I want to get the coordinates from the user's finger while dragging. I tried this code, but it says the coordinates are always {0, 0},
What's wrong?
- (IBAction)Drag{
UIPanGestureRecognizer *Recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(dragged)];
[self.view addGestureRecognizer:Recognizer];
}
-(void) dragged{
UITouch *touch ;
CGPoint location = [touch locationInView:touch.view];
NSLog(#"%#", NSStringFromCGPoint (location));
}
I also tried NSLog(#"%.2f %.2f" location.x, location.y); and got the same.
Thanks
It's quite normal, you're using touch without having ever assigned a value to it.
The action for a gesture recognizer takes a parameter, which is the recognizer itself, which in turn has a locationInView: method, so you should use that. Also, you need to check the state of the recognizer. Finally, you probably don't want to add the gesture recognizer when you need it, just add it from the start.
// probably in your viewDidLoad
UIPanGestureRecognizer *Recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self
action:#selector(panGestureRecognizerAction:)];
[self.view addGestureRecognizer:Recognizer];
- (void)panGestureRecognizerAction:(UIPanGestureRecognizer *)recognizer
{
if (recognizer.state == UIGestureRecognizerStateBegan ||
recognizer.state == UIGestureRecognizerStateChanged)
{
CGPoint location = [recognizer.state locationInView:touch.view];
NSLog(#"%#", NSStringFromCGPoint (location));
}
}
Related
I developed an application which allows to the user to draw his finger signature in a canvas.
This feature is implemented using UIPanGestureRecognizer with a specific target action to draw a line in a UIView, but when the “Voice Over” is active the gesture recognizer action is not triggered anymore.
Gesture initialize code
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(pan:)];
pan.maximumNumberOfTouches = pan.minimumNumberOfTouches = 1;
[self addGestureRecognizer:pan];
Gesture action code
- (void)pan:(UIPanGestureRecognizer *)pan {
CGPoint currentPoint = [pan locationInView:self];
CGPoint midPoint = midpoint(previousPoint, currentPoint);
if (pan.state == UIGestureRecognizerStateBegan)
{
[path moveToPoint:currentPoint];
}
else if (pan.state == UIGestureRecognizerStateChanged)
{
[path addQuadCurveToPoint:midPoint controlPoint:previousPoint];
}
previousPoint = currentPoint;
[self setNeedsDisplay];
}
Is there any way to draw a line in a view using gesture with “Voice Over” active?
Thanks and regards!
I resolved my problem setting both isAccessibilityElement and accessibilityTraits properties for UIView canvas:
canvasView.isAccessibilityElement = YES;
canvasView.accessibilityTraits = UIAccessibilityTraitAllowsDirectInteraction;
I have a spriteNode where I need to have swipe detection on a SKSpriteNode, but it seems that swipe gesture can only do on view. Is there a way to do this?
SKSpriteNode *rabbit = [SKSpriteNode spriteNodeWithImageNamed:#"rabbit_img"];
UISwipeGestureRecognizer * swipeleft=[[UISwipeGestureRecognizer alloc]initWithTarget:self action:#selector(handleSwipeGesture:)];
swipeleft.direction=UISwipeGestureRecognizerDirectionLeft;
[self.view addGestureRecognizer:swipeleft];
You can get the starting coordinates of the swipe via the state property.
- (void)swipe:(UISwipeGestureRecognizer *)recognizer
{
CGPoint point = [recognizer locationInView:[recognizer view]];
if (recognizer.state == UIGestureRecognizerStateBegan)
NSLog(#"start coordinates: %#", NSStringFromCGPoint(point));
}
You can then compare those coordinates against your desired nodes using the SKNode method containsPoint: to see if the swipe originated from a node.
I am attempting to run an action in iOS 7 Sprite Kit when the user swipes the left half of the screen.
To accomplish this I created a for loop waiting for touch events and, on touch, there is an if statement that checks to see if the touch location is less than half of the view's bounds. The if statement itself is executing properly (the else half returns the proper NSLog if the touch is initiated on the right half of the screen). The action triggered by the UISwipeGestureRecognizer, however, is called regardless of where the touch is initiated. I have included a code sample below.
Is there is a reason this is not working as expected?
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
for (UITouch *touch in touches) {
CGPoint touchLocation = [touch locationInView:self.view];
NSLog(#"Touch location: %f, %f",touchLocation.x,touchLocation.y);
if (touchLocation.x<self.view.bounds.size.width/2) {
UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:(self) action:#selector(screenSwipedRight)];
swipeRight.numberOfTouchesRequired = 1;
swipeRight.direction=UISwipeGestureRecognizerDirectionRight;
[self.view addGestureRecognizer:(swipeRight)];
UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:(self) action:#selector(screenSwipedLeft)];
swipeLeft.numberOfTouchesRequired = 1;
swipeLeft.direction=UISwipeGestureRecognizerDirectionLeft;
[self.view addGestureRecognizer:(swipeLeft)];
UISwipeGestureRecognizer *swipeUp = [[UISwipeGestureRecognizer alloc] initWithTarget:(self) action:#selector(screenSwipedUp)];
swipeUp.numberOfTouchesRequired = 1;
swipeUp.direction=UISwipeGestureRecognizerDirectionUp;
[self.view addGestureRecognizer:(swipeUp)];
}
else {
NSLog(#"Touches were on the right!");
}
}
}
-(void)screenSwipedRight
{
CGFloat percentToRight = 1-(self.playerOne.position.x / self.view.bounds.size.width);
NSTimeInterval timeToRight = self.horizontalRunSpeed * percentToRight;
NSLog(#"Percent to right = %f",percentToRight);
NSLog(#"Time to right = %f",timeToRight);
SKAction *moveNodeRight = [SKAction moveToX:self.view.bounds.size.width-self.playerOne.size.width duration:timeToRight];
[self.playerOne runAction:[SKAction sequence:#[moveNodeRight]]];
}
Is there is a reason this is not working as expected?
Yes. You are adding a new set of swipe gesture recognizers any time any touch begins on the left half of the screen. You are never removing them. You are never restricting the conditions for the gesture recognizer to begin.
This should fix your issue:
Delete your implementation of touchesBegan:withEvent:.
Add your gesture recognizers in viewDidLoad.
Set delegate = self for all of the gesture recognizers.
Add this code:
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
CGPoint touchLocation = [touch locationInView:self.view];
NSLog(#"Touch location: %f, %f",touchLocation.x,touchLocation.y);
BOOL shouldBegin = (touchLocation.x < self.view.bounds.size.width / 2);
return shouldBegin;
}
I am trying to develop an analysing app that determines if you are "clever"
What this involves doing is taking a picture of yourself and dragging points onto your face, where the nose, mouth and eyes are. However, The code I have tried does not work:
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:self.view];
if ([touch view] == eye1)
{
eye1.center = location;
}
else if ([touch view] == eye2)
{
eye2.center = location;
}
else if ([touch view] == nose)
{
nose.center = location;
}
else if ([touch view] == chin)
{
chin.center = location;
}
else if ([touch view] == lip1)
{
lip1.center = location;
}
else if ([touch view] ==lip2)
{
lip2.center = location;
}
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
[self touchesBegan:touches withEvent:event];
}
What is happening, because when I just have a single image, it works, but is not helpful for me. What can I do to make it work? The spots start at the bottom of the screen in a "Toolbar" and then the user drags them onto the face. I kinda want the finished result to look like:
There are two basic approaches:
You can use the various touches methods (e.g. touchesBegan, touchesMoved, etc.) in your controller or the main view, or you can use a single gesture recognizer on the main view. In this situation, you'd use touchesBegan or, if using a gesture recognizer, a state of UIGestureRecognizerStateBegan, determine locationInView of the superview, and then test whether the touch is over one of your views by testing CGRectContainsPoint, using the frame of the various views as the first parameter, and by using the location as the second parameter.
Having identified the view that the gesture began, then in touchesMoved or, if in a gesture recognizer, a state of UIGestureRecognizerStateChanged, and move the view based upon the translationInView.
Alternatively (and easier IMHO), you can create individual gesture recognizers that you attach to each of the subviews. This latter approach might look like the following. For example, you first add your gesture recognizers:
NSArray *views = #[eye1, eye2, lip1, lip2, chin, nose];
for (UIView *view in views)
{
view.userInteractionEnabled = YES;
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(handlePanGesture:)];
[view addGestureRecognizer:pan];
}
Then you implement a handlePanGesture method:
- (void)handlePanGesture:(UIPanGestureRecognizer *)gesture
{
CGPoint translation = [gesture translationInView:gesture.view];
if (gesture.state == UIGestureRecognizerStateChanged)
{
gesture.view.transform = CGAffineTransformMakeTranslation(translation.x, translation.y);
[gesture.view.superview bringSubviewToFront:gesture.view];
}
else if (gesture.state == UIGestureRecognizerStateEnded)
{
gesture.view.transform = CGAffineTransformIdentity;
gesture.view.center = CGPointMake(gesture.view.center.x + translation.x, gesture.view.center.y + translation.y);
}
}
I am new to iOS, I am using UIPanGestureRecognizer in my project. In which I have a requirement to get current touch point and previous touch point when I am dragging the view. I am struggling to get these two points.
If I use touchesBegan method Instead of using UIPanGestureRecognizer, I could get these two points by the following code:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
CGPoint touchPoint = [[touches anyObject] locationInView:self];
CGPoint previous=[[touches anyObject]previousLocationInView:self];
}
I need to get these two points in UIPanGestureRecognizer event fire method. How can I achieve this? please guide me.
You can use this:
CGPoint currentlocation = [recognizer locationInView:self.view];
Store previous location by setting current location if not found and adding current location everytime.
previousLocation = [recognizer locationInView:self.view];
When you link an UIPanGestureRecognizer to an IBAction, the action will get called on every change. The gesture recognizer also provides a property called state which indicates if it's the first UIGestureRecognizerStateBegan, the last UIGestureRecognizerStateEnded or just an event between UIGestureRecognizerStateChanged.
To solve your problem, try it like the following:
- (IBAction)panGestureMoveAround:(UIPanGestureRecognizer *)gesture {
if ([gesture state] == UIGestureRecognizerStateBegan) {
myVarToStoreTheBeganPosition = [gesture locationInView:self.view];
} else if ([gesture state] == UIGestureRecognizerStateEnded) {
CGPoint myNewPositionAtTheEnd = [gesture locationInView:self.view];
// and now handle it ;)
}
}
You may also have a look at the method called translationInView:.
If you don't want to store anything you can also do this :
let location = panRecognizer.location(in: self)
let translation = panRecognizer.translation(in: self)
let previousLocation = CGPoint(x: location.x - translation.x, y: location.y - translation.y)
There is a function in UITouch to get the previous touch in the view
(CGPoint)locationInView:(UIView *)view;
(CGPoint)previousLocationInView:(UIView *)view;
You should instantiate your pan gesture recognizer as follows:
UIPanGestureRecognizer* panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(handlePan:)];
Then you should add panRecognizer to your view:
[aView addGestureRecognizer:panRecognizer];
The - (void)handlePan:(UIPanGestureRecognizer *)recognizer method will be called while the user interacts with the view. In handlePan: you can get the point touched like this:
CGPoint point = [recognizer locationInView:aView];
You can also get the state of the panRecognizer:
if (recognizer.state == UIGestureRecognizerStateBegan) {
//do something
} else if (recognizer.state == UIGestureRecognizerStateEnded) {
//do something else
}