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：

 1 #import <UIKit/UIKit.h>
 2 
 3 @interface KACircleProgressView : UIView {
 4     CAShapeLayer *_trackLayer;
 5     UIBezierPath *_trackPath;
 6     CAShapeLayer *_progressLayer;
 7     UIBezierPath *_progressPath;
 8 }
 9 
10 @property (nonatomic, strong) UIColor *trackColor;
11 @property (nonatomic, strong) UIColor *progressColor;
12 @property (nonatomic) float progress;//0~1之间的数
13 @property (nonatomic) float progressWidth;
14 
15 - (void)setProgress:(float)progress animated:(BOOL)animated;
16 
17 @end

.m文件

 1 #import "KACircleProgressView.h"
 2 
 3 @implementation KACircleProgressView
 4 
 5 - (id)initWithFrame:(CGRect)frame
 6 {
 7     self = [super initWithFrame:frame];
 8     if (self) {
 9         // Initialization code
10         _trackLayer = [CAShapeLayer new];
11         [self.layer addSublayer:_trackLayer];
12         _trackLayer.fillColor = nil;
13         _trackLayer.frame = self.bounds;
14         
15         _progressLayer = [CAShapeLayer new];
16         [self.layer addSublayer:_progressLayer];
17         _progressLayer.fillColor = nil;
18         _progressLayer.lineCap = kCALineCapRound;
19         _progressLayer.frame = self.bounds;
20         
21         //默认5
22         self.progressWidth = 5;
23     }
24     return self;
25 }
26 
27 - (void)setTrack
28 {
29     _trackPath = [UIBezierPath bezierPathWithArcCenter:self.center radius:(self.bounds.size.width - _progressWidth)/ 2 startAngle:0 endAngle:M_PI * 2 clockwise:YES];;
30     _trackLayer.path = _trackPath.CGPath;
31 }
32 
33 - (void)setProgress
34 {
35     _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];
36     _progressLayer.path = _progressPath.CGPath;
37 }
38 
39 
40 - (void)setProgressWidth:(float)progressWidth
41 {
42     _progressWidth = progressWidth;
43     _trackLayer.lineWidth = _progressWidth;
44     _progressLayer.lineWidth = _progressWidth;
45     
46     [self setTrack];
47     [self setProgress];
48     
49     CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
50     animation.fromValue = [NSNumber numberWithFloat:0.0f];
51     animation.toValue = [NSNumber numberWithFloat:1.0f];
52     animation.duration = 3.0f;
53     [_progressLayer addAnimation:animation forKey:@"myStroke"];
54 }
55 
56 - (void)setTrackColor:(UIColor *)trackColor
57 {
58     _trackLayer.strokeColor = trackColor.CGColor;
59 }
60 
61 - (void)setProgressColor:(UIColor *)progressColor
62 {
63     _progressLayer.strokeColor = progressColor.CGColor;
64 }
65 
66 - (void)setProgress:(float)progress
67 {
68     _progress = progress;
69     
70     [self setProgress];
71 }
72 
73 - (void)setProgress:(float)progress animated:(BOOL)animated
74 {
75     
76 }
77 
78 /*
79  // Only override drawRect: if you perform custom drawing.
80  // An empty implementation adversely affects performance during animation.
81  - (void)drawRect:(CGRect)rect
82  {
83  // Drawing code
84  }
85  */
86 
87 @end

使用：

 1 - (void)viewDidLoad
 2 {
 3     [super viewDidLoad];
 4     // Do any additional setup after loading the view, typically from a nib.
 5     KACircleProgressView *progress = [[KACircleProgressView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
 6     [self.view addSubview:progress];
 7     progress.trackColor = [UIColor blackColor];
 8     progress.progressColor = [UIColor orangeColor];
 9     progress.progress = .7;
10     progress.progressWidth = 10;
11 }

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

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