动画，锚点，定时器

///设置动画的节奏。。。。EaseIn 就是刚进入的时候慢。。。

animation.timingFunctino  = [CAMediaTimingFunction functionWithName:KCAMediaTimingFunctionEaseInaseOut];

 

 

 if (self.link) return;    

    // 1秒内刷新60次——刷新快的时候比NSTimer好。

    CADisplayLink *link = [CADisplayLink displayLinkWithTarget:self selector:@selector(update)];

    [link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];

 

 

    self.link = link;

 

- (void)update

{

    self.centerWheel.transform = CGAffineTransformRotate(self.centerWheel.transform, M_PI / 500);

 

 

}

 

 

/**

 *  开始选号

 */

- (IBAction)startChoose {

    [selfstopRotating];

    

    CABasicAnimation *anim = [CABasicAnimationanimation];

    anim.keyPath = @"transform.rotation";

    anim.toValue = @(2 * M_PI * 3);

    anim.duration = 1.5;

    // 开头和结尾比较慢,中间快

    anim.timingFunction = [CAMediaTimingFunctionfunctionWithName:kCAMediaTimingFunctionEaseInEaseOut];

    anim.delegate = self;

    [self.centerWheel.layeraddAnimation:anim forKey:nil];

    

    self.userInteractionEnabled = NO;

}

 

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag

{

    

    

    self.userInteractionEnabled = YES;

///两秒后执行里面的方法。

    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

        [selfstartRotating];

    });

 

 

}