How we erase Line - ios

Question

I want to make erase button on click we erase line on moving the line . But I am Unable to do it. I am successfully implemented of code of create d Line. But stuck how to erase Line. I am newer in iOS. Here is my code. Please help
#implementation Line
{
UIBezierPath *path;
UIImage *incrementalImage; // (1)
}
- (id)initWithCoder:(NSCoder *)aDecoder
{
if (self = [super initWithCoder:aDecoder])
{
[self setMultipleTouchEnabled:NO];
[self setBackgroundColor:[UIColor whiteColor]];
path = [UIBezierPath bezierPath];
[path setLineWidth:2.0];
}
return self;
}
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[self setMultipleTouchEnabled:NO];
path = [UIBezierPath bezierPath];
[path setLineWidth:1.0];
self.backgroundColor=[UIColor clearColor];
_button = [UIButton buttonWithType:UIButtonTypeCustom];
[_button setTitle:#"" forState:UIControlStateNormal];
_button.userInteractionEnabled=YES;
_button.frame =CGRectMake(100, 130, 100, 100);
_button.backgroundColor =[ UIColor redColor];
[_button addTarget:self
action:#selector(erase)
forControlEvents:UIControlEventTouchUpInside];
[self addSubview:_button];
}
return self;
}
- (void)drawRect:(CGRect)rect
{
[incrementalImage drawInRect:rect]; // (3)
[path stroke];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[path moveToPoint:p];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[path addLineToPoint:p];
[self setNeedsDisplay];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event // (2)
{
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[path addLineToPoint:p];
[self drawBitmap]; // (3)
[self setNeedsDisplay];
[path removeAllPoints]; //(4)
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
[self touchesEnded:touches withEvent:event];
}
- (void)drawBitmap // (3)
{
UIGraphicsBeginImageContextWithOptions(self.bounds.size, YES, 0.0);
[[UIColor blackColor] setStroke];
if (!incrementalImage) // first draw; paint background white by ...
{
UIBezierPath *rectpath = [UIBezierPath bezierPathWithRect:self.bounds]; // enclosing bitmap by a rectangle defined by another UIBezierPath object
[[UIColor whiteColor] setFill];
[rectpath fill]; // filling it with white
}
[incrementalImage drawAtPoint:CGPointZero];
[path stroke];
incrementalImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
-(void)erase
{
NSLog(#"erasingLIne");
}

Answer 1

Take a BOOL value for erase. BOOL isErase;
when erase button tapped
if button tapped
{
isErase =Yes;
}else
{
isErase = NO;
}
[path strokeWithBlendMode:isErase?kCGBlendModeClear:kCGBlendModeNormal
alpha:1.0f];
Hope it works for you.