How to draw line with animation in iPhone - iphone

Question

I am drawing line in iphone using CGContextRef. Can any one suggest me how i draw line with animation in iphone.
Please suggest.

Answer 1

Here is the answer (found here : http://soulwithmobiletechnology.blogspot.fr/2012/07/how-to-animate-line-draw.html)
UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointMake(50.0,0.0)];
[path addLineToPoint:CGPointMake(120.0, 600.0)];
CAShapeLayer *pathLayer = [CAShapeLayer layer];
pathLayer.frame = self.view.bounds;
pathLayer.path = path.CGPath;
pathLayer.strokeColor = [[UIColor redColor] CGColor];
pathLayer.fillColor = nil;
pathLayer.lineWidth = 2.0f;
pathLayer.lineJoin = kCALineJoinBevel;
[self.view.layer addSublayer:pathLayer];
CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
pathAnimation.duration = 2.0;
pathAnimation.fromValue = [NSNumber numberWithFloat:0.0f];
pathAnimation.toValue = [NSNumber numberWithFloat:1.0f];
[pathLayer addAnimation:pathAnimation forKey:#"strokeEnd"];
Do not forget to #import <QuartzCore/QuartzCore.h>.

Answer 2

Is it a straight line?.. You can use a 1 pixel wide UIView and animate its frame property. Using [UIView beginAnimations] and [UIView commitAnimations]; Otherwise, see this post.
Edited response
Using core animation, you can do something like this (e.g. behind a button)
CABasicAnimation *theAnimation = [self pathAnimation];
theAnimation.duration=3.0;
theAnimation.autoreverses=YES;
[[self layer] addAnimation:theAnimation forKey:#"animatePath"];
Path animation is defined as:
- (CAAnimation*)pathAnimation;
{
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path,NULL,50.0,120.0);
CGPathAddCurveToPoint(path,NULL,50.0,275.0,
150.0,275.0,
150.0,120.0);
CGPathAddCurveToPoint(path,NULL,150.0,275.0,
250.0,275.0,
250.0,120.0);
CGPathAddCurveToPoint(path,NULL,250.0,275.0,
350.0,275.0,
350.0,120.0);
CGPathAddCurveToPoint(path,NULL,350.0,275.0,
450.0,275.0,
450.0,120.0);
CAKeyframeAnimation *
animation = [CAKeyframeAnimation
animationWithKeyPath:#"position"];
[animation setPath:path];
[animation setDuration:3.0];
[animation setAutoreverses:YES];
CFRelease(path);
return animation;
}
This is only a pointer to what you can do with Core Animation. See this article for detail.

Answer 3

The Swift 3 version of Martin's answer (checked with Xcode 8.3.3)
let path = UIBezierPath()
path.move(to: CGPoint(x: 50, y: 0))
path.addLine(to: CGPoint(x: 120, y: 600))
let pathLayer = CAShapeLayer()
pathLayer.frame = view.bounds
pathLayer.path = path.cgPath
pathLayer.strokeColor = UIColor.red.cgColor
pathLayer.fillColor = nil
pathLayer.lineWidth = 2
pathLayer.lineJoin = kCALineJoinBevel
view.layer.addSublayer(pathLayer)
let pathAnimation = CABasicAnimation(keyPath: "strokeEnd")
pathAnimation.duration = 2.0
pathAnimation.fromValue = 0
pathAnimation.toValue = 1
pathLayer.add(pathAnimation, forKey: "strokeEnd")