如何使用多点触控正确显示两个图像的高光？

Question

I have problem with custom double slider. There are two images which are thumbs. Application works fine, both thumbs can move using both fingers, but there are problem with highlight .

When I take off finger from one thumb, highlight from second thumb also back to normal. When I'm using any if and else statment, it brings another bad results: sometimes highlight not changes or stay when finger move out from image. Or blinks.

I have no idea, how to continue work, to bind highlight with endTouches event properly. To not highlight thumbs, if not pressed. How to solve to?

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

   for(UITouch *touch in [event allTouches]) {

       CGPoint touchPoint = [touch locationInView:self];
       if(CGRectContainsPoint(thumbLeft.frame, touchPoint)){
           thumbLeft.highlighted = YES;
       }
       if(CGRectContainsPoint(thumbRight.frame, touchPoint)){
           thumbRight.highlighted = YES;
       }

    }
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {

    //No idea here
    for(UITouch *touch in [event allTouches]) {
        CGPoint touchPoint = [touch locationInView:self];


        //----------- ???? ----------//

        thumbRight.highlighted = NO;
        thumbLeft.highlighted = NO;

    }
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{

    for(UITouch *touch in [event allTouches]) {

        CGPoint touchPoint = [touch locationInView:self];
        if (CGRectContainsPoint(thumbLeft.frame, touchPoint)){
            thumbLeft.center = CGPointMake(MAX(barLeftHorizontalPosition, MIN(touchPoint.x, thumbRight.center.x - minimumRange)), thumbLeft.center.y);
            thumbLeft.highlighted = YES;
            valueLeft = [self valueGetX:thumbLeft.center.x];
        }

        if (CGRectContainsPoint(thumbRight.frame, touchPoint)){
            thumbRight.center = CGPointMake(MAX(thumbLeft.center.x + minimumRange, MIN(touchPoint.x, barRightHorizontalPosition)), thumbRight.center.y);
            thumbRight.highlighted = YES;
            valueRight = [self valueGetX:thumbRight.center.x];
        }

        [self sendActionsForControlEvents:UIControlEventValueChanged];
    }
}

Answer 1

I think the issue is not on the touchesEnded , but on touchesMoved method.

You should implement the logic back into touchesEnded:

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    for(UITouch *touch in [event allTouches]) {
        CGPoint touchPoint = [touch locationInView:self];
        if(CGRectContainsPoint(thumbLeft.frame, touchPoint)){
            thumbLeft.highlighted = NO;
        }
        if(CGRectContainsPoint(thumbRight.frame, touchPoint)){
            thumbRight.highlighted = NO;
        }
    }
}

and also make touchesMoved handle setting NO on the highlight:

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
    for(UITouch *touch in [event allTouches]) {
        CGPoint touchPoint = [touch locationInView:self];

        if (CGRectContainsPoint(thumbLeft.frame, touchPoint)){
            thumbLeft.center = CGPointMake(MAX(barLeftHorizontalPosition, MIN(touchPoint.x, thumbRight.center.x - minimumRange)), thumbLeft.center.y);
            thumbLeft.highlighted = YES;
            valueLeft = [self valueGetX:thumbLeft.center.x];
        } else {
            thumbLeft.highlighted = NO;
        }

        if (CGRectContainsPoint(thumbRight.frame, touchPoint)){
            thumbRight.center = CGPointMake(MAX(thumbLeft.center.x + minimumRange, MIN(touchPoint.x, barRightHorizontalPosition)), thumbRight.center.y);
            thumbRight.highlighted = YES;
            valueRight = [self valueGetX:thumbRight.center.x];
        } else {
            thumbRight.highlighted = NO;
        }

        [self sendActionsForControlEvents:UIControlEventValueChanged];
    }
}