Is there any function or algorithm to catch all the points when drawing in iPhone? Like in Android, where we have gethistoical points.
Check the methods touchesBegan:withEvent:, touchesMoved:withEvent:, touchesEnded:withEvent: and touchesCancelled:withEvent: to detect movements
For example using the method -touchesMoved:withEvent:
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint currentPosition = [touch locationInView:self.view];
NSLog(#"%#", NSStringFromCGPoint(currentPosition));
}
For more info check the documentation of the UIResponder class
Related
Hi I want to move a uibutton where even I want in my app like we have Assistive touch in iphone so as a same I want that kind of button in my app..Is it possible to do that If so please help out with code are some links for that
This question is asked so many times.... here is answer
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint touchLocation = [touch locationInView:self.view];
button.frame.x = touchlocation.x;
button.frame.y = touchlocation.y;
}
I feel strange, I have dark view(darkScreenView) and green view.
I using the
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches] anyObject];
CGPoint touchViewPoint = [touch locationInView:touch.view];
NSLog(#"[self.darkScreenView pointInside:touchViewPoint withEvent:event]:%d",[self.darkView pointInside:touchViewPoint withEvent:event]);
}
When I click on the dark view or green view,
The Log still show 1. why?
I click on the green view should show log 0, but I still get the log result 1.
I am using xcode 6.3.1.
Have anyone know what problem in this situation?
Thank you~
This will work
UITouch *touch = [[event allTouches] anyObject];
CGPoint touchViewPoint = [touch locationInView:touch.view];
CGPoint pointOfDarkView = [touch.view convertPoint:touchViewPoint toView:self.darkview];
NSLog(#"[self.darkScreenView pointInside:touchViewPoint withEvent:event]:%d",[self.darkview pointInside:pointOfDarkView withEvent:event]);
Your problem:
touchViewPoint is relative to touch.view coordinate
You have to convert point to darkview coordinate first,then you can use pointInside:pointOfDarkView
Try to get touch for different views..
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches] anyObject];
if (touch.view==GREEN_VIEW)
{
//Write your code for green view here
}
else if(touch.view==DARK_VIEW)
{
//Write your code for dark view here
}
}
Your touchViewPoint's location is relative to the touched view. So get location relative to self.darkView like below.
CGPoint touchViewPoint = [touch locationInView: self.darkView];
Here is the problem change to View you are referring to.
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches] anyObject];
CGPoint touchViewPoint = [touch locationInView:darkView]; <----- Problem
NSLog(#"[self.darkScreenView pointInside:touchViewPoint withEvent:event]:%d",[self.darkView pointInside:touchViewPoint withEvent:event]);
}
I created a very simple app that contains a draggable UIImageView but I faced a problem that the image can be dragged without touching it. I'm sure that the hole issue is from anyObject but I have no idea how to replace it I tried self.view.image but it failed. So here's my code
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];
lineView.center = location;
}
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
[self touchesBegan:touches withEvent:event];
}
any ideas?
Consider using a pan gesture recogniser. Add it only to the image view (and enable user interaction on the view). Now you will only get action method callbacks from the gesture when the view has actually been touched, your code becomes simpler, and you can move the view with that position.
Also, in your current code, it's weird to call touchesBegan: from touchesMoved:. If you keep that code (because you don't want to use a gesture), you should refactor the code that moves the view out into a different method and have both touchesBegan: and touchesMoved: call that method.
Try the following
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];
if ([lineView pointInside:location withEvent:event])
lineView.center = location;
}
Is there any function or algorithm to catch all the points when drawing in iPhone? Like in Android, where we have gethistoical points.
Check the methods touchesBegan:withEvent:, touchesMoved:withEvent:, touchesEnded:withEvent: and touchesCancelled:withEvent: to detect movements
For example using the method -touchesMoved:withEvent:
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint currentPosition = [touch locationInView:self.view];
NSLog(#"%#", NSStringFromCGPoint(currentPosition));
}
For more info check the documentation of the UIResponder class
I'm studying Quartz now and want to do a demo like this:
when your finger moves on the iPhone screen, it shows the track in red color。
The code is like:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch = [touches anyObject];
_firstPoint = [touch locationInView:self];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch = [touches anyObject];
_endPoint = [touch locationInView:self];
[self setNeedsDisplay];
_firstPoint = _endPoint;
}
then
- (void)drawRect:(CGRect)rect {
// Drawing code.
CGContextRef _context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(_context, 1, 0, 0, 1);
CGContextMoveToPoint(_context, _firstPoint.x, _firstPoint.y);
CGContextAddLineToPoint(_context, _endPoint.x, _endPoint.y);
CGContextStrokePath(_context);
}
Here,_firstPoint and _endPoint are CGPoint to record positions.
However, it doesn't show the track.
I don't know what is the problem.
Please give any tips.
Finally, I'd like to consultant whether it is right to fulfill such a kind of App.
thanks!
To your point about where the collection of points making up the lines is stored, it is not stored in this example.
EDITED
Yeah, to store them, I'd just add to a NSMutableArray.
something like
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
if (!_points) _points = [[NSMutableArray array] retain];
UITouch *touch = [touches anyObject];
[_points addObject:[NSValue valueWithCGPoint:[touch locationInView:self]];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
[_points addObject:[NSValue valueWithCGPoint:[touch locationInView:self]];
[self setNeedsDisplay];
}
The setNeedsDisplay is going to invoke the drawRect that's where you use the points and your draw methods.
you can read this tutorial to figured it out - may be it helps
http://www.ifans.com/forums/showthread.php?t=132024
i think you missed CGContextBeginPath(...) first of all
good luck!