自动旋转渐变圆环

//.h文件#import <UIKit/UIKit.h>@interface CirlceView : UIView/**线宽**/- (instancetype)initWithFrame:(CGRect)frame lineWidth:(CGFloat)lineWidth;/**改变圆环颜色**/- (void)changeColor:(UIColor *)color Step:(NSInteger)step;/**添加动画**/- (void)addRatateAnimation;/**改变旋转速度 0~1**/- (void)changeSpeed:(CGFloat)value;@end//.m文件#import "CirlceView.h"@interface CirlceView (){    CAShapeLayer *_trackLayer;    CALayer *_gradientLayer;    CAGradientLayer *_gradientLayer1;    CAGradientLayer *_gradientLayer2;    CAGradientLayer *_gradientLayer3;    CAGradientLayer *_gradientLayer4;    CAShapeLayer *_progressLayer;    CABasicAnimation *_animation;    CGFloat _lineWidth;    UIColor *cor1;    UIColor *cor2;    UIColor *cor3;    UIColor *cor4;}@end@implementation CirlceView- (instancetype)initWithFrame:(CGRect)frame lineWidth:(CGFloat)lineWidth{    self = [super initWithFrame:frame];    if (self) {        [self setDefault];        _lineWidth = lineWidth;        [self drawRing];    }    return self;}- (void)setDefault{    _lineWidth = 30;    cor1 = [UIColor redColor];    cor2 = [UIColor yellowColor];    cor3 = [UIColor greenColor];    cor4 = [UIColor blueColor];}- (void)drawRing{    CGFloat w = self.frame.size.width/2.0;    CGFloat h = self.frame.size.height/2.0;    CGFloat scale = _lineWidth/w;    _trackLayer = [CAShapeLayer layer];    _trackLayer.frame = self.bounds;    _trackLayer.fillColor = [UIColor clearColor].CGColor;    _trackLayer.strokeColor = [UIColor redColor].CGColor;    _trackLayer.lineWidth = _lineWidth;    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(self.frame.size.width/2.0, self.frame.size.height/2.0) radius:w-_lineWidth/2.0 startAngle:-M_PI_2 endAngle:-M_PI_2+M_PI*2 clockwise:YES];    _trackLayer.path = path.CGPath;    [self.layer addSublayer:_trackLayer];    _gradientLayer = [CALayer layer];    _gradientLayer.frame = self.bounds;    _gradientLayer1 = [CAGradientLayer layer];    _gradientLayer1.frame = CGRectMake(0.0, 0.0, w, h);    _gradientLayer1.colors = @[(__bridge id)cor1.CGColor,(__bridge id)cor2.CGColor];    _gradientLayer1.startPoint = CGPointMake(scale, 1);    _gradientLayer1.endPoint = CGPointMake(1, scale);    [_gradientLayer addSublayer:_gradientLayer1];    _gradientLayer2 = [CAGradientLayer layer];    _gradientLayer2.frame = CGRectMake(w, 0, w, h);    _gradientLayer2.colors = @[(__bridge id)cor2.CGColor,(__bridge id)cor3.CGColor];    _gradientLayer2.startPoint = CGPointMake(0, scale);    _gradientLayer2.endPoint = CGPointMake(1-scale, 1);    [_gradientLayer addSublayer:_gradientLayer2];    _gradientLayer3 = [CAGradientLayer layer];    _gradientLayer3.frame = CGRectMake(w, h, w, h);    _gradientLayer3.colors = @[(__bridge id)cor3.CGColor,(__bridge id)cor4.CGColor];    _gradientLayer3.startPoint = CGPointMake(1-scale, 0);    _gradientLayer3.endPoint = CGPointMake(0, 1-scale);    [_gradientLayer addSublayer:_gradientLayer3];    _gradientLayer4 = [CAGradientLayer layer];    _gradientLayer4.frame = CGRectMake(0, h, w, h);    _gradientLayer4.colors = @[(__bridge id)cor4.CGColor,(__bridge id)cor1.CGColor];    _gradientLayer4.startPoint = CGPointMake(1, 1-scale);    _gradientLayer4.endPoint = CGPointMake(scale, 0);    [_gradientLayer addSublayer:_gradientLayer4];    [self.layer addSublayer:_gradientLayer];    _progressLayer = [CAShapeLayer layer];    _progressLayer.frame = self.bounds;    _progressLayer.fillColor = [UIColor clearColor].CGColor;    _progressLayer.lineWidth = _lineWidth;    _progressLayer.strokeColor = [UIColor colorWithRed:170/255 green:210/255 blue:254/255 alpha:1].CGColor;    _progressLayer.path = path.CGPath;    _gradientLayer.mask = _progressLayer;}- (void)changeColor:(UIColor *)color Step:(NSInteger)step{    switch (step) {        case 0:            cor1 = color;            break;        case 1:            cor2 = color;            break;        case 2:            cor3 = color;            break;        default:            cor4 = color;            break;    }    [self changeColor];}- (void)changeColor{    _gradientLayer1.colors = @[(__bridge id)cor1.CGColor,(__bridge id)cor2.CGColor];    _gradientLayer2.colors = @[(__bridge id)cor2.CGColor,(__bridge id)cor3.CGColor];    _gradientLayer3.colors = @[(__bridge id)cor3.CGColor,(__bridge id)cor4.CGColor];    _gradientLayer4.colors = @[(__bridge id)cor4.CGColor,(__bridge id)cor1.CGColor];}- (void)addRatateAnimation{    _animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];    _animation.fromValue = [NSNumber numberWithFloat:0.0f];    _animation.toValue = [NSNumber numberWithFloat:2*M_PI];    _animation.duration = 2;    _animation.autoreverses = NO;    _animation.fillMode = kCAFillModeForwards;    _animation.repeatCount = 1000;    [self.layer addAnimation:_animation forKey:nil];}- (void)changeSpeed:(CGFloat)value{    _animation.duration = value*3;    [self.layer addAnimation:_animation forKey:nil];}@end//示例#import "ViewController.h"#import "GYCirlceView.h"@interface ViewController ()@property (nonatomic,strong)GYCirlceView *cview;@property (weak, nonatomic) IBOutlet UISlider *slider;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    self.cview = [[GYCirlceView alloc]initWithFrame:CGRectMake(10.0, 110, 355, 355) lineWidth:35];    [self.cview addRatateAnimation];    [self.view addSubview:self.cview];    self.slider.value = self.cview.currentValue;}- (IBAction)slider:(UISlider *)sender {    [self.cview changeSpeed:sender.value];}- (IBAction)b1:(UIButton *)sender {    [self.cview changeColor:sender.backgroundColor Step:0];}- (IBAction)b2:(UIButton *)sender {    [self.cview changeColor:sender.backgroundColor Step:1];}- (IBAction)b3:(UIButton *)sender {    [self.cview changeColor:sender.backgroundColor Step:2];}- (IBAction)b4:(UIButton *)sender {    [self.cview changeColor:sender.backgroundColor Step:3];}... prompt'''

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参考：http://www.jianshu.com/p/64ca14e560d9