How to disable multitouch?

问题:

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?

回答1:

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

回答2:

- (void)viewDidLoad {
    [super viewDidLoad];

    for(UIView* v in self.view.subviews)
    {
        if([v isKindOfClass:[UIButton class]])
        {
            UIButton* btn = (UIButton*)v;
            [btn setExclusiveTouch:YES];
        }
    }
}

回答3:

- (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.

回答4:

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.

回答5:

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.

回答6:

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;
}

回答7:

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

回答8:

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.

回答9:

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.

回答10:

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.

回答11:

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];
}

回答12:

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  
}

回答13:

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;
    }
    ------
    ------
}

回答14:

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
    }
}

回答15:

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
}

回答16:

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

回答17:

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
    ...
}

回答18:

Just set all relevant UIView's property exclusiveTouch to false do the trick.