iOS 熟悉CASharpLayer

1. 代码示例

- (void)viewDidLoad {

    [super viewDidLoad];

    CAShapeLayer *shape = [CAShapeLayer layer];

    UIBezierPath *bezierPath = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(100, 100, 200, 200) cornerRadius:98];

    shape.path = bezierPath.CGPath;

    shape.fillColor = [UIColor clearColor].CGColor;

    shape.strokeColor = [UIColor blueColor].CGColor;

    shape.lineWidth = 4.f;

    shape.strokeStart = 0.f;

    shape.strokeEnd = 0.7f;

    [self.view.layer addSublayer:shape];

    self.shape = shape;

}

- (IBAction)btn:(id)sender {

    CGFloat text = (arc4random()%100)/100.f;

    NSLog(@"====%f",text);

    self.shape.strokeStart = text;

}

2. 顶部端是strokeStart,左下端是strokeEnd

2.1. 当strokeStart>strokeEnd，shapeLayer无法显示

2.2. strokeStart,strokeEnd的取值范围都再0-1之间，包含0，1

2.3. 改变strokeStart或strokeEnd，会触发shapeLayer的隐式动画