Drawing straight lines when touched moved IOS - iphone

Question

I have planned to do simple drawing up, using that use can draw straight lines and free hand drawing, based on the selection it change. But the problem is straight line gets repeated from the starting point more than 10 or 15 lines when i try to draw 1 line, free hand drawing working fine.I have posted my code here. Please give your suggestions to fix this issue.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
mouseSwiped = NO;
UITouch *touch = [touches anyObject];
previousPoint1 = [touch previousLocationInView:self.view];
previousPoint2 = [touch previousLocationInView:self.view];
currentPoint = [touch locationInView:self.view];
lastPoint = [touch locationInView:self.view];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
// Work download Flag
_isWorkModified = YES;
mouseSwiped = YES;
UITouch *touch = [touches anyObject];
previousPoint2 = previousPoint1;
previousPoint1 = [touch previousLocationInView:self.view];
currentPoint = [touch locationInView:self.view];
UIGraphicsBeginImageContext(self.view.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
if(_selectedShape == 3)
{
// calculate mid point
CGPoint mid1 = [self midPoint:previousPoint1 :previousPoint2];
CGPoint mid2 = [self midPoint:currentPoint :previousPoint1];
CGContextMoveToPoint(context, mid1.x, mid1.y);
CGContextAddQuadCurveToPoint(context, previousPoint1.x, previousPoint1.y, mid2.x, mid2.y);
CGContextSetLineCap(context, kCGLineCapRound);
if(self.isEraseButtonSelected)
{
CGContextSetLineWidth(context, 40.0);
CGContextSetRGBStrokeColor(context, 0.823,0.886,0.898,1.0);
}
else
{
CGContextSetLineWidth(context, 3.0);
CGContextSetRGBStrokeColor(context, 0.0, 0.0, 0.0, 1.0);
}
CGContextStrokePath(context);
}
else if(_selectedShape == 0)
{
CGContextSetLineWidth(context, 3.0);
CGContextSetRGBStrokeColor(context, 0.0, 0.0, 0.0, 1.0);
CGContextBeginPath(context);
CGContextMoveToPoint(context, lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(context, currentPoint.x, currentPoint.y);
CGContextClosePath(context);
CGContextStrokePath(context);
}
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"touch ended");
if(!mouseSwiped)
{
NSInteger index = [[[AnswerDataHandler getAnswerDataHandler]workAreaArray] indexOfObject:self];
[[ImageStoreHelper getImageStoreHelper] saveImageForQuestionNumber:index image:drawImage.image];
}
}
}