普通CALayer在被初始化時(shí)是需要給一個(gè)frame值的,這個(gè)frame值一般都與給定view的bounds值一致,它本身是有形狀的,而且是矩形.
CAShapeLayer在初始化時(shí)也需要給一個(gè)frame值,但是,它本身沒有形狀,它的形狀來(lái)源于你給定的一個(gè)path,然后它去取CGPath值,它與CALayer有著很大的區(qū)別
CAShapeLayer有著幾點(diǎn)很重要:
- 它依附于一個(gè)給定的path,必須給與path,而且,即使path不完整也會(huì)自動(dòng)首尾相接
- strokeStart以及strokeEnd代表著在這個(gè)path中所占用的百分比
CAShapeLayer動(dòng)畫僅僅限于沿著邊緣的動(dòng)畫效果,它實(shí)現(xiàn)不了填充效果
"CyleView.h"
@interface CyleView : UIView
{
CAShapeLayer *layer;
}
- (void)strokeStart:(CGFloat)value;
- (void)strokeEnd:(CGFloat)value;
@end
"CyleView.m"
@implementation CyleView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self)
{
layer = [CAShapeLayer layer];
layer.frame = self.bounds;
UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(self.frame.size.height / 2.0f,
self.frame.size.height / 2.0f)
radius:self.frame.size.height / 2.f
startAngle:0
endAngle:M_PI * 2
clockwise:YES];
layer.strokeColor = [UIColor orangeColor].CGColor; // 邊緣線的顏色
layer.fillColor = [UIColor clearColor].CGColor; // 閉環(huán)填充的顏色
layer.lineCap = kCALineCapRound; // 邊緣線的類型
layer.path = path.CGPath; // 從貝塞爾曲線獲取到形狀
layer.lineWidth = 5.0f; // 線條寬度
layer.strokeStart = 0.0f;
layer.strokeEnd = 0.0f;
/*
如果默認(rèn)是一個(gè)圓圈
layer.strokeStart = 0.0;
layer.strokeEnd = 1.0;
*/
[self.layer addSublayer:layer];
}
return self;
}
- (void)strokeStart:(CGFloat)value
{
layer.speed = 1;
layer.strokeStart = value;
}
- (void)strokeEnd:(CGFloat)value
{
layer.speed = 1;
layer.strokeEnd = value;
}
@end
