I wanted to use a custom UIMenuController in WKWebView.
First, I wanted to get rid of the default menu (Copy, Look up, Share), but for some reason I don't know, but it hasn't disappeared.
override open func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
switch action {
case #selector(highlightHandler):
return true
default:
return false
}
}
func enableCustomMenu() {
let memo = UIMenuItem(title: "메모", action: #selector(highlightHandler))
UIMenuController.shared.menuItems = [memo]
UIMenuController.shared.update()
}
#objc func highlightHandler(sender: UIMenuItem) { }
I tried using the code above to remove the default menuItems and add custom menuItems called "메모", but it didn't.
How can I show only the items I want called "메모"?
canPerformAction() cannot reject an option in most cases. It can only tell the system that the class it's being called in is willing to provide the needed function. Returning False just says "I can't do that one", and then the next item in the responder chain is called and eventually something is found that says "Yes, I can do that". Having said that, it seems that I get a different result if I override this function on the item that is the first responder. In that case, False actually seems to disable the command. So if you can implement canPerformAction() on the first-responder, do that. If not...
Basically you have to temporarily break the responder chain. You do that by overriding the UIResponder "next" variable so that it conditionally returns nil when you want the chain broken. You don't want it to leave it broken for long or bad things will happen. Anything that was approved by the FirstResponder or things in the responder chain between First and you will still be approved, but that will stop approval of things after you in the chain.
Related
I have a custom titleView with 2 custom UIButtons with arrow images that allow navigation to the next view controller in the paging structure. They work perfectly fine until a button is tapped within the WKWebView. Then they don't work anymore and the selector is not called. Note that other buttons in the nav bar still work (UIBarButtonItems). The buttons work properly again after the user swipes over to the next view controller.
After looking into it some, it looks like a WKCompositingView becomes first responder and if I override becomeFirstResponder() in a WKWebView subclass, the issue goes away. I'm still a little baffled though, and would like to understand the root of the problem.
class NonFirstRespondableWebView: WKWebView {
override func becomeFirstResponder() -> Bool {
return false
}
}
Does anyone have any insight into why this is happening?
Most UI elements in swift have a UIResponder. Unhandled events are passed up the responder chain to enclosing views. My guess is that the WKWebView is absorbing all touch events once the window has become active. You can learn more about the responder chain here
Regarding a first responder. From the docs:
The first responder is usually the first object in a responder chain to receive an event or action message. In most cases, the first responder is a view object that the user selects or activates with the mouse or keyboard.
Assuming you want to keep interactivity with the WKWebView fully functional (e.g. you need to bring up a keyboard or something), you can use
webView.resignFirstResponder()
To resign the responder at any time.
Otherwise, an extension that would give you the same functionality might look something like this:
extension WKWebView {
open override func becomeFirstResponder() -> Bool {
if self.superview?.superview is UIWebView {
return false
} else {
return super.becomeFirstResponder()
}
}
}
In my swift iOS application, I have a simple UISwitch control. I have connected the value changed outlet to my #IBAction. The code looks like this:
#IBAction func userDidSelectVisibiltySwitch(_ sender: Any) {
if self.visibilitySwitch.isOn {
if badCondition {
self.visibilitySwith.setOn(false, animated: false)
return
}
} else { // Strangely, it executes the else (I think because the compiler is evaluating the isOn condition again when it arrives to the else {}
// work to be done if the user has turned off the switch
}
}
I suspect that in this case, as I am turning the switch off before the else is evaluated, the compiler executes the else {} statement because it evaluates the above isOn expression again. But how is that possible, given that I placed a 'return' instruction ? that is really beyond me. A confirmation of my suspect comes from the fact that if I dispatch_async using GCD the 'self.visibilitySwith.setOn(false, animated: false)' statement, it works properly without executing the else {} statement, because the evaluation of the else takes place before the control is turned off by my statement. My code now looks like this, and it works:
#IBAction func userDidSelectVisibiltySwitch(_ sender: Any) {
if self.visibilitySwitch.isOn {
if badCondition {
DispatchQueue.main.async {
self.visibilitySwith.setOn(false, animated: false)
}
return
}
} else { // In this case it is normal, it does not execute the else {}
// work to be done if the user has turned off the switch
}
}
I think that I am missing something important of swift in this case. Any help is greatly appreciated. I have already provided a solution, but I want to understand the problem. Thanks a lot
Rather than accessing the UISwitch via your sender argument, you go directly to what I assume is the IBOutlet value. Instead of that approach, you can access the sender as outlined below:
#IBAction func userDidSelectVisibiltySwitch(_ sender: UISwitch) {
if sender.isOn && badCondition {
sender.setOn(false, animated: false)
} else { // In this case it is normal, it does not execute the else {}
// work to be done if the user has turned off the switch
}
}
The reason your fix is working is likely because of a slight delay introduced by the dispatch call which allows for the IBOutlet value to update its value.
I have also gone ahead and combined your if statement, as the sample you provide does not require a nested check.
UPDATED BASED ON RMADDY'S COMMENT
This being the solution struck me a bit of code smell, and upon further investigation, I was able to reproduce the scenarios described by OP. This was accomplished by setting the action in Storyboard as seen here:
With that setting, I saw the following:
Original code posted by OP would fail
Adding the DispatchQueue as demonstrated by OP would correct the switch after a brief delay
My posted solution would correctly work
Assuming that this is what the OP has done, then the first correction would be to change the event to Value Changed. Then, as stated by rmaddy in the comment, this would succeed regardless of whether you use the argument or the IBOutlet. Based on the original question, my interpretation was that there was an issue of the outlet value and the switch's state in the interface being out of sync.
In my class I have 11 UITapGestureRecognizers in an array textViewRecognizer attached to 11 out of 100 UITextFields in an array boxArray. When a Textfield is tapped containing a UIGestureRecognizer it runs tappedTextView where I try to get the index of the first responder.
However, due to some weird ordering in how things are executed, the action function only gives me the first responder of the previous first responder to the one that was just tapped.
Also, I have to double tap to even select the text field I was going for! I need to use the tap function and not the text delegates so this has been a real headache.
I have...
#objc func tappedTextField(_ sender: UITapGestureRecognizer) {
for i in 0...99 {
if (boxArray[i]?.isFirstResponder)! {
if let index = boxArray.index(of: boxArray[i]) {
print(index)
break
}
}
}
}
in my viewDidLoad I have
for i in 0...10 {
textFieldTapRecognizer[i].addTarget(self, action: #selector(self.tappedTextField(_:)))
}
In my class I have
I want to set 11 out of 100 textFields to have this a tap recognizer depending on some conditions (I'm just going to use a regular for loop here)
for i in 0...10 {
boxArray[i]?.addGestureRecognizer(textFieldTapRecognizer[i])
}
Is there anyway I can get it to give me the actual first responder, after the tap was made?
Is there anyway to go around the double tap to select the text field that has a UITapGesture?
Any help is greatly appreciated.
Edited: properly named functions
It sounds like you want to remove the automatic editing behavior on a UITextView. You can grab more control over that with the textViewShouldBeginEditing(_ textView: UITextView) -> Bool UITextViewDelegate method, documented here.
If you return false for that method, this should avoid needing a double tap to get to your gesture recognizer. Depending on your use case, you can then "allow" the tap to go to the text view by returning true for the textView you want to be actually edited.
While I'm not 100% clear on the first responder part of your question, since the textView won't be grabbing first responder if it's not starting it's editing mode, this should address that concern I believe. Good luck!
I would add a Tag to my UITextView and set the UITextViewDelegate to my ViewController.
Then I would add the following Delegate method:
func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
print("Textview tag: ", textView.tag)
return false
}
I just noticed that setting a UISwitch's isOn in its IBAction causes the IBAction to be called again. So the following code:
class ViewController: UIViewController {
var count = 0
#IBOutlet weak var mySwitch: UISwitch!
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
mySwitch.isOn = false
}
#IBAction func buttonTapped(_ sender: UIButton) {
mySwitch.isOn = !mySwitch.isOn
}
#IBAction func switchChanged(_ sender: UISwitch) {
print("\(count) pre: \(mySwitch.isOn)")
mySwitch.isOn = !mySwitch.isOn
print("\(count) post: \(mySwitch.isOn)")
count += 1
}
}
prints the following when the switch is turned on one time:
0 pre: true
0 post: false
1 pre: false
1 post: true
switch is turned off in viewDidLoad
switch is turned on by the user
switch is on now when switchChanged (IBAction) is called
0 pre: true is printed
switch is turned off programmatically in switchChanged
0 post: false is printed
switchChanged is called again by the system
switch is off now in switchChanged, and 1 pre: false is called
switch is turned on programmatically
1 post: true is printed
Why is the IBAction called by the system a second time? How does one get around this, say, for example, when wanting to negate the user's action based upon some internal state? I feel like I am missing something embarrassingly obvious, but I'm pretty sure similar code used to work. Is this an iOS bug? It's being run on an iOS 10.2 iPhone 5s simulator, Xcode Version 8.2.1 (8C1002)
It's interesting to note that when the button tied to buttonTapped is tapped (calling that same method), the switch's IBAction is not called.
Your IBAction is presumably hooked up to valueChanged, which doesn't indicate a particular touch event, just exactly what it says, that the value was changed.
I'd suggest setting a variable called something like var didOverrideSwitchValue = false, set it to true just before setting the new switch value, then when the function is called, check for that variable. If it's set to true, then set it to false and return.
Or, if you wish to negate the new setting only when it's turned on, then you could do if (switch.isOn), and then if so then you can respond to it by turning it off, if required.
I've been battling the same issue and found a workaround...
Check the "selected" property on the sender in your switch handler. I've found that it's true the first time through and false the second time, so you can tell if you're really being called by the user action.
I'm guessing whatever is teeing up the event to fire the second time isn't the switch itself, or maybe this property gets cleared after the first event is handled. Maybe a UIKit guru could chime in.
The UISwitch docs for -setOn:animated: say
Setting the switch to either position does not result in an action message being sent.
Seems clear enough. Feels like an OS bug.
Anyway, this seems to work but it makes me uneasy because I don't fully understand why the problem exists in the first place, nor exactly why this fixes it, and I worry that either could change in a future OS update.
UPDATE
This works fine in my little test app but not in my real app, which has a more complex UI hierarchy with a nav bar, tabs, etc. This just reinforces my uneasiness with this solution.
I have a custom UIView (called GridView) that I initialize and then add to a ViewController (DetailViewController). GridView contains several UIButtons and I would like to know in DetailViewController when those buttons are touched. I'm new to Swift and am wondering what is the best pattern to use to get those events?
If you want to do this with notifications, use 1:
func postNotificationName(_ notificationName: String,
object notificationSender: AnyObject?)
in the method that is triggered by your button. Then, in your DetailViewController, add a listener when it is initialized with 2:
func addObserver(_ notificationObserver: AnyObject,
selector notificationSelector: Selector,
name notificationName: String?,
object notificationSender: AnyObject?)
Both functions can be called from NSNotificationCenter.defaultCenter().
Another method would be to add callbacks which you connect once you initialize the GridView in your DetailViewController. A callback is essentially a closure:
var callback : (() -> Void)?
which you can instantiate when needed, e.g.
// In DetailViewController initialization
gridView = GridView()
gridView.callback = { self.doSomething() }
In GridView you can trigger the callback like this:
func onButton()
{
callback?()
}
The callback will only execute, if unwrapping succeeds. Please ensure, that you have read Automatic Reference Counting, because these constructs may lead to strong reference cycles.
What's the difference? You can connect the callback only once (at least with the method I've showed here), but when it triggers, the receiver immediately executes its code. For notifications, you can have multiple receivers but there is some delay in event delivery.
Lets assume your GridView implementation is like as follows:
class GridView : UIView {
// Initializing buttons
let button1:UIButton = UIButton(...)
let button2:UIButton = UIButton(...)
// ...
// Adding buttons to view
self.addSubview(button1)
self.addSubview(button2)
// ...
}
Now, we will add selector methods which will be called when a button is touched. Lets assume implementation of your view controller is like as follows:
class DetailViewController : UIViewController {
let myView:GridView = GridView(...)
myView.button1.addTarget(self, action: "actionForButton1:", forControlEvents: UIControlEvents.TouchUpInside)
myView.button2.addTarget(self, action: "actionForButton2:", forControlEvents: UIControlEvents.TouchUpInside)
// ...
func actionForButton1(sender: UIButton!) {
// Your actions when button 1 is pressed
}
// ... Selectors for other buttons
}
I have to say that my example approach is not a good example for encapsulation principles of Object-Oriented Programming, but I have written like this because you are new to Swift and this code is easy to understand. If you want to prevent duplicate codes such as writing different selectors for each button and if you want to set properties of your view as private to prevent access from "outside" like I just did in DetailViewController, there are much much better solutions. I hope it just helps you!
I think you better create a class called GridView that is inherited from the UIView. Then, you can connect all you UI element with you class as IBOutlet or whatever using tag something like that. Later on, you can ask the instance of GridView in DetailViewController so that you can connect as IBAction.
Encapsulation is one of the principles of OOP.