使用CAShapeLayer与UIBezierPath画出想要的图形

使用CAShapeLayer与UIBezierPath可以实现不在view的drawRect方法中就画出一些想要的图形

步骤：

1、新建UIBezierPath对象bezierPath

2、新建CAShapeLayer对象caShapeLayer

3、将bezierPath的CGPath赋值给caShapeLayer的path，即caShapeLayer.path = bezierPath.CGPath

4、把caShapeLayer添加到某个显示该图形的layer中

下面的小例子是一个环形的progress代码，有具体的使用方法

.h文件：

#import <UIKit/UIKit.h>

@interface KACircleProgressView : UIView {
CAShapeLayer *_trackLayer;
UIBezierPath *_trackPath;
CAShapeLayer *_progressLayer;
UIBezierPath *_progressPath;
}

@property (nonatomic, strong) UIColor *trackColor;
@property (nonatomic, strong) UIColor *progressColor;
@property (nonatomic) float progress;//0~1之间的数
@property (nonatomic) float progressWidth;

- (void)setProgress:(float)progress animated:(BOOL)animated;

@end

.m文件

#import "KACircleProgressView.h"

@implementation KACircleProgressView

- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
_trackLayer = [CAShapeLayer new];
[self.layer addSublayer:_trackLayer];
_trackLayer.fillColor = nil;
_trackLayer.frame = self.bounds;

_progressLayer = [CAShapeLayer new];
[self.layer addSublayer:_progressLayer];
_progressLayer.fillColor = nil;
_progressLayer.lineCap = kCALineCapRound;
_progressLayer.frame = self.bounds;

//默认5
self.progressWidth = 5;
}
return self;
}

- (void)setTrack
{
_trackPath = [UIBezierPath bezierPathWithArcCenter:self.center radius:(self.bounds.size.width - _progressWidth)/ 2 startAngle:0 endAngle:M_PI * 2 clockwise:YES];;
_trackLayer.path = _trackPath.CGPath;
}

- (void)setProgress
{
_progressPath = [UIBezierPath bezierPathWithArcCenter:self.center radius:(self.bounds.size.width - _progressWidth)/ 2 startAngle:- M_PI_2 endAngle:(M_PI * 2) * _progress - M_PI_2 clockwise:YES];
_progressLayer.path = _progressPath.CGPath;
}

- (void)setProgressWidth:(float)progressWidth
{
_progressWidth = progressWidth;
_trackLayer.lineWidth = _progressWidth;
_progressLayer.lineWidth = _progressWidth;

[self setTrack];
[self setProgress];

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
animation.fromValue = [NSNumber numberWithFloat:0.0f];
animation.toValue = [NSNumber numberWithFloat:1.0f];
animation.duration = 3.0f;
[_progressLayer addAnimation:animation forKey:@"myStroke"];
}

- (void)setTrackColor:(UIColor *)trackColor
{
_trackLayer.strokeColor = trackColor.CGColor;
}

- (void)setProgressColor:(UIColor *)progressColor
{
_progressLayer.strokeColor = progressColor.CGColor;
}

- (void)setProgress:(float)progress
{
_progress = progress;

[self setProgress];
}

- (void)setProgress:(float)progress animated:(BOOL)animated
{

}

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/

@end

使用：

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
KACircleProgressView *progress = [[KACircleProgressView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
[self.view addSubview:progress];
progress.trackColor = [UIColor blackColor];
progress.progressColor = [UIColor orangeColor];
progress.progress = .7;
progress.progressWidth = 10;
}

[code][CABasicAnimation animationWithKeyPath:@"strokeEnd"] 中的keyPath不能随意更改。

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check：http://stackoverflow.com/questions/7966590/iphone-core-animation-animate-a-nsbezierpath

也可以参考一份代码：https://github.com/ole/Animated-Paths 其实现的效果在code4app中有介绍http://code4app.com/ios/Animated-Paths/5020854c6803faa152000000

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