[CAAnimation核心动画练习二]关键帧动画，实现抖动

#import "ViewController.h"

@interface ViewController ()
{
@private
CALayer* _calyer;
}
@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
self.img1.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
self.img2.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
[self.view addSubview:self.img1];

_calyer=[CALayer layer];
_calyer.backgroundColor=[UIColor brownColor].CGColor;
_calyer.bounds=CGRectMake(0, 0, 150, 100);
_calyer.position=CGPointMake(0, 0);
_calyer.anchorPoint=CGPointZero;
_calyer.cornerRadius=20;
[self.view.layer addSublayer:_calyer];
}

//关键帧动画,加入后，旋转动画没有效果了。～
#define angle2Radian(angle)  ((angle)/180.0*M_PI)
CAKeyframeAnimation* caKeyFrame = [CAKeyframeAnimation animation];
caKeyFrame.keyPath = @"transform.rotation";
caKeyFrame.duration = 0.5;
caKeyFrame.values = @[@(-angle2Radian(4)),@(angle2Radian(4)),@(-angle2Radian(4))];
caKeyFrame.repeatCount = MAXFLOAT;
caKeyFrame.fillMode = kCAFillModeBackwards;
caKeyFrame.removedOnCompletion = NO;
[_calyer addAnimation:caKeyFrame forKey:nil];