实现思路:
UIBezierPath勾勒轮廓,CAShapeLayer按照轮廓画出形状,CAGradientLayer做颜色渐变,让CAShapeLayer做CAGradientLayer的遮罩mask,
#import "ViewController.h"
@interface ViewController ()
@property (nonatomic,strong) CAShapeLayer *shapLayer;
@property (nonatomic,strong) CAGradientLayer *gradientLayer;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self.gradientLayer setMask:self.shapLayer];
[self.view.layer addSublayer:self.gradientLayer];
[self drawCircleAnimation:self.shapLayer];
}
- (CAShapeLayer*)shapLayer{
if(_shapLayer==nil) {
CGSize size = self.view.bounds.size;
UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(size.width/2, size.height/2) radius:size.width/2 - 1 startAngle:M_PI endAngle:M_PI * 2 clockwise:YES];
_shapLayer= [CAShapeLayerlayer];
_shapLayer.path= path.CGPath;
_shapLayer.fillColor= [[UIColorclearColor]CGColor];
_shapLayer.strokeColor= [[UIColorredColor]CGColor];
_shapLayer.lineWidth=1;
_shapLayer.lineCap = kCALineCapRound;
}
return _shapLayer;
}
- (CAGradientLayer*)gradientLayer{
if (_gradientLayer == nil) {
CGSize size = self.view.bounds.size;
_gradientLayer = [CAGradientLayer layer];
_gradientLayer.frame=CGRectMake(0,0, size.width, size.width);
_gradientLayer.backgroundColor = [[UIColor grayColor] CGColor];
_gradientLayer.colors = @[(__bridge id)[UIColor redColor].CGColor,
(__bridgeid)[UIColorgreenColor].CGColor,
(__bridgeid)[UIColoryellowColor].CGColor,
(__bridgeid)[UIColorblueColor].CGColor];
_gradientLayer.locations =@[@(0.2), @(0.4), @(0.6),@(0.8)];
_gradientLayer.startPoint=CGPointMake(0,0);
_gradientLayer.endPoint=CGPointMake(1,0);
}
return _gradientLayer;
}
- (void)drawCircleAnimation:(CALayer*)lay
{
CABasicAnimation *baseAnimation=[CABasicAnimation animationWithKeyPath:@"strokeEnd"];
baseAnimation.duration=5.0;
baseAnimation.fromValue=[NSNumber numberWithInteger:0];
baseAnimation.toValue=[NSNumber numberWithInteger:1.0];
[layaddAnimation:baseAnimation forKey:@"circleKey"];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
