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 <QuartzCore/QuartzCore.h>  #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];  }  - (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：[cpp] view plain copy- (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;  }