped))
Updated for Swift 4 or later:
A custom function:
#objc func action(sender: UIBarButtonItem) {
// Function body goes here
}
(Custom) Right bar button item:
self.navigationItem.rightBarButtonItem = UIBarButtonItem.init(title: "some_text", style: .done, target: self, action: #selector(self.action(sender:)))
(Custom) Left bar button item:
self.navigationItem.leftBarButtonItem = UIBarButtonItem.init(title: "some_text", style: .done, target: self, action: #selector(self.action(sender:)))
Also you can add a system bar button items something like this: UIBarButtonItem.SystemItem Defines system-supplied images for bar button items: .add, .done, .cancel, .edit, .save, .compose, .reply, .organize and more.
(System) Right bar button item:
self.navigationItem.rightBarButtonItem = UIBarButtonItem.init(barButtonSystemItem: UIBarButtonItem.SystemItem.add, target: self, action: #selector(self.action(sender:)))
(System) Left bar button item:
self.navigationItem.leftBarButtonItem = UIBarButtonItem.init(barButtonSystemItem: UIBarButtonItem.SystemItem.add, target: self, action: #selector(self.action(sender:)))
let rightBarButtonItem = UIBarButtonItem.init(image: UIImage(named: "EditImage"), style: .done, target: self, action: #selector(ViewController.call_Method))
self.navigationItem.rightBarButtonItem = rightBarButtonItem
You say you added a UINavigationBar to your view controller via storyboard, but looking at the code you provided there is no outlet connection to your navigation bar in IB.
In order to access self.navigationItem your view controller must be embedded in a UINavigationController or be part of a hierarchy which is. Unless you have a need for a custom navigation bar on an individual view controller, I suggest removing that from Interface Builder, then making sure either the view controller in question is embedded in a UINavigationController or it is being pushed onto the navigation stack from another controller which is embedded in a navigation controller and then you should see your UIBarButtonItem.
Firstly, you need to connect you navigation bar to an IBOutlet so that you can refer to it in your code. After that, this code should work:
let navigationItem = UINavigationItem(title: "Title")
navigationItem.rightBarButtonItem = self.addButton
navigationItem.hidesBackButton = true
self.navigationBar.pushItem(navigationItem, animated: false)
Swift 4.2;
Add viewController
override func viewDidLoad() {
super.viewDidLoad()
self.addNavigationBarButton(imageName: "ic_back", direction:.left)
}
Add Class your API or Utility Class
public func addNavigationBarButton(imageName:String,direction:direction){
var image = UIImage(named: imageName)
image = image?.withRenderingMode(.alwaysOriginal)
switch direction {
case .left:
self.navigationItem.leftBarButtonItem = UIBarButtonItem(image: image, style:.plain, target: nil, action: #selector(goBack))
case .right:
self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: image, style:.plain, target: nil, action: #selector(goBack))
}
}
#objc public func goBack() {
self.navigationController?.popViewController(animated: true)
}
public enum direction {
case right
case left
}
tested in Xcode 10.2, swift 5.0;
First, I have have embedded my ViewController in UINavigationController in IB.
Then in ViewDidLoad include these lines
self.title = "orange"
self.navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(changeLayout)).
Note - accessing title, or adding button through navigation controller did not work. For example : setting title - Self.navigationcontroller.navigationItem.title did not work ,
I have a Navigation controller and I'm trying to put a button on the right of navigation bar but I can't handle the tap action. I'm declaring the UIBarButtonItem like this
let navigationButton = UIBarButtonItem.init(title: "Logout", style: .done, target: self, action: #selector(RestaurantsListViewController.logoutAction))
I'm adding the button on the viewDidLoad func
override func viewDidLoad() {
super.viewDidLoad()
self.navigationItem.rightBarButtonItem = navigationButton
}
and the function that I'm trying to use to handle the tap event is this
func logoutAction(sender: AnyObject?){
print("Logout")
}
but when I press the button, the message is not printed in console.
Try this:
override func viewDidLoad() {
super.viewDidLoad()
self.navigationItem.rightBarButtonItem = UIBarButtonItem(title: "ButtonName", style: .done, target: self, action: #selector(YourViewController.yourAction))
}
let okbtn = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.plain, target: self, action: #selector(ViewController.logoutAction))
Try This
otherwise You need to replace func like
func logoutAction()
{
print("logout")
}
The issue here is when you create navigationButton as a class property, it gets initialized before self is initialized. So self doesn't exist yet when you pass it in as the target of the button.
There are a couple ways to fix it, including the answer by #Mannopson where you initialize the button inside the viewDidLoad, which ensures that self has already been created.
Another way to solve this issue is to declare navigationButton to be a lazy var:
lazy var navigationButton = UIBarButtonItem.init(title: "Logout", style: .done, target: self, action: #selector(RestaurantsListViewController.logoutAction))
The lazy var ensures that the property only gets initialized when the property gets accessed (hence it being a lazy initialization). Since the first time it is accessed happens in viewDidLoad, we can also be sure that self has been created. Hope this gives you more context!
I have a following helper class
class PDFPreviewHelper {
var pdfNavigationController: UINavigationController!
func previewButtonPressed(rootViewController: UIViewController) {
let pdfViewController = PDFViewController(resource: "final.pdf")
pdfNavigationController = UINavigationController(rootViewController: pdfViewController)
let backButton = UIBarButtonItem(title: "Back", style: UIBarButtonItemStyle.Plain, target: self, action: "backButtonPressedInPDF")
pdfViewController.navigationItem.setLeftBarButtonItem(backButton, animated: false)
rootViewController.presentViewController(pdfNavigationController, animated: true, completion: nil)
}
func backButtonPressedInPDF() {
pdfNavigationController.dismissViewControllerAnimated(true, completion: nil)
}
}
I call a function in above helper class in my rootviewcontroller like following:
func previewInPdfButtonPressed() {
let a = PDFPreviewHelper()
a.viewI129InPDF(self)
}
I successfully modally present pdfNavigationController on top of my rootViewController, but whenever i press back button, nothing gets called. Why is this so? I set a break point in backButtonPressedInPDF function and it doesn't even hit the break point.
You need to assign leftBarButtonItem to UINavigationController via below way.
pdfViewController.navigationItem.leftBarButtonItem = UIBarButtonItem(title: "Back", style: UIBarButtonItemStyle.Plain, target: self, action: "backButtonPressedInPDF")
I think the problem lies here.
let backButton = UIBarButtonItem(title: "Back", style: UIBarButtonItemStyle.Plain, target: self, action: "backButtonPressedInPDF")
To:
let backButton = UIBarButtonItem(title: "Back", style: UIBarButtonItemStyle.Plain, target: self, action: "backButtonPressedInPDF:")
I believe the problem as at action: "backButtonPressedInPDF" where there is a missing :
In addition, change your method by adding (sender:AnyObject) also?
func backButtonPressedInPDF(sender:AnyObject) {
pdfNavigationController.dismissViewControllerAnimated(true, completion: nil)
}
The issue is you are creating a temporary instance of PDFPreviewHelper class and using it to present the view controller. Not keeping the reference.
This can be fixed in two ways:
Method 1: Add previewInPdfButtonPressed method to your PDFViewController class. Then change implementation like following.
let backButton = UIBarButtonItem(title: "Back", style: UIBarButtonItemStyle.Plain, target: pdfViewController, action: "backButtonPressedInPDF")
Method 2:
You should keep the object a until you dismiss your PDFViewController-navigationcontroller.
Even if you do like this you will get an exception like
2016-03-16 15:43:03.140 XXXX[3757:585277] *** NSForwarding: warning: object 0x7ff5eb72be70 of class 'XXXX.PDFPreviewHelper' does not implement methodSignatureForSelector: -- trouble ahead
Unrecognized selector -[XXXX.PDFPreviewHelper backButtonPressedInPDF]
This is because you are not subclassing NSObject for your PDFPreviewHelper.
You can fix it in two ways,
Make PDFPreviewHelper as NSObject subclass.
Add dynamic
keyword to the function like dynamic func previewInPdfButtonPressed() {....}.
Resolution to this issue is well described here
func previewInPdfButtonPressed()
{
let a = PDFPreviewHelper()
a.viewI129InPDF(self)
}
The problem is a is released when the program goes out of the scope of this function. The action you target on a of course can't be executed anymore
solution add a as a property of the viewController
I'm trying to set in almost each page a custom back button and I'm repeating the same code in each page like this;
let buttonItem = UIBarButtonItem(image: UIImage(named: "arrow_back"), style: UIBarButtonItemStyle.Plain, target: self, action:"popBack")
buttonItem.tintColor=UIColor.blackColor()
navigationItem.leftBarButtonItem = backButtonItem()
And I think this is the wrong way for it. So please could you tell what is the best way for this?
I've done this by creating a category on UIViewController. In that file I created a method called addBackButton, where you can put your code in once, then expose the method in your .h file. Then in any of your view controller subclasses you can import your category and call [self addBackButton];
You have various options here.
1) UIViewController extension
extension UIViewController {
func brandedBackButton() {
let buttonItem = UIBarButtonItem(image: UIImage(named: "back"), style: UIBarButtonItemStyle.Plain, target: self, action:"popBack")
buttonItem.tintColor=UIColor.blackColor()
navigationItem.leftBarButtonItem = buttonItem
}
}
and then just call in your view controller
override func viewDidLoad() {
super.viewDidLoad()
brandedBackButton()
}
2) Base View Controller Class
You would basically put a class in between your controllers and the UIViewController.
class BaseViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let buttonItem = UIBarButtonItem(image: UIImage(named: "back"), style: UIBarButtonItemStyle.Plain, target: self, action:"popBack")
buttonItem.tintColor=UIColor.blackColor()
navigationItem.leftBarButtonItem = buttonItem
}
}
and then you would inherit from this BaseViewController instead of standard UIViewController.
class YourWhateverViewController: BaseViewController {
//implementation here....
}
Both the category and the base class can also accommodate the popBack custom method so you would end up really with literally 10 characters to get this behaviour anywhere...
I suggest you create a custom UIButton class and reuse it every time you want it.
class backButtonItem: UIBarButtonItem {
convenience init(target: AnyObject?) {
self.init(image: UIImage(named: "arrow_back"), style: .Plain, target: target, action: "popBack")
self.tintColor = UIColor.blackColor()
}}
just type the following script when you use it:
navigationItem.leftBarButtonItem = backButtonItem(target: self)