I'm learning OBJ.C/Xcode/Cocoa here and have run into a question I can't seem to find an answer for.
I want the text in a UILabel to switch between two states (ON/OFF for example) each time the user clicks the same button.
I can get the label to switch to one state, but can't get it to switch "back" when the user clicks the button again. I am assuming there is some logic required, or checking the status of the object once the button is clicked...
Does this require me to keep track of a bool or the "state" of the Label (or button)?
Would this require two methods to be associated to the button, or can it happen with just one?
Thanks for any guidance/pointing in the right direction/Code snips!!!!
~Steve
I got an answer, and it works:
- (IBAction)flip:(id)sender
{
_flipButton.selected = !_flipButton.selected;
self.flipLabel.text = (_flipButton.selected) ? #"ON" : #"OFF";
}
- (IBAction)flip:(id)sender {
[yourButton setSelected:!yourButton.selected];
self.flipLabel.text = (yourButton.selected) ? #"ON" : #"OFF";
}
This toggles the selected state of the button then checks its state to determine which string to pass to the text property of your label.
the easiest way (I think) is to store a BOOL with the state of the UILabel and (on each click of the button) negate the BOOL and set the appropriate text of the Label
You could call this: yourLabel.enabled = !yourLabel.enabled on button click to change the enabled-state of your UILabel. Or what kind of state do you mean ?
Related
I have an app with some buttons, when those buttons are pressed the image on them should change. I assume that the TouchUpInside runs when you tap and remove the finger while still holding inside the area of the element, however it only works rarely and I'm not sure why.
The reason I use TouchUpInside instead of TouchDown is because I want the user to be able to cancel the action.
I'm sorry if I've misunderstood anything about those events and if this has already been asked. I couldn't find an answer to my problem searching the web.
//The IBAction is set to trigger on TouchUpInside
#IBAction func action11(sender: UIButton) {
setTile(sender)
}
func setTile(sender: UIButton) {
if turn {
print("O's turn")
sender.setImage(xTile, forState: .Normal)
turn = false
}
}
EDIT: Added the necessary code
There are some properties of UIButtons which you can use to achieve what you want.
You can use Default and selected state of uibutton to set two different images.
In XIB select state "Default" and assign default image to that state again select state to "Selected" and assign image which you want after button section.
and add following line in button selection method.
-(IBAction)buttonTapped:(UIButton *)sender{
sender.selected = !sender.selected;
}
Your understanding is correct, you need to use touchUpInside.
I assume you are trying to create a button that has a toggle function. On one touch you want the button to have the value Say "X" and when touched again the button has a value "O".
Take a look at this code below, this should do the job.
class ViewController: UIViewController {
var isButtonPressed = false{
// Adding a Property Observer, that reacts to changes in button state
didSet{
if isButtonPressed{
// Set the Value to X.
}else{
// Set the Value to O.
}
}
}
#IBAction func changeButtonValue(sender: UIButton) {
// Toggle the button value.
isButtonPressed = !isButtonPressed
}
}
If you don't set turn=true after the first time, this code is executed it will be executed only one.
if turn {
print("O's turn")
sender.setImage(xTile, forState: .Normal)
turn = false
}
Check if the button frame is large enough to get finger touch.
Apple says at least 35x35 pixel.
I have a UIButton on a form, and want to put it in a disabled state when the form is incomplete. However, I still want to be able to detect if a user attempts to press the button even in its disabled state so that the interface can let the user know that certain required fields on the form are not filled-in yet (and perhaps scroll to that field and point it out, etc.).
There doesn't seem to be any straightforward way to do this. I tried simply attaching a UITapGestureRecognizer to the UIButton but it doesn't respond when the button is in a disabled state.
I'd like to avoid subclassing UIButton if possible, unless it's the only way.
Create a fallback button. Put it behind the main button. Set its background and text colors to [UIColor clearColor] to ensure it won't show up. (You can't just set its alpha to 0 because that makes it ignore touches.) In Interface Builder, the fallback button should be above the main button in the list of subviews, like this:
Give it the same frame as the main button. If you're using autolayout, select both the main and fallback buttons and create constraints to keep all four edges equal.
When the main button is disabled, touches will pass through to the fallback button. When the main button is enabled, it will catch all the touches and the fallback button won't receive any.
Connect the fallback button to an action so you can detect when it's tapped.
Based on #rob idea, I sub-class a UIButton, and add a transparent button before someone addSubview on this button.
This custom UIButton will save many time about adjusting the UI components on the storyboard.
Update 2018/08
It works well, and add some enhanced detail to this sub-class. I have used it for 2 years.
class TTButton : UIButton {
// MARK: -
private lazy var fakeButton : UIButton! = self.initFakeButton()
private func initFakeButton() -> UIButton {
let btn = UIButton(frame: self.frame)
btn.backgroundColor = UIColor.clearColor()
btn.addTarget(self, action: #selector(self.handleDisabledTouchEvent), forControlEvents: UIControlEvents.TouchUpInside)
return btn
}
// Respect this property for `fakeButton` and `self` buttons
override var isUserInteractionEnabled: Bool {
didSet {
self.fakeButton.isUserInteractionEnabled = isUserInteractionEnabled
}
}
override func layoutSubviews() {
super.layoutSubviews()
// NOTE: `fakeButton` and `self` has the same `superView`.
self.fakeButton.frame = self.frame
}
override func willMoveToSuperview(newSuperview: UIView?) {
//1. newSuperView add `fakeButton` first.
if (newSuperview != nil) {
newSuperview!.addSubview(self.fakeButton)
} else {
self.fakeButton.removeFromSuperview()
}
//2. Then, newSuperView add `self` second.
super.willMoveToSuperview(newSuperview)
}
#objc private func handleDisabledTouchEvent() {
//NSLog("handle disabled touch event. Enabled: \(self.enabled)")
self.sendActionsForControlEvents(.TouchUpInside)
}
}
You have a great misunderstanding of user experience.
If a button is disabled, it is meant to be non-interactable.
You can not click on a disabled button, that is why it is disabled.
If you want to warn users about something when that button is clicked (e.g. form not filled correctly or completely), you need to make that button enabled. And just warn users when they click on it, instead of proceeding further with app logic.
Or you can keep that button disabled until form criteria are met, but show what is wrong with the form using another way, like putting exclamation marks near text fields, changing text field colors to red, or something like that...
But never try to add gesture recognizers, or hidden fallback buttons to a disabled button.
Check those and let me know if you see a disabled button:
https://airbnb.com/signup_login
https://spotify.com/us/signup/
https://netflix.com/signup/regform
https://reddit.com/register/
https://twitter.com/signup
https://facebook.com/r.php
https://appleid.apple.com/account
https://accounts.google.com/SignUp
https://login.yahoo.com/account/create
https://signup.live.com/signup
All the proceed buttons on these websites are always enabled, and you get feedback about what is wrong when you try to continue.
And here is really good answer: https://ux.stackexchange.com/a/76306
Long story short: disabled UI elements meant to be not-interactable.
Trying to make them interactable while they are disabled is the same to making them enabled in the first place.
So, for your question's case, it is just a styling issue. Just try styling your button, instead of making it disabled/enabled.
I'm creating a game for iOS and need some help.
Simply put, random letters will be shown in a label(changing at regular interval), and the user must press the button when they recognise a pattern. If they press the button they earn points, and if they miss it, they lose points.
For example:
let's say they are looking for a letter repeating over one gap. They see the letters "R K W K". On the second K they would press the button. I need to be able to check if the button was pressed while that second K was displayed. I have searched here on stack overflow, but I can't really find anything specific to my situation. Thanks in advance for your responses. I'm new here, so I tried to be as specific as possible.
You can do something like this:
Make a global variable of type bool lets call it isMatch.
While displaying other letters make isMatch = false;
When you display the second 'K' (as your example) make isMatch = true
In you button click method check:
if(isMatch){
point++;
}
else point--;
Make sure you change isMatch = false on displaying other letters.
Hope this helps.. :)
As I understood you are displaying K (say) in UILabel and you might be getting input in UITextField, what you should do is implement ValueChanged IBAction for UITextField and add all letters (K, M, X, H) etc in an array what you have on screen for now. When the text changes it will come in above IBAction, match the UITextField's text with the elements of an array. If there is a match, you are done!
Hope this helps!
Just check in the selector for the button ... (If you're using Interface builder replace void with IBAction)
- (void) buttonWasPressed:(UIButton *) sender {
if ([[[sender titleLabel] text] isEqualToString:#"K"])
point ++;
else
point --;
}
try like this
- (void)buttonTapped:(UIButton *)yourbutton;
{
yourbutton.selected = ![yourbutton isSelected];
}
then this
[self.yourbutton isSelected];
I'm writing some code in Xcode for an iPhone app and I want to be able to detect if a method has been run (i.e. a button was pressed, causing that method to run) in another method (I want to use an if statement so that if the button was pressed it will do this, but if it wasn't then it will do something else).
There is no has_method_been_run() function but you can check to see if the state was changed.
For example say method button_clicked() calls method change_font_to_blue(). In this case you can check to see if the font is blue and there for the method was called.
That's a very basic example of course but you could check any number of variables / the state of the UI to see if it was changed.
OR you can add a boolean to an object and just set it to true when you execute you're method that you're watching.
If your example is simply a button press I would change the UIButton's selected state
- (IBAction)buttonSelected:(UIButton *)sender {
sender.selected = YES;
// OR:
// self.myButton.selected = YES;
}
- (void)otherMethod {
if (self.myButton.isSelected) {
// button has been run through the selector method
// if you want, reset button's selected state
self.myButton.selected = NO;
} else {
// button has NOT been run through the selector method
}
}
This is a simple idea and by default the selected state of a UIButton is not visually different. If you want it to be visually changed then you can simply go into IB and change the visuals there for the selected state (including the title):
Then when the button is set to selected (self.myButton.selected = YES;) it will automatically change what the button looks like!
I have a simple question about event handling in iOS applications... suppose you have an app with some buttons that react to the TouchUpInside event calling the same action, what is the best way within the action method to understand what is the button that triggered the event? I know that it can be easily done using the title of the button, but I think it is not the best way if you have a localized app in which button text may change (unless it is possible to reverse the localization of the title, i.e. retrieve the original string from a localized string)... is there a good practice about this topic? Should I use some other property of buttons to distinguish among different buttons?
Thank you in advance for any help.
There is something called a "Tag" that you can set for UIButtons, or anything that can respond to an event for that matter. If you are using Interface Builder, click the attributes inspector for the item and select a value for the tag (integer). In your code do something like this...
...
- (IBAction)buttonReceived:(id)sender
{
if ([sender tag] == 1) {
//Do something
}
else if ([sender tag] == 2) {
//Do something else
}
}
In addition to the tag property, or just in case you are already using the tag for some other purpose that would mean duplicate tag values for one or more different buttons, you can always set up an IBOutlet ivar to each button you needed to check, and then in the IBAction, do something like this:
- (IBAction)buttonReceived:(UIButton *)sender
{
if (sender == myButtonA) {
// processing for button A
}
else if (sender == myButtonB) {
// processing for button B
}
}
It is a bit more work, but it can come in handy at times.