畫線動(dòng)畫

- (void)viewDidLoad{
    UIBezierPath *path=[UIBezierPath bezierPath];
    [path moveToPoint:CGPointZero];
    [path addLineToPoint:CGPointMake(200, 200)];
    CAShapeLayer *layer=[CAShapeLayer layer];
    layer.fillColor=[UIColor clearColor].CGColor;
    layer.strokeColor=[UIColor redColor].CGColor;
    layer.path=path.CGPath;
    layer.lineWidth = 2;
    layer.strokeEnd = 0;
    layer.frame=CGRectMake(100, 100, 200, 200);
    [self.view.layer addSublayer:layer];
    
    dispatch_async(dispatch_get_main_queue(), ^{
//        [CATransaction begin];
//        [CATransaction setAnimationDuration:5.0];
        layer.strokeEnd=1;
//        [CATransaction commit];
    });
}

CALayer的Animatable屬性
當(dāng)設(shè)置一個(gè)獨(dú)立的CALayer(或子類)對(duì)象的Animatable屬性時(shí)，系統(tǒng)會(huì)自動(dòng)生成隱式動(dòng)畫；而與UIView關(guān)聯(lián)的CALayer對(duì)象不會(huì)生成隱式動(dòng)畫。隱式動(dòng)畫可通過CATransaction類管理。