I am trying to create a "Power Button" for my calculator app that will turn the calculator on/off. I created the button:
-(IBAction) *Power;
Without the power button, the app starts with "0" in the LCD display, and my buttons are all working; but how can I tell my app that the LCD should display "" and the buttons cannot be manipulated until the power button is pressed? Would a simple if-then function work? Can I put -(IBAction) buttons within if-thens?
Create a BOOL property, that and check for YES in all the IBACtions.
You need to set it to YES/NO on the method Power, typically as:
Initiaze it with NO in your init or viewDidLoad, whichever is applicable.
-(IBAction) power{
self.powerOn=!self.powerOn;
}
-(IBAction) otherMethod{
if(self.powerOn){
//do your stuff
}
}
Also, method with pointer -(IBAction) *Power; is not that you need here.
1) declare a variable to track power on/off
#property(nonatomic, assign) BOOL powerOn;
in viewDidLoad,
assign _powerOn = NO; or _powerOn = YES;
2) inside your power button pressed event,
-(IBAction) Power;{
//if on, then off
if(self.powerOn){
//make display ""
self.powerOn = NO;
}else{ //if off, the on
self.powerOn = YES;
//make display "0"
}
}
3) add following line as the 1st line in all other button click events
-(IBAction) otherMethod{
if(!self.powerOn) return;
//your code
}
You Need to create IBOutlets for your Buttons, to edit behaviors of them while running the app.
These IBOutlets are created like this:
IBOutlet UIButton *myPowerButton;
You need to link them with the button in Interface Builder where you created the Outlet for.
There you can specify the 'Enabled' behavior to be YES or NO, so you can make a Power Button to set if the user can work or not.
For further information please read Apples Documentation about IBOutlets and Buttons.
UIButton Apple Documentation
I would do this way, assuming the title of the button is Power:
-(IBAction) Power
{
if(self.powerOn)
{
//make display ""
self.powerOn = NO;
for (UIView* subView in self.view.subviews)
{
if ([subView isMemberOfClass:[UIButton class]] && subView.titleLabel.text != #"Power")
subView.userInteractionEnabled = NO;
}
}
else
{ //if off, the on
self.powerOn = YES;
//make display "0"
}
}
I would disable the User interaction of all other button when powerbutton is off.
I have the need for an UIButton to maintain a pressed state. Basically, if a button is in a normal state, I want to touch the button, it highlight to its standard blue color and then stay blue after lifting my finger.
I made the following UIAction and connected the buttons Touch Up Inside event to it.
-(IBAction) emergencyButtonPress:(id) sender
{
if(emergencyButton.highlighted)
{
emergencyButton.selected = NO;
emergencyButton.highlighted = NO;
}
else
{
emergencyButton.selected = YES;
emergencyButton.highlighted = YES;
}
}
But what happens, after I remove my finger, the button goes back to a white background. For a test I added a UISwitch and have it execute the same code:
-(IBAction) emergencySwitchClick:(id) sender
{
if(emergencyButton.highlighted)
{
emergencyButton.selected = NO;
emergencyButton.highlighted = NO;
}
else
{
emergencyButton.selected = YES;
emergencyButton.highlighted = YES;
}
}
In this case the button toggles to a highlighted and non-highlighted state as I would expect.
Is there another event happening after the Touch Up Inside event that is resetting the state back to 'normal'? How do I maintain the highlighted state?
The highlighted state is applied and removed by iOS when you touch / release the button. So don't depend on it in your action method.
As one of the other answers says, set the highlighted image to be the same as the selected image, and then modify your action method:
-(IBAction) emergencyButtonPress:(id) sender
{
emergencyButton.selected = !emergencyButton.selected;
}
If you want something like a toggle button, customize your "selected" state to be your "pressed" state, and then write something like this:
- (IBAction)buttonTapped:(id)sender {
[(UIButton*)sender setSelected:![sender isSelected]];
}
if you want the above code to work, you should set an image for the state selected and one (even the same) for he state highlighted.
[emergencyButton setBackgroundImage:buttonHighlightImage forState:UIControlStateHighlighted];
[emergencyButton setBackgroundImage:buttonHighlightImage forState:UIControlStateSelected];
hope it helps.
I had this same problem, and this is what worked for me:
-(IBAction)buttonPressed:(id)sender {
if (isSelected) {
[_button setSelected:NO];
[_button setImage:[UIImage imageNamed:#"not_selected.png"] forState:UIControlStateSelected];
isSelected=NO;
}
else {
[_button setSelected:YES];
[_button setImage:[UIImage imageNamed:#"selected.png"] forState:UIControlStateSelected];
isSelected=YES;
}
}
This is not possible unfortunately, as soon as you let go Apple changes the state again.
One option I've used before (but not pretty) is that you use a performSelector with delay 0.1 after the button is pressed to put it again in the selected state. This did work in my case.
EDIT: If you don't want to see the blinking effect, just set the delay to 0.0
This worked for me:
- (void)tapButton:(id)sender{
UIButton *button = sender;
if (!button.selected){
[self performSelector:#selector(highlight:) withObject:button afterDelay:0.0];
}else{
[self performSelector:#selector(removeHighlight:) withObject:button afterDelay:0.0];
}
}
- (void)highlight:(UIButton *)button{
button.selected = !button.selected;
button.highlighted = YES;
}
- (void)removeHighlight:(UIButton *)button{
button.selected = !button.selected;
button.highlighted = NO;
}
Try this simple answer....
- (void)mybutton:(id)sender
{
UIButton *button = (UIButton *)sender;
button.selected = ![button isSelected]; // Important line
if (button.selected)
{
NSLog(#"Selected");
NSLog(#"%i",button.tag);
}
else
{
NSLog(#"Un Selected");
NSLog(#"%i",button.tag);
}
}
i am trying to implement my own gesture recognizer in addition to the one already used by the MKMapView. Right now i can tap on the map and set a pin. This behavior is realized by my UITapGestureRecognizer. When i tap on a pin that already exists, my gesture recognizer does nothing, but instead the callout bubble of this pin is shown. The UIGestureRecognizerDelegate looks like this:
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
if (gestureRecognizer == self.tapRecognizer)
{
bool hitAnnotation = false;
int count = [self.mapView.annotations count];
int counter = 0;
while (counter < count && hitAnnotation == false )
{
if (touch.view == [self.mapView viewForAnnotation:[self.mapView.annotations objectAtIndex:counter]])
{
hitAnnotation = true;
}
counter++;
}
if (hitAnnotation)
{
return NO;
}
}
return YES;
}
This works fine. My only problem are the callout bubbles of the pins and the double tap. Normally the double tap is used for zooming in. This still works but in addition to this, i also get a new pin. Is there any way to avoid this?
The other problem occurs with the callout bubble of a pin. I can open the bubble by tapping on the pin without setting a new pin at this place (see code above) but when i want to close the bubble by tapping on it, another pin is set. My problem is, that i cannot check with touch.view , if the user tapped on a callout bubble, because it is not a regular UIView as far as i know. Any ideas or workarounds for this problem?
Thanks
I had the same problem as your first problem: distinguishing double taps from single taps in an MKMapView. What I did was the following:
[doubleTapper release];
doubleTapper = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(mapDoubleTapped:)];
doubleTapper.numberOfTapsRequired = 2;
doubleTapper.delaysTouchesBegan = NO;
doubleTapper.delaysTouchesEnded = NO;
doubleTapper.cancelsTouchesInView = NO;
doubleTapper.delegate = self;
[mapTapper release];
mapTapper = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(mapTapped:)];
mapTapper.numberOfTapsRequired = 1;
mapTapper.delaysTouchesBegan = NO;
mapTapper.delaysTouchesEnded = NO;
mapTapper.cancelsTouchesInView = NO;
[mapTapper requireGestureRecognizerToFail:doubleTapper];
and then implemented the following delegate method:
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}
Using requireGestureRecognizerToFail: allows the app to distinguish single taps from double taps and implementing gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer: ensures that double taps are still forwarded to the MKMapView so that it continues zooming normally. Note that doubleTapper doesn't actually do anything (in my case, except log debug messages). It's simply a dummy UIGestureRecognizer that's used to help separate single taps from double taps.
Okay. In Xcode, I want my application to run a line of code once the UISlider gets to 1.00 or the end of the slider. How would I do this?
Add these to your UIViewController.
In your .h, below the interface:
-(IBAction)sliderChangedValue:(id) sender;
In your .m:
-(IBAction)sliderChangedValue:(id) sender {
if([sender isKindOfClass:[UISlider class]]) {
UISlider *slider = (UISlider *)sender;
if(slider.value == 0.0 || slider.value == 1.0) {
//your line of code
}
}
}
Then in Interface Builder connect Value Changed of your UISlider to this method.
Write an IBAction method, and connect it to your UISlider in Interface Builder, selecting "On Changed Value" in the dialog that will appear. Then add some code like this to the method:
if(mySlider.value == 1.0f){
//Insert your code here
}
--James
My app has several buttons which trigger different events. The user should NOT be able to hold down several buttons. Anyhow, holding down several buttons crashes the app.
And so, I'm trying to disable multi-touch in my app.
I've unchecked 'Multiple Touch' in all the xib files, and as far as I can work out, the properties 'multipleTouchEnabled' and 'exclusiveTouch' control whether the view uses multitouch. So in my applicationDidFinishLaunching I've put this:
self.mainViewController.view.multipleTouchEnabled = NO;
self.mainViewController.view.exclusiveTouch = YES;
And in each of my view controllers I've put this in the viewDidLoad
self.view.multipleTouchEnabled = NO;
self.view.exclusiveTouch = YES;
However, it still accepts multiple touches. I could do something like disable other buttons after getting a touch down event, but this would be an ugly hack. Surely there is a way to properly disable multi-touch?
If you want only one button to respond to touches at a time, you need to set exclusiveTouch for that button, rather than for the parent view. Alternatively, you could disable the other buttons when a button gets the "Touch Down" event.
Here's an example of the latter, which worked better in my testing. Setting exclusiveTouch for the buttons kind-of worked, but led to some interesting problems when you moved your finger off the edge of a button, rather than just clicking it.
You need to have outlets in your controller hooked up to each button, and have the "Touch Down", "Touch Up Inside", and "Touch Up Outside" events hooked to the proper methods in your controller.
#import "multibuttonsViewController.h"
#implementation multibuttonsViewController
// hook this up to "Touch Down" for each button
- (IBAction) pressed: (id) sender
{
if (sender == one)
{
two.enabled = false;
three.enabled = false;
[label setText: #"One"]; // or whatever you want to do
}
else if (sender == two)
{
one.enabled = false;
three.enabled = false;
[label setText: #"Two"]; // or whatever you want to do
}
else
{
one.enabled = false;
two.enabled = false;
[label setText: #"Three"]; // or whatever you want to do
}
}
// hook this up to "Touch Up Inside" and "Touch Up Outside"
- (IBAction) released: (id) sender
{
one.enabled = true;
two.enabled = true;
three.enabled = true;
}
#end
- (void)viewDidLoad {
[super viewDidLoad];
for(UIView* v in self.view.subviews)
{
if([v isKindOfClass:[UIButton class]])
{
UIButton* btn = (UIButton*)v;
[btn setExclusiveTouch:YES];
}
}
}
- (void)viewDidLoad {
[super viewDidLoad];
for(UIView* v in self.view.subviews)
{
if([v isKindOfClass:[UIButton class]])
{
UIButton* btn = (UIButton*)v;
[btn setExclusiveTouch:YES];
}
}
}
This code is tested and working perfectly for me.there is no app crash when pressing more than one button at a time.
Your app crashes for a reason. Investigate further, use the debugger, see what's wrong instead of trying to hide the bug.
Edit:
OK, ok, I have to admit I was a bit harsh. You have to set the exclusiveTouch property on each button. That's all. The multipleTouchEnabled property is irrelevant.
To disable multitouch in SWIFT:
You need first to have an outlet of every button and afterwards just set the exclusive touch to true.Therefore in you viewDidLoad() would have:
yourButton.exclusiveTouch = true.
// not really necessary but you could also add:
self.view.multipleTouchEnabled = false
If you want to disable multi touch throughout the application and don't want to write code for each button then you can simply use Appearance of button. Write below line in didFinishLaunchingWithOptions.
UIButton.appearance().isExclusiveTouch = true
Thats great!! UIAppearance
You can even use it for any of UIView class so if you want to disable multi touch for few buttons. Make a CustomClass of button and then
CustomButton.appearance().isExclusiveTouch = true
There is one more advantage which can help you. In case you want to disable multi touch of buttons in a particular ViewController
UIButton.appearance(whenContainedInInstancesOf: [ViewController2.self]).isExclusiveTouch = true
Based on neoevoke's answer, only improving it a bit so that it also checks subviews' children, I created this function and added it to my utils file:
// Set exclusive touch to all children
+ (void)setExclusiveTouchToChildrenOf:(NSArray *)subviews
{
for (UIView *v in subviews) {
[self setExclusiveTouchToChildrenOf:v.subviews];
if ([v isKindOfClass:[UIButton class]]) {
UIButton *btn = (UIButton *)v;
[btn setExclusiveTouch:YES];
}
}
}
Then, a simple call to:
[Utils setExclusiveTouchToChildrenOf:self.view.subviews];
... will do the trick.
This is quite often issue being reported by our testers. One of the approach that I'm using sometimes, although it should be used consciously, is to create category for UIView, like this one:
#implementation UIView (ExclusiveTouch)
- (BOOL)isExclusiveTouch
{
return YES;
}
Pretty much simple you can use make use of ExclusiveTouch property in this case
[youBtn setExclusiveTouch:YES];
This is a Boolean value that indicates whether the receiver handles touch events exclusively.
Setting this property to YES causes the receiver to block the delivery of touch events to other views in the same window. The default value of this property is NO.
For disabling global multitouch in Xamarin.iOS
Copy&Paste the code below:
[DllImport(ObjCRuntime.Constants.ObjectiveCLibrary, EntryPoint = "objc_msgSend")]
internal extern static IntPtr IntPtr_objc_msgSend(IntPtr receiver, IntPtr selector, bool isExclusiveTouch);
static void SetExclusiveTouch(bool isExclusiveTouch)
{
var selector = new ObjCRuntime.Selector("setExclusiveTouch:");
IntPtr_objc_msgSend(UIView.Appearance.Handle, selector.Handle, isExclusiveTouch);
}
And set it on AppDelegate:
public override bool FinishedLaunching(UIApplication app, NSDictionary options)
{
...
SetExclusiveTouch(true); // setting exlusive to true disables the multitouch
...
}
My experience is that, by default, a new project doesn't even allow multitouch, you have to turn it on. But I suppose that depends on how you got started. Did you use a mutlitouch example as a template?
First of all, are you absolutely sure multitouch is on? It's possible to generate single touches in sequence pretty quickly. Multitouch is more about what you do with two or more fingers once they are on the surface. Perhaps you have single touch on but aren't correctly dealing with what happens if two buttons are pressed at nearly the same time.
I've just had exactly this problem.
The solution we came up with was simply to inherit a new class from UIButton that overrides the initWithCoder method, and use that where we needed one button push at a time (ie. everywhere):
#implementation ExclusiveButton
(id)initWithCoder: (NSCoder*)decoder
{
[self setExclusiveTouch:YES];
return [super initWithCoder:decoder]
}
#end
Note that this only works with buttons loaded from nib files.
I created UIView Class Extension and added this two functions. and when i want to disable view touch i just call [view makeExclusiveTouch];
- (void) makeExclusiveTouchForViews:(NSArray*)views {
for (UIView * view in views) {
[view makeExclusiveTouch];
}
}
- (void) makeExclusiveTouch {
self.multipleTouchEnabled = NO;
self.exclusiveTouch = YES;
[self makeExclusiveTouchForViews:self.subviews];
}
If you want to disable multitouch programmatically, or if you are using cocos2d (no multipleTouchEnabled option), you can use the following code on your ccTouches delegate:
- (BOOL)ccTouchesBegan:(NSSet *)touches
withEvent:(UIEvent *)event {
NSSet *multiTouch = [event allTouches];
if( [multiTouch count] > 1) {
return;
}
else {
//else your rest of the code
}
Disable all the buttons on view in "Touch Down" event and enable them in "Touch Up Inside" event.
for example
- (void) handleTouchDown {
for (UIButton *btn in views) {
btn.enable = NO;
}
}
- (void) handleTouchUpInside {
for (UIButton *btn in views) {
btn.enable = Yes;
}
------
------
}
I decided this problem by this way:
NSTimeInterval intervalButtonPressed;
- (IBAction)buttonPicturePressed:(id)sender{
if (([[NSDate date] timeIntervalSince1970] - intervalButtonPressed) > 0.1f) {
intervalButtonPressed = [[NSDate date] timeIntervalSince1970];
//your code for button
}
}
I had struggled with some odd cases when dragging objects around a view, where if you touched another object at the same time it would fire the touchesBegan method. My work-around was to disable user interaction for the parent view until touchesEnded or touchesCancelled is called.
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
// whatever setup you need
self.view.userInteractionEnabled = false
}
override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
// whatever setup you need
self.view.userInteractionEnabled = true
}
override func touchesCancelled(touches: Set<UITouch>?, withEvent event: UIEvent?) {
// whatever setup you need
self.view.userInteractionEnabled = true
}
A Gotcha:
If you are using isExclusiveTouch, be aware that overriding point(inside:) on the button can interfere, effectively making isExclusiveTouch useless.
(Sometimes you need to override point(inside:) for handling the "button not responsive at bottom of iPhone screen" bug/misfeature (which is caused by Apple installing swipe GestureRecognizers at the bottom of the screen, interfering with button highlighting.)
See: UIButton fails to properly register touch in bottom region of iPhone screen
Just set all relevant UIView's property exclusiveTouch to false do the trick.