功能

点击大转盘旋转后固定到某个自己可以确定的位置

结构

转盘，开始按钮，指针

技术

CADisplayLink不停重绘，CGAffineTransform旋转，简单数学公式

核心代码

1.使用CADisplayLink不停重绘旋转底盘

// 开始转动(一直不停的转动)- (void)startRotate{        CADisplayLink* link = [CADisplayLink displayLinkWithTarget:self selector:@selector(Rotate)];    [link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];    self.link = link;}//- (void)Rotate{    //每次旋转6°    self.rotateWheel.transform = CGAffineTransformRotate(self.rotateWheel.transform, M_PI * 2 / 12/ 60 );}

2.点击开始执行旋转动画,

if (![self.rotateWheel.layer animationForKey:@"zhuandong"]) {                CABasicAnimation* animation = [[CABasicAnimation alloc] init];                animation.keyPath = @"transform.rotation";        animation.toValue = @(2 * M_PI * 5 - M_PI*2/12*(13-self.numberIndex));        animation.duration = 5;                animation.removedOnCompletion = NO;        animation.fillMode = kCAFillModeForwards;                [self.rotateWheel.layer addAnimation:animation forKey:@"zhuandong"];                dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(animation.duration * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{                        self.rotateWheel.transform = CGAffineTransformMakeRotation(M_PI*2/12*(13-self.numberIndex));            self.link.paused = YES;                        [self.rotateWheel.layer removeAnimationForKey:@"zhuandong"];                        UIAlertView* alert = [[UIAlertView alloc] initWithTitle:@"温馨提示" message:@"恭喜你!被骗了!!!" delegate:self cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];                        [alert show];            if (_delegate && [_delegate respondsToSelector:@selector(LuckyDrawViewDidFinishWidthIndex:)]) {                [_delegate LuckyDrawViewDidFinishWidthIndex:self.numberIndex];            }            self.numberIndex = 1;                    });    }

3.其间控制转盘最后停留的位置用一个变量控制就行了

@property (nonatomic,assign)NSInteger numberIndex;

效果图

demo链接：