I am trying to make a simple landscape "split screen" app where two players can play at once (each player gets one half of the screen), but I am having trouble tracking both touches at the same time. This is the code I am trying to use:
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
for (UITouch *touch in touches) {
CGPoint point = [touch locationInView:self.view];
if (point.x < 240) {
[player1 updatePoint:point];
} else {
[player2 updatePoint:point];
}
}
}
But I am obviously doing something wrong. Although this code works fine, it will only track one finger and move the player on the side of the screen the finger is on. What is my code lacking? Is this task more difficult to pull off then I think it is?
Did you set UIView's multipleTouchEnabled to YES?
multipleTouchEnabled should be set to YES for the UIView.
Related
in my application I'm using touchesMoved method to detect swipe left/right.
when the user swipe to left and right continuously,image animation updates automatically.
I was able to detect swipe action but sometimes when I start to swipe left and right continuously,screen doesn't detect the touchmoved event.
in the swipe area I have placed one hidden button and few ImageViews for animations.
I want to know why it happens.please help me.
thank you.
code:
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
[super touchesMoved:touches withEvent:event];
UITouch *touch = [touches anyObject];
CGPoint newLocation = [touch locationInView:self.view];
CGPoint oldLocation = [touch previousLocationInView:self.view];
if(newLocation.x-oldLocation.x>0){
swipe_direction = 1;
//NSLog(#"left");
}
else{
swipe_direction = 2;
//NSLog(#"right");
}
if(swipe_direction == 1){
//animate images
}
else if(swipe_direction == 2){
//animate images
}
}
touchesMoved Only detects on the empty part of the View. Therefore, it will not detect over the objects you used.
Place a SwipeGestureRecognizer over the view and use it from there.
Have you considered using a SwipeGestureRecognizer instead of the touchesMoved?
Check the Documentation
I'm having a problem with a jumping movement with using CGAffineTransformMakeRotation. It seems to work fine until I get to the top of quadrants 1 and 2. Below is the code I am using and youtube link that shows what happens. Any insight would be really appreciated.
My goal is to rotate a UIWebView with an svg inside. Since I can't easily detect touch on the UIWebView alone, I'm putting a blank UIImageView over it. This allows me to detect the touch and prevent the copy dialog from popping up.
http://www.youtube.com/watch?v=x_OmS0MPdEE&feature=youtu.be
- (void)touchesMoved: (NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
NSArray *allTouches = [touches allObjects];
CGPoint location = [[allTouches objectAtIndex:0] locationInView:self.view];
if(selected == 1) {
CGFloat rads = atan2f(location.y - (grid1.frame.size.height/2),location.x - (grid1.frame.size.width/2));
grid1.transform = grid1Btn.transform = CGAffineTransformMakeRotation(rads);
}
}
- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
NSArray *allTouches = [touches allObjects];
CGPoint location = [[allTouches objectAtIndex:0] locationInView:self.view];
if(CGRectContainsPoint(grid1Btn.frame, location))
{
selected = 1;
}
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
selected = -1;
}
You use some frame.size.* in your computations. Note, that those values (unlike bounds.size.*) are affected by transform. Use grid1.center instead. It is also more logical (you rotate around center).
The next thing you need to fix is that it should not jump to new position when touches start :)
The jerkiness is caused by the inherent inaccuracy of touch event locations.
Touch events that are located sufficiently close to the center of the frame have a high likelihood of straying to the diagonally opposite quadrant of the frame whilst a circle is being traced about the center of the frame.
This will result in a sudden jump of 90 degrees as observed in your video.
One way to avoid the problem is to introduce a dead zone about the center of the frame. Any touch that is located within a given radius of the center of the frame would not trigger the rotation to be recalculated.
Hope this helps.
I spend quite some time to figure out how to achieve what I want to do but didn't find a proper solution for it, yet. I have a UIScrollView where I changed the panGestureRecognizer from one to two finger recognition so the paging only works when two fingers are used. Now I want to add an additional panGestureRecognizer that shows a courser if I'm panning with one finger. I tried that by just adding an additional panGestureRecognizer to the UIScrollView but then the app crashes immediately. So I thought of adding a subview that is transparent and positioned above the UIScrollView and that I delegate the two finger gestures to the UIScrollView with something like resgin firstResponder. I also thought of overwriting the pangestureRecognizer of the UIScrollView and let it add a Subview where my "fingerpointer"(a little point that is centered where I'm touching the screen right now) is located. I'm totally clueless what way I should go and how to implement it. Your help is greatly appreciated! Thanks a lot!
Timo
Ok, this is the second time editing my response. This might do the trick for you.
If you extend UIScrollView you can override these methods in this way:
//In your h file
BOOL cursorShown;
//In your m file
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
if([touches count] == 1)
{
cursorShown = YES;
CGPoint touchLocation = [[touches anyObject] locationInView:self.superview]
//Add your cursor to the parent view here and set its location to touchLocation
}
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
if(cursorShown == YES)
{
CGPoint touchLocation = [[touches anyObject] locationInView:self.superview]
//Move your cursors location to touchLocation
}
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if(cursorShown == YES)
{
cursorShown = NO;
//Destroy your cursor
}
}
-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
if(cursorShown == YES)
{
cursorShown = NO;
//Destroy your cursor
}
}
I'm having some images from which the user should choose one. Now I don't want to just offer an flat scrolling area with a boring grid. Instead, I'd like to show up a wheel that contains those images. At the top would be a marker indicating the selection. Something similar to the Pickers.
The problem is not the rotation stuff; I'd use some geometric functions for that. But I have no idea how to actually get the scrolling gestures on that wheel. Where must I start?
BTW: With circular I don't mean something like the Pickers. I mean a real wheel that has a center axis and can be rolled. Like the very old telephones, like a bike wheel. Or a Picker turned by 90°, facing with the axis to you (Z-coordinate).
If you're talking about capturing gestures then here is the example they give in the docs.
Though I could have sworn I heard Alan Cannistraro say in one of the first CS193P lectures that you don't have to do this, that you can just trap the swipe event but I can't find that.
Could someone that actually knows what they are doing please correct me and I'll remove this post but for now I know this will work:
#define HORIZ_SWIPE_DRAG_MIN 12
#define VERT_SWIPE_DRAG_MAX 4
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
startTouchPosition = [touch locationInView:self];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint currentTouchPosition = [touch locationInView:self];
// If the swipe tracks correctly.
if (fabsf(startTouchPosition.x - currentTouchPosition.x) >= HORIZ_SWIPE_DRAG_MIN &&
fabsf(startTouchPosition.y - currentTouchPosition.y) <= VERT_SWIPE_DRAG_MAX)
{
// It appears to be a swipe.
if (startTouchPosition.x < currentTouchPosition.x)
[self myProcessRightSwipe:touches withEvent:event];
else
[self myProcessLeftSwipe:touches withEvent:event];
}
else
{
// Process a non-swipe event.
}
}
Just how similar to a picker view are you thinking? You can load up a picker view with your own custom subviews, which could be image views. That'd get you an actual picker view with your images, which might or might not be what you're actually aiming for.
I have a grid of images/buttons, and I want the user to be able to drag their finger over the images/buttons such that when their finger touches each image/button an event is called.
How do I do this???
The best example I can think of now is the Contacts app, how you drag your finger down the list of letters (on the right) and as you touch each letter it jumps to that part of the contacts list.
You're going to want to implement -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event in your UIViewController. This method is called any time a touch moves on the screen. You can then either use the coordinates (use [myUITouch locationInView:self.view]) or [self.view.layer hitTest:[myUITouch locationInView:self.view]] to get the image/button the touch occurred in and work from that.
For example, if I have a row of ten images, each 32 pixels by 32 pixels, and I want to record when each of them is touched, I could do something like the following:
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
CGSize buttonSize = myButton.bounds.size;
CGPoint touchPoint = [[touches anyObject] locationInView:self.view];
if (touchPoint.y < buttonSize.y) {
NSInteger buttonNumber = touchPoint.x/buttonSize.x;
NSLog(#"Button number %d pushed", buttonNumber);
}
}
Note this assumes multitouch is disabled or it will randomly pick one touch to record